(Rational Aeronautics and Space Bdzinktratioo) 232 P RC Rll/!W 301 Jnclas CSCL 03B G3/89 05435

(NASA-TtI-75083j t'O5KOVO OBSF9VRTORY: 33 '?78-:?0'2 Essay 011 ITS HISPCdP p"D SCIEUT'IPIC ACTIVITY (Rational Aeronautics and Space bdzinktratioo) 232 p RC Rll/!W 301 Jnclas CSCL 03b G3/89 05435

SPACE A Unclassifled - lhilimited

19. kcwdty Closril. (of chis Aped 20. Sacwtrity Clorrif. (of this pogd 210 NO. of Pagoo 22. Unclassified Unclassified 23s

TRAISLATOR ' S PREFACE

In Way of 1974 I visited Pulkovo Observatory near Leningrad, a vieit which conjured up im.ges of a tine when the o3servatory

tl was th6 %stronomical capital of the world. A century ago positional astronomy was the princid activity of astronomers.

The foudation of modern astroncQ FZS %frg built. It was Pulkovo ObSenatOry itsGlf that set the standarjs for 8 great deal of nineteenth eentnTy astronomy: the determinatim of fundamental constants, the crmpilation of fundamental catalogs of etellsr position. the determination of proper noticns and trfgo- nometric parallax06 of 8-8, the diacovcry Ev-d measurement of double stars, the development of instrumentation and rcethoda of obsorratior, for iiicreased accuracy. To study fhe history crf hilhovo Observatory is to study the development of astronomy in all of Russia over the past century and a half; it hae been the Princioal Astronomfeal Observatcry of the country since the time of its founding. During my visit to the observotmy I mas given a tour of the arounde & a ccpy of A. 5. Dadaev's 1972 rark or, the history of the observatory. As a result of the friendly attitude with which I was received, I have since wanted to make ava;lable to readers of Ewlish the historical treatise that was gfven to me. The start of this project took over two years.

Though a 1958 version 0' Dadaev's history wa8 translated into English (coincidiw with the IAU meeting in Moscow), the second

iv edition of hi8 history is three times longer and containe m-rch more information OK the post-World War I1 activities of the astronomers at Pulkovo. Baeides, the &1@3h version of 1958 is not readily available. Because Pulkovo Obaervatory ranks today with institutions such as Yerkes, Lick, Hale and Greenwich, the histories of which am importadit to aodern astronmy, I felt that my translation prcject would be rorthwhfle, both as a service to those interested in the topic and as a thanlr. you A to the Pulkov.:, astronomers X. N. Tavastsherna and G. S. Kosin. In additior, to the translation I have added a name index

(cmtaining full rimes and dates where available), a table of the observatory's directors atid to the list of references 80me roadiy material in English.

The Library of Congress 8Chs8ne for transliterating the Russim alohabet has been used thrcugnout. This may make for some confusicrn, a3 DeTch is also krtown 2s Deutsch, Canski" as Hansky, and Oskar Andreevi& Baklund is also J8ns Oskar Backlund.

I would like t3 thank Professor S. Vasilevskis (retired L'ck Observetory astronomer) for help in clarifying a number of passages. The ultimate responaibility for the translation, of course, mine. is _- ..e;-i r. F; :.i sc i :.;:.as

Medium Altitudes Mission Branch Ames Research Center. ::A?>. Hoffett Piel4, California 29 Octcber 1977 CONTENTS

?ranslator@ 8 preface Author@s introduction 1 The foundhg of the obeematory 5 The astronomical capital of the world 20 At the turn of the century 32 The expansion of programs of investigation 45 Post-revolutionary years 63 Scientific achievements and new searches 39 A second birth 100 Traditions and novelty 116 "High mattem" and everyday work 142 Mysteries and profound speculations 179 Conclueion 212 Literature 217 Directora of the observatory 219 Riame index 220 1

At the present time Pulkovo Observatory bears the name of Ptinciual Astronomical Observatory of the Academy of Sciences 1 OF the USSR, but for a very wide circle of people ?n cur country as well as outside its borders, it is known by the first of its r-aes. Founded more than 130 years ago, Pulkovo Observatory, in the first decade of its existence, acquired a reputation ~EIGR~ scientists of the whole world as a first class scientific-invesi' tigtive establishment, and the title of astronomical cupital of the world was already attachtd to it then. The world-wide repu- tatiorr and universal recognition af the observatory came ae a result of its om distinguished works in different areas of astronomy, to astronomical observations of an exceptionally great precision, and to the carefully thought out organization of the observations and the CoRfircied perfection of methcds and means af astronomy. The cbservatory is situated to the south of Leningrad, 19

'Throughout the extent of its history Pulkovo Observatory has had several official names: Principal Astrmomical Observatcry n at Pulkovo (1839-1855), Nikolaevskaia Principal Astronomical Observatory (1855-1918), Principal Russian Astronomical Gbser- vatory (1918-1927), Principal Astronomical Observatory of the USSR at Pulkovo (1927-1945), and Principai Astrononiical Obser- vatory of the Academy of Sciences of the USSR (since 1945). 2

kilometers from the center of the city, on a hill 75 meters above sea level. A straight and level highway runs almost along the meridian from the city to the observatory, the domes

W of which are visible at a distance from Moskovskii Prospect in Lenimrad. At the foot of the hill the highway forks: one /’. branch goes to the city of (formerly TSarskoe Selo)* the other to the main entrance of the observatory 81id on to r Gatchina, Pskov, and Kiev. The fame of Pulkovo stems not only from the scientific activity of the astronomers, but also from the battles fgught by the defenders of the city of Lenin, the cradle of the prole- tariat revolution. Three times in the years of Soviet power Pulkovo was the scene of a bitter, bloody struggle against :;he enemies of the revolution and socialist state. On the third day after the achievement of the rev-lution in Petroerai, in November of 1917, a confrontation took place on the Pulkovo heights between the Red Guard forces and the troops of the Provisional Governmentr which were routed there. In Gctober cf n 1319 the vJhite Guard army of Generai IUdenich was stopped asd routed at Pulkovo. Finally, the Germano-fascist troops, advan- cine: towards Leningrad in 1941, were held back here. From the Pulkcvc heights began the all-out offensive of Soviet troc s on the Leningrad front. From Sectember of 1941 till January of 1944 the southern boundary of besieged Lzninerad was defended and held one and a half kilometers to the south of the main building of the obser- 3

vatary. Intensive artillery and mortar fire from the enemy positions and boabardment from the air brought total destruction

c to all buildings of the observatory. General damage done to the observatory was estimated at 137 million rubles (or 26 million American doll-ars, in 3944 currency). - 'Phe year 1953 was the year of the second birth of Pulkovo Observatory. It was not simply restored, but rebuilt from the pound up. Present cost estimates for this- exceed prewar ones. The scientists at Pulkovo worked on diverse problems in astronmy and related disciclines, and according to the variety of 'wdertakings by a number of people, Pulkovo Observatory presents itself as one of the mas$ important scientific-investigative astronmicsl institutes in the world. Pulkovo played a significant role in the creation and development of a number of observatories in our country and beyond the border: Simeiz, founded in 1908, Kislovodsk Mountain Station n n (1948), Blagoveshchensk Latitude Station (1958) , SHernasa n n (29591, Zelenchukskaia (19681, Ulanbztar (Mongolian People's Reoublic, 1960), Chile (near Santiago, in 1962 transferred to a new dace), and others. Pulkovo Observatory has branches at Niko- / --. laev (Ukraine) , Kislomdsk (North Caucasus) , Blagoveehchensk-on- the-Amur (Far East), and investigative bases at the three points. From 1960-1964 the number of investigative expeditionary bases organized by the observatory reached 13, and of ti:ese, two- /- - Zelenchukskaih and Novosibirsk- stand now as invcstigztive centers. The significance of Pulkovo Observatory in the aevelo?ment 4

of modern astronomy is great. The activity of PUlkovc astronomers in the D&st and present includes almost all branches of observational astroncmx, with the exception of the monitoring of eneteors, which to an equal extent can be considered an astronomical., as well as an atmosoheric, phenomencn. In the litie of workers at Pulkovo were such prominent scientists as Wilhelm von P Struve,wF. A. Bredikhin, A. A. Belopoleskiis A. A. Ivanov, and A G. A. Tikhov. Their works have long been considered classical. The history of the observatory is closely connected in purpose with the history of astronomical science, and its modern activity f;.lls in lfne with the demands of science and life.

96truve is better known by the German form 3f his name (Fried- d rich Georg Wilhelm von Struve) than by the Russian form (Vasilii /- fi IAkcvlevich Struve)e (Tre note ) 5

THl3 FOUNDING OF Th3 OBSERVATORY

The date of founding of the astronomical observatory at Pulkovo is considered to be the day of its official inauguration- 7 (19) August 1839. The opening took place in the presence of

~ members of the Academy of Sciences (the full delegation), high dignitaries, foreign officials, eminent scientists and astronomers from other observatories of Russia. The event had i great significance attarhed to it. The construction of a large, well-equipped astronomical observatory near Saint Petersburg, at that time the capital, by direct authority of the Academy of Sciences was dictated by practical necessity. Russia stood on the path of capitalistic development, which sigiified the expansion of production and a fuller utilization of resources. The use of the ccuntry's natural resources was tted to the gecgraphical studies of its vast territories, and the construction of geographical maps in the end depends on astronomical observations and a knowledge of precise stellar coordinates.

So, the practical objective of astronomy at that time was- precise stellar coordinates. But this goal was not easy. Achieving it required the development of astrowmy as a scier.ce. Astronomy, Drecise posftional astronomy, which, according to the term, by definition deals with positions of celes'.:al bodies, had trJ make a step forward, which is to say, a leap .n its devel- oument. This "leap" was mani: 3ted in the activity of the Pulkcvo 6

hservatory in the first ten years of its existence. Precisely this was typified in the exceptional merit of the founder and first director of the observatory, W.. von Struve (1793-1864), who by right was one of the greatest astronomers of the world. W. Struve was not only a talented administrator and reformer, but was also an immutable ideological inspirer of the transformations conterndated by him in observational astronomy. Permanent concerns to him were to organize not only areas of positional astronomy. These cmcerns had a non-negligible significance for the development of a!-1 areas of astronomy, aqd in general preserve their significance to the present day. Let us take a cursory look at the state of astronomy during that eooch. Of course, the Copernican paradigm was accepted by scientists everywhere. But the system of Copernicus received confirmation in view of the discovery of stellar parallax (or the measurement of the distance to stars) just in the years when the observatory at Pulkovo was built. The discovery of annual stellar parallaxes (which are very snall displacements of the stars on the sky due to the annual motion of the Earth around the Sm) was made, indegendently from each other, by a trio of astronomers: Wilhelm von Struve at Dor- pat (now Tartu in Estonia], where he graduated from the university and began his scientific activity; F. Bessel in Germany8 and T. Henderson at the Cape of Good Hope. In a number of European countries at that date, and in Russia, there already existed sufficiently equipped observatories, ivhere systematic observatiom were being carried~ ... out anc?, as it hapnened, the discovery was made. Observations fr)r the mst patst wcre of-the. Moon -and piamt~~double stars, comts (when tmy were visiblc' , "fogs," according to the modern conceot, remote star congregates, galaxies arrd gaseous nebulae. Alsng practical lines, i~ par. -. . tlcular for navigatim, star catalogs were periodica2ly made UD- lists of stars with their coordinates. Of purely theohmetical works, such as celestial mechanical investigations or cosmogoni- cal hypotheses, these were not yet dealt vith, as far as they vere not directly~tiedto observations. In any case, from the evidence ef annual parallaxes to the -..- -scovery of quasars ar?.d pulsars, astronomy once again had to +ravsl a long road. For com4eT.e and final croo-F of the Coperni- can system it took almost 300 years. What a faE tempo it has developed at, in order to rebqh tf present state ~n 135 j'ears! And in this develoFment of astroncmy an important rcle beloi~gs to Pulkovo scientists.

Stellar coordinates are fundamental astronomical data, 2nd this fundamental nature is necessari2-y pmnanent.. Cnnf rc.,:5ing a Drincipal Droblem of the new observatory- the production of hi.gh-precision catalogs- W Struve DursLled no?: on13 cractical, but also purely scientific goals. The ste?iar catalogs which were used UD to the founding of the Pulkovo 0bser;vatct-y could not nrovide a hopeful basis for the sGhsequent deve!oment cf astronomy. Having been milde familiar with h.Li gjrevious Citta:oa production efforts, W. Struve used all aspects c;f a new mettiod, calied ths "science of observation." founded the Pulkcvo school of astrcmetry. In essence. modern astrmomy, as an iaoortant brancn of astronomy. dealing with various astronomical measurements. originated toeether with Pulicovo Observatory. It is neadlzss to say that at Palkovo the "art of observation." which PuEx~vcr astrcnwters and also their xedecessors maae famou3. was successfully cmbined with 'scientific observation." Sfruve's method tied testher in itself the elaboration of thepry, the constructian of instruments, and a proFaa of observing nearby an4 distant obiects, &nd a comarehensive inwesiigaiion of instrumental and oersonsl obsemathoml errors. The theoretical basis of the method might seem at first glance paradoxical, as is described briofly by the fGlicwing: a considerable test of pre- vims observaticns, comleteiy imoring the resulcs. Ia other words, on the basis of the observations W. Strzve decided to create swh stel'ar zatalogs zhich would not depend CR data of orev;ous catalogs,ar?d the objective would be t3 btrild cn the results of his cm. cbservaticns. In astrommy twc methods of observation zre distinguished: relative, when the stellar ssi- tinrs on the sky are measured with resoect to fundamental stars xith kv;own coordinzites, associated with scme catalog, a~dabszlute,

+ten the oosit'or! of every star is determined seoarately, inde-en- ?eent?y from other Stars, in ar, agreed-upon system. But it is necessary tn defir.2 the very system of coordinates. The fixing of tnis decends on knowledee of the Earth's metion, wh'ch in astronomy characterizes itself as a so-called astrnn-mica1 constar?t. 9

An astronomer nust always remember that, while carrying out observaeions, he is not situated at a fixed point ir, space, rather, on a moving Earth, determining his "dozen motions," owing to the action of qtravity and other laws of mechanics (in time he k-ows "eleven" motions). The measurement of the coordinates of celestial bodie, consists in determing two quantities- right ascension and declination. They are analogous to the geo- mphical coordinates on the Earth's surface, longitude and latitude, and in astronomy tnere are the concepts of a "celestial pole," a "celestial equator," and a zero point on the equator- the =vernal equiaox." These three concepts give an idea of the system of coxdinates for celestial objects. But the coordinate system, tied to the observations, changes all the time, as the observer ,awes together with the Earth, It is necessary t3 find sme "fixed" system or at least one which would move transversely, always remaining parallel tc one's self. IF physics such a system is called inertial, and it is, according to the theory of relativity, equivalent to an absolutely fixed frame of refereme. In order to have the desired coordinate system it is necessary to el im?nate all mti ons of +he Earth, especially ro-iationa; Ones. This consists of the proolem of determining astronomical ccnstants. Of course, in this prcblem there also enters the determination of refraction, which Is not connected to the Zarth's motion, but to the refraction of light in the Earth's atmosphere. So, in order to achieve the objectives, it was necessary to ienore the results cP others' observations, not only to necessarily 10

foreet ai;her catalogs. but to determine astronomical canstants all over again* In this was imrolved an absolute method of determining the coordinates of celestial bodies. Struve's methd was an absolute system. All the advantages of his method were agreed upon much later, wher,, after his death, the so-called fundamental stellar catalom were beglnning to be created, about which we will have more to say. In order to increase the accuracy of the observations 19. Struve prnpcsed a method of seperstely determining both coordinates. For this DurDose he ordered from Germa~y instrunents of two types, a txnsit instrumefit (objective diameter D = 150 sa. focal length f = 260 cm) for the determination of right ascertsion, and a vertical circle (D= 150 m, f = 195 cm)- for the determinatior of declination. The instruments were manul"actured in Munich according to Struve's glan by the master Ertel, and were the largest in the world for the purmse of meridian observations. itepeatedly mder- nized. they work up to the present time, carrying out a program of absolute observations . Struve also plamed a large project of relative. or differential, stellar observations, for which he obtaineda Repsold

meridian circle (D= 150 IWI,f = 215 cm), also manufactured in Germany. ReDsold's transit instrument (D = 155 mmr f = 235 cm) was used for the determination of astronomical constants (aberratior! and nutation),it being fixed on the pr'me vertical, i.e., the Dlane perDe!?dicular to the plane of the meridian. All instruments were situated in special parts of the main 11

building of the observatory, built according to the plan of t!ie h well-known Russian architect A. P. Briullov (1798-1877). The main structure (as it appears even tcday) consisted. 0, two stme buildipgs, a rest one and an B.Bt one, and a central observational part, united by corridors to the east and rest buildings. Above the central part stood three wooden octahedral towers with conical roofs. In the middle the largest of these contained a 15-inch refractor, the nork of the Gem opticians Xers and Hd&p, successors to the famous Fraunhofer. This refractor, intended for the meesurement of double stars, wae for a long time the largest in the world. Thus, the equipment at Pulkovo Obser- vatwy was most modern for its time. 21. Struve took special care in the selection of the observers. Besides himself, the scientific staff of the observatory consisted of four astronomers: his son Otto Struve, Cm Sabler. Go Fuss and F. Peters. This staff would be able to enswe the implementation of the selected progr8~1. Azready, in 1842-1843 appeared the work of 0. Struve, F.

Peters, and W. Struve b.a the determination of the constants of precession, nutation, and aberration.* Wnereas for the deter-

'Precession and nutation are periodical motions associated with the rotation of the Earth and consisting of the change of posltion of the Earth's axis in space, or the change of position of the "celestial pole" with respect to LL "fixed".Earth. Pre- cession oberates with a period of about 26,000 yaars, nutation 12

rinatian of the first -0, ctwa~*.e?.l.rsingthe Barth's rotation. it iwpired the use of observaticns carried out earlier at Green- I rich am3 Dorpat, for the detcxmh,ttion of aberration Ym Struve

utflired his GW~observatiorm mad6 at Pulkovo duriri the years 1840-1842 with the help of the trr -it instrument, fixed on the mime vertical. As far :as uhs cw!stant of aberration is asaocia- ted with the velocity of ligh-i. in space. these obaervetions of Urn Stnrve allowed him to conclude that light from all stars travels with, the same veloc€ty..af 288,433 versts per second. with an error no greater than l;jO Vm?StS (previous determinations contained error8 greater -:hm 3000 versts per Second). 3 with a period of X8.6 years. Therefore, +'Jir determination requires a number of observations, taken over a considerable span of time. Only having begun wqrk at Pulkovo. the astronomers were not able to make tile determinations solely with their own observatlons. This was supposed 20 be done -iter. The phenomenon cf aberration ariser. -ram a sum of velocities: the velocity of the spreading out of Light, and the orbital velocity of the Earth. The const,,,it of aberratior! was able to be determinee on the basis of Ldserv:itions c.a-2ied out over a period of acproximately one and a ha?? years. 3If versts are convarted into k:. orneters, the velocity of lieht, accordiv to Struve, ir 'Jd7,700 lun/SSCm From this it is obviauq that Struve riid .m*c quite correctly estimate the ascu- rT+:y of the determir*itionof the veloci.ty of light. Of c~~rse~ Until the work at Pulkovo, the best determination of aberration belonged to Bessel (201475). In the year 1896, by suggestion of the American astronomer S. Newcqmb, ip the Capacity of an internatienal expert, it was customary to adopt the value of 20f470 for aberration, close to the determinations of Bessel and W. Struve. However, the average of its values from all determinations at Pulkovo from 1840-188C (20:493), also known to Newcomb, was almost in agreement with the modern (Kamburg. 1964) accepted value (20:496). The same can be said about the constant of nutations the customary value (9:210), which we use by international agreements of 1896 and 1964, is very close to the value obtained by F. Peters in 1842 (9:214). Such an objective characterirtic of Pulkovo results is now cleared UD in full measure. Consequently, quite objective is the recognition of Pulkovr?

~~~~~ ~~ ~ ~~ -~ -~ ~~ ~- ~ its value was dstermined much more precisely thar, before, but it still was further from the true value than Struve supposed. His deterrninatZon depended on the accuracy of determining the constant of %bermtion, but into this value to an uncertain degree enters one other constant, the so-called solar parallax, or distance to the Sun, which was known also with considerable uncertainL.y.. How- ever, nct ody a more precise determination of the velocity of light, but also the establis.hment of the fact of the constancy of this velocity, which already does not depend on the solar parallax, deserves special attention. 14

star catalogs as being the highest precision of all original cztalogs containing first-hand observational facts. Confronting a basic problem of observatories, generations of Pulkovo astro- metrists created absolute catalogs of right ascensions and declinations of stars for the epochs 1845, 1865, 1885, 1905, and also 1930 and 1955. At first the catalogs contained 374 stars down to fourth magnituae, then the number was increased to 558, and in the catalogs of 1955 the nm3er of stars contained exceeds a thousad. Already brought to light with the catalogs of 1845 and 1865, arose the possibility of creating fundamental catalogs on their basis, with the assimilation of observations from other observatories. The fact is that from the comparisort of two initial (original) absolute cataloes for different epochs it is possible to obtain "stellar prooer motions," because with the absolute method-of catalog cmstruction the motions of the Earth are eliminated

(all except the transverse motion), and the charges of stellar positions in two catalogs, cornpaed by us after the decades.sep- arating one epoch from another, give evidence for the motion of most stars, also ir?cluding the traRsverse motion of the Sun, --i.e., the motion of the Sun among the star~.~These are catalog proper

4Strictly speaking, the initial catalogs contained not only the "transverse motion" of the Sun, but, as a rule, the precessim of the Earth's axis. Therefore, to obtain "absolute proper motions" of stars it was necessary to eliminate precession, which motions and not peculiar, or "properly proper" motions, as far as the nrotion of the Sun enters into catalog proper motions in an uncertain manner. To prscisely determine the velocity of the Sun's mation relative to the stars was possible only later on, and for the 1870's the determination of "catalog proper mo- ticlns" in great quantity was a huge undertaking, more as as for all practical purposes, just such proper motions were necessary. Pulkovo observations were furthered to a considerable degree with this undertaking. Fundamental catalop of stellar positions contain, besides coorcinates, also the proper motions. Thanks to this they remain suitable for every eooch and, really, represent the very

foundation of astronomy. Such catalogs are made up, originating from the results of observations of maqy observatories. Works for the creation of fundamental systems received their develop- mer?t in America and Germany (S. Newcomb, A. Auwers, L. Boss). But with all the ms+ructions of fundamental systems, Pulkovo catalogrs, displayirg gzeat precision, were inuaiably given the greatest weight. So it was, s. Itewcomb wrote, that one observa-

was fully possible with the sufficiently large difference in the eDochs of creation of the catalogs. As was found out in the years 1925-19271 with the discovery of the rotation of the G~laxy,the motion of the Sur! together with the system of planets was not strictly transverse. This in general complicates matters, thouah practically does not enter intc? the calculation. 16

tion on the Pulkovo vertical circle was equivalent to twenty, thirty, or eve.? forty observaTlms made by average observers on a meridian circle. Neweomb himself caught the gist of it and brbught to use the words of his cornpatrio2 acd contemoorary, 8. Could, calling Pulkovc the "astrommical cayital of the world." One of the first works cf Pulkovo astrono.aers that deserves mention is the investigation published in l84e by P. Peters concerning the parallaxes of 8 bright stars, based on observations made with the vertical clrcle. Peters cozfirmed the results of Struve and Bessel ar?d proved ome and f?r all that Darallaxes of stars are exceedingly small, acd, consequently, the di-tances to them are enormous. Struve himself descriSed this wprk of Peters, "as a gertuice standard pf precision and inherent oerfection."

N. Struve's classical work, Etudes g'Astronmie Stellaire, published ir! 1847 as a separate bogk, assQm,os 2 special ?lace. It was not-directly cormected to the rest of the works at Pul- kovo and, according to its title, did not certain tc positional astronmy, but rather to the realm of stellar astronomy. From hi3 profnund analysis of available data concerr,ins the distribution of stars it is gossihle to conclude how intricately W. Struve understood the pr?hlems of astronomy and the sicnificance PT Pulkovo observations for following its development. Siruve in Darticiilar der:- strated the absorption of starlight with its Dassalre through space. This result had an imFcrtar,t curistq~~~to for the developmept of stellar astronomy, and also for a resolution of OlbezS' paradox (ca. lf?26), which concerned the realms of .- cosmology and Dhilosonhy. This paradox may be formulated as follows. With a uniform distrf-bution of an infinite number of luminous objects in the universe, the brightness of the sky must he infinitely great. soaetiirng we do not observe in reality. The sky is dark, but it should atpear blindingly bright. This means either that the - - universe is finite, or some Gther thing keeis the sky from being infinitely bright. W. Struve found the *other thing" in the form of the c-ooi~icabsorption of light. Of course, as the end of the century the paradox took on another fom, and even with -the help of cosmic absorption it was imoossible to resolve it. 3aising a number of ohilosophical problems (the relativity of mTtion, an infinite universe) Pulkovo scientists at that tjme were yztill aware of the practical value of the results of their investi-tions and they did not ignore the practical Frob- lems of astronosy which also concerned them and the regulations of the observatory. In accord with the regulations, the Pulkovo Observatory scientists assumed an active participation in geodesical and aeographical undertakings going on in Russia. Any and all important wmk of an astronomical-geodesical character was carried out under their leadership, and the director of the observatory, not without reasons in his reDorts, enumerated the works oroduced by the General Sta,ff and other departments. From 1816 to 1855, field works and observations on a vast scale were carried out under the direction of Wilhelm von Struve, 18

with the aim of mrjasurirrr the different meridians between the Danube and the Arctic Sea, with a total range of 25@ 20'. This "Russo-Scandinavian arc ," or "Struve s arc. " presented at that time a very large measurement of a degree on the terrestrial surface. It even now has a great value for the determination of the Earth's :itare; even by nodern stazaards it ought to rank 2s a great undertaking. In the years 1899-1901, soonsored jointly by the Russian and Swedish Academies of Sciences, Pul- kovo aetacnomers participated in deveo and gravimetric deter- minatians cn the Spitzbergen Islands, in a most northerly tri- a-mlation of ths Earth. To Pulkovo belonged a great role in the training of geodesists and tooornaphers in Russia. At first the lessons with the tapograqhers were conducted by the director of the observatory himself, then to the General Staff was zranted the means which provided the prescriptim of a soecial assistant director, instructors with the lessons, and the purchase of necessary instruments. In the year 1856, to the northeast cf the main observatory buildine;, was built a small military department educational observatmy. From 1863 the corcus of military to?o- waphers suspended the sendine of its officers to Pulkovo, but the practical trainhe: of eeodesists continlted rieht u;? to 1917 and even later. Beginning with the ye:tr 2898, ndval cfficers- hydroeranhers were regularly cornanbeered to Pulkcwo for the taking of Dracticals, havine finished the course at the Naval Acad- emy. For their lessohs ar. observing tower was built mxt to the General Staff's observatory, which was LsStOrSd in postwar times, and oreserved on it is the name "naval tower." Soon after the October Revolution of 1917, in connection with an unusual ran- of geodesical, topographical, and gravimetric works in the country and, first of all, with the apoearance of many soecialized institutions, the broad scientific and educational activity for gecdesy gradually be3an to diminish at Pulkovo. However, for newcomers to Pulkovo, the trainin- of Russian and foreign astronomers continues to the present time. 20

TXE ASTRONOMICAL CAPITAL OF THE WORID

In October of 1861, in view of serious illness and on tha @ounds of overwork, von Struve retired from official service. _- W. / Already in 1858 the activities of the observatory were managed by his son Otto Struve (1819-1905), who was selected by the Academy of Sciences in 1862 for the post of observatory director. In the very same year, according to a new law, Pulkovo Observa- tory was transferred from the nanaeement of the Academy of

Scit-p-- % immediate subordination to .:he Ministry of Public

F ,;.>> . .ne sgecial role of the observatory was accentuated

*h..- ,awe gf the new law, as far as it w..s made equivalent to the Academy of Sciences, which was at that time subordinated to the same ministry. Allocations for the maintenance of the observatory were considerably i.,creased, almost doabling its scientific estate. For opinions concerning scholarly matters and the decisions of questions of an important nature for the activities of the obszrvatory was established the Committee of the Principal Astronomical Observatory, under the chairmanship of the president of the Academy of Sciences.. and mads up of representatives of departments, to which the activity of the observatory had a direct relationship. The change of directors took place during Pulkovo Observa- tory's period of flourishing, during its worldwide recognition and fame. Also at that time considerable events were taking place in physics and astronomy, opening new paths for -the devel- 21

- oDment of scienct+. These events-foreed Pulkovo to improv? its methods of work, in order to keeD 719 with the times. The beginning af the 1860's ms marked by the invention of snectral analysis. The application 02 it to asrronomy, side 1 by side with the illvention -f Dhotography,. prompted the development of a - av brarlch of astronomic-1 scisnca, astrophysics (the science concerning the nature of celestial objects), for wh:c> the secmd half of the XIX century was eharacterixed by the accumulation of gbsemtional materials numerous determinations of luminosity (brightness) and color of stars. the classification of stellar spectra m&-*he'q,mch fer -42ie most rational classification, the study of spectra of cDmets and nebulae, and the measurement of the velocities of ceiestial

bodies along the line of sight (the determination 0.C radial veloci-ties) from the displacement of the lines o their sgectra.

lThe invention of photogrmhy by Daguerre (daguerrotypcs) coincided with the year of founding of Pulkovo Observatory. Daguerrotynes soon after were used to obtain the first pictures of the Sun, Moon, and briaht stars. A more important aprdica- ticn war found for astronomy ax the end of the 1850*s, b td since the 1880*0*with the invention of axtremely sensitive dry bromide-gelatin nlates2 ohotograpb.y Euperceded visual methods of obse,-vinP; for almost all areas of astronomy. 22

The solution of theoretical problems of astroohypics, which made this as orecise as classical astro::omy, was pmsible by the XX century. thapdts to the successes of theoretical ohysics, in particular the theory of radiation and atomic physics. In essence, astrcohysical itrvestigzt' Ins were conducted at ?talkova Observatory from the tine of its fourding. Of swh car be consider& the datemination of the velocity of l:&t frQm the cons*ant of aberration (see above), and U. Struve's con- cluzriqn concerning the existence of cosmic absorption of light. From observatjms of a total solar eclipse in 1851 0. Struve reached the conclusion that prominences and ths ccjrpnzt were not oot'cal oheficmena caused by tne loon as assumed eslier. rather, they were fonaatims inherent to the Sun. In several articles of the postwar ?eriod the thc Cht was -xoressed that in the 1860'3 astroohysics at Pglkovo developed siowly, and the reason for this seemed to be a ne,oative attitude of the director 2. Struve towards it. This was not so. In two nacers oublished by 0. Struve for the Academy of Sciences in February of 1866 ("Photoqaohy for use in 8sT;ronomy" and "Con- cerntntz the r?le of astr. hysics in astronomy"), it is DosLible to 5 !e that the director correctly unaerstood the oroblems of astrq-hysics of that time, and the yrnose of the Daters cm- sistec' in the justification of a new directim included in th,- sDhere of the observatory's activity. Some restraint was call-4 for by Struve with the fear that the enthusiasmfor novelty ar,o if it is possible tc say, the search for discoveries witndrew 23

astronomy from its "life purxse" of sciefitific exactness and

mathemattcal mecisinn. Later. in 1889 Struve wrote: "AS far as astrophysics is concerned. its acce?tance into the circle of the observatory's activity was a necessity of the time, because without this our nwk in practical astromy woxld sox become incomniete. Also. this (I.g., astrophysics) LK s3me cf its parts is a comletely new branch of investigztion, and it is still far from that accuracy in observing and from ccnclu- sions based on this otserving compared with precise astronony, wh?ch reFresents alnost riecrovsly mathematical motions of celest'al bqdies, but the rapid develcl?ma?,t of astro2hyslcs in the last tw~decades and its successes ir, the nenticned dLractit,n (i.s., increased accuracy) clearly show its value for astronany, asd the successes serve as a euarzmtee of further irnwcvenent repmiing accuracy."* '\ The high precision of the observ;tions ade the r'ame of Pulkovcr. The cmcern abcut its ?reservation was thz business of many of the observatory's directors of prstiue. Like his

father. 0. Struve was a tal-?r.ted adin!::istrat-r, successfully i?!rectine the ohservatrrg lonier thar? Tther directzrs- mce tha?

30 years. If astrophysics at Fulkw? exki'ited cr.-.si.terabie

DP~JCDSS it? the twenty years followin ?:is ret!rtrie::t, it was his dn:nq. Ar.y new field cf science cannot develc? withcut oxist:n? ca7,ital investmerts. Astrophysics was e33echlly

2 9 ---To the Fi'tizth Year of the Xikohcvskaia Frimtoal Astro- mzical Cbservat-ry, Saint PcterskurR, 1889 p. 5. 24

demanding in this respect. as for its development powerful telescopes amt other expensive equipment was necessary. Otto Struve himelf secured the apoortioment of the necessary funds

frm the government and purchased the required equipment, beae--. ficially bestowed upon the observatory at the end of the century. But the technical backwardness of Russia on the whole. forced to put in orders for equipment from beyond the border, did not pronote a constant material base maintenance for Pulkovo Obser- va?ory at a high level. The observatories of other countries. particularly the USA. surpassed it in equipmefit. am3 the foremost character of Pulkovo investigations was preserved basically for the calculation of an abundance of unsettled questtors and in the ingenuity of the astronomers. However. in the 1860's and 1870's at Pulkovo, as at other observatories, astrophysics did not go beyond the accumulation of observational results. In the years 1868-1869 P. Rosen, a Swedish astronomer-geodesist, formerly in practice at Pulkcvo, made estimates of stellar luminosities by meam of a Z&lr.er photometer (the observatory owned two such instruments then). He devoted sDecial attenticn to the accuracy of the results and the study of the influznce in them of pnssible errors of observation. The technical secretary of the observatory, E. E. Linde- mann,continued these worksafter 1870, uslng the same method. Besides stars of constant brightness, variable stars were included in the oromam of observation. Producing. a great numbPr of observations during the extent of more than a quarter century, tinderan thoroughly studied the errors in his estimates. which included his work in a number of investigations of paramount imbortance executed at stadard of the time. The striving towards a preservation of the *life principle- of strictness and accura:y in as%roncmywas an unquestionable virtue of 0. Struve. His noutmodednessmwas reported by others. Fervently Cedicated to scientific progress in Russia. he however did not draw the Russim htelligentsia to work. As before. vacant posts at Pulkovo were filled by Baltic Germans- pupils at Dorpat University and foreigners. But for the sake of justice it follows to say that Struve was not mistaken in the scientific capabilities of those he i~vited. For e-xample.. in 1872 he invited to Pulkovo the astrophysicist B. Hasselkrg fzom Stwkholm, who introduced photombhic methods into practical observations. At that the a Dallmeyer photohelicgraph was purchased. at once adopted for the observation of a transit of Venus across the disk of the Sun in December of 1874, in an expedition outfi”,ted at Vladivostok. Hasselberg made the observations wieh the photo- he1 ioeranh. fie manufactured the ohotopraphic plates by had. requiring for it a ereat eff~rt.~The results of his phntographic observatims, although requiring a low wait. surpassed in precision the results cf other authors. who used visual methods ir.

~~ 3At that time dry plates die not exist and they used wet, colloidal dates, which were prepared before their use. 26

their observa%iom in 1876 B. Hasselberg founded an astrophysical laboratory aP Pulkovo and was engaged with spectral Lmest5wtims with the r:iliration of photogranhie plates. which he continued to wri.ufacture. He conducted experim:nts with the luminescence of gases. sWied the absorption so,wtra of chemical elesents atd cr#pourds. determined and made aore precise the wavelengths of

-spectral lines.. On the basis of the study of comet spectra carbo~cmpounda he indicated the presence of the latter Sn comets. His monograph on this question was zhe first in the world's literature. A basic principle af as*sophysical imcs- t€gatfon ams clearly reflect& For the first time in the rozks of Hasselberg- the coabination of spectral observations and EL laboratory experiment. 0-w such a principle could proviee the strictness and precislor? of results, as far as theory was lacking. In 1882 a chair of astrophysics was established at Pulkwo @$serratory, which ms occupied by Hasselberg until his return to Sweden in le89. On 1 January 1888 the loscou astronomer A. A. Eelopc,l*shi~(18sb193b) was invited for one of the vacated positions of adjunct-astronomer. In 1890 he filled the position of astrorhysics atid until the end of his life remained the Girector of astrophysical work at Pulkovo. In 1886 a sepemte astroohysical labQratory building was built with an electrical station with it, which allcued laboratory investigations to expand much io- widely. In astronomical observational technique, especially astro3hysies and as%rophatography, the lag behind foreign observatories had become apmrent- Already at the 3e@dng of the directorship of 0. Struve %ne 15-inch refractor, with which he h:mself made observations over the course of 40 years, hzd lost its place as the mcst powerful instrument in the world. Its mounting was noticeably out of date, something Struve became clearly convinced of on hi8

trip abroad. At that the the Clarks (the father and -0 sons), American lens grinders, expanded their activity, havip supervised the oroduction of large objectives at CamZridge _near Boston.

' In 1873 tin objective of diameter 26 inches was manufactured at . Clark and Sons for the refractor of the Washington (Naval) Ob- servatory, with the help of which Hall discovered the moons of

Mars in 1877. With the very saae instrument was found 8 number of close double stars, difficult for observations by mear. of the ls-inch Pulkovo refractor. All this defir,?cf the necessity of wdering a new, more Dowerful telescope for Pulkovo. Tnanks to the help of the Committee of the Observatory 3rd the Ministry of EducRtion 300,000 rubles was assigned for the ordering and manufacture of the instrument. An objective with a diamter of 30 inches (76 cm) was ordered from the firm of the Clarks; the 01mt of Feil in Paris manufactured the glass for it and the firm of Repsold in Germmi made the telescope mounting. In June of 1883 tile objective was deliv- ered to Pulkovo and the installation of the refractor in a special tower4 was completely finished in two years: the tower was built to the south of the main building of the observatnry, according 20

to the plans, and under the direction of the engineer-general C. E. Powker, one-time Minister of Communication Means. In this way Ptilkovo Observatory was for a second time the owner of the largest telescone in the world, but not for long: soon after, the Clarks manufactured__ two still larger lens objectives, with diamters of 36 and-40 inches (91 and 102 CR), for two American observatories- Lick (in 1888) and Yerkes (in 1896). The Yerkes OO-inch refractor to this date is the largest in the world. Lenses Qf larger diameter have not been made, for as the diameter 5s increEsed8 so Is the thickress, in which the light collected by tne objective is absorbed. 5

'The tower of the 3O-inch refractor. grea%ly damaged in the war of 1981-19458 was demolished in 1953. Together with the torrsr perished the telescope's mounting, only the objective hav- irqr beer, nreserved, which is situated in thz observatory's museum. %peaki% of the diameters of telescopes, it follo:.rs to distinguish refractors (lens), reflectors (mirror), and mirror-lens telescopes. Larce reflectors alre..dy existed at tho end of the XVIII century. In i789 William Herschel manufacture6 a telesccpe with a mirror diameter of 122 cm. and in 1845 W. Pzrsons (Lord Rosse) created a telescope with a metal mirror of 182 crn diameter. With the nelp of their telescopes Herschel and Rosse made many 29

In every case concerning the 30-inch refractor of Pulkovo observatory it was destined to go down in history, not only at its observatory, but in worldwide ilatronomy. The first observations with it were made by the thkd son of 0. Strave, Hermann Struve (18544920). who worked up to it from obse--ations with the 15-inch refractor. In the first two years of observatims H. Strwe carried out an investigation of the instrument and made a laree number of double star measurements. ROEhis work, conducted with tae help of the 30-inch refractor, the imresti- gations of planetary satellites of Saturn. Wars, and other planets

~ ~~ discoveries. KFwever, these gigantic telescopes were not perfect: their mirrors were made from copoer and tin alloys, without special coatings, which is why they quickly tarnished and needed repolishing. Therefore, in the nineteenth century refractors with achromatiz objectives for some time displaced reflectors. With the invention of t9in coatings (at first silver. then aluminum) it became oossible to polish mirrors of durable material- glass or Dyrex, which possessed a small coefficient of thermal exmsion. Then were created the largest reflectors: the 100-inch of Mount Wilson (1913) and the 200-inch at Palomar (1918). In the twentieth ceptury mirror-lens svstems were producelf. and also sy.3- terns with special correctional plates in front of the mirror instead of lenses (Schmidt and Maksutov systems;. produ?ed a most important result. Being also a physicist and a theoretician, H. Strwe utilized his observations for the establishment of a theory of motion cf satellites. In the motion of the seventh satcllite of Saturn. Hyperion, he discovered an extremely su%tle nhenoaaen-m- l%bration [the tilting of the satellite), which was giver! a simple exalanation with the help of the perturba- tion on Hyberion by the largest, sixth staellite in Saturn's system, Titan. This came to pass in 1888. and in 3892 he discovered the libration of the two satellites closest to Saturn- llinras and Bncel adus .* In 1895 H. Struve, having received an invitatior?_frm Kzn- icsberg to occu3y the oast of director of the observatory and orcfessor at the university, left P?rlkovo. In 1904 he became head oi the Eerlin Observatory, fok which a new building was built at Babelsberg. In that way he is cznsidered the fmnder of the.Berlin-Babelsberg Observatory. It is now apmqriate tc, speak of three more astroncmers of world renowr from the Pmni'y of Struve. The fxirth son of G.

Struver Ludwig Struve (1858-1920)r was at first not 09 the staff at Pulkovo Observatory, but later on he was a professor n at KHar'kav Unfversity an3 director of the university's cbserva- +cry. Geortr Struve (1886-1933), son of Hermann Struve, wa= aii

*A tenth satellite, ROW knsw? as JanusD was ",iscovered by A. Dollfus at Meudm Cbservatxy in 1966. It is now the closest kiom satellite tr, Saturn. (Tr. note) astrr;riomer-observer at the Berlin-Babelsberg Observatory. Par- ticularly renowned as an important astrophysicist ami administrator, the great-grandson of tne founder of Pulkovo Observatory, the son of L. Strwe, was Otto Strwe (189791963). an American astronomer, director of two observatories- Yerkes (in the state of Wisconsin), ar!d McDonald (in the state of Texas), president of the International A8trOm11kiCd Union (UU) from 1952 to 1955, and inthe latter years of his life director of the new radio astronomy obervatory at Green Bank (in the state of West Virginia). Iat us return to his grandfather 0. Struve. In 1889. after the celebration of the fiftieth year of pU.mo Observatory, the 70 year-old 0. Struve, having served at the observatory since the day of its founding, went into retirement and soon after moved to Karlsruhe. where his relations and close friends lived. He did not lose his interest in science up to the end of his fife. Concerning? his work and interests it is possible to judge accoiJ- inq to the publications of the observatory and from numerous letters preserved in the archives. 6

'In th,o Archives of the Academy of Sciences of the USSR is kept, for examde, the correspondence of 0. Struve with the well- known Italian astroncaer Go Schiaparelli, then director of Milan's Brera Observawry, and dhcoverer of the "canals" on Mars. This correspondence zofisists of 2reater than 500 items. 32

AT THB TURN OF '€+HE CEmWRY

The direction-of activity of an Institution and the condition of matters J.n it greatly depend on the director. This was clearly illustrated fn the pmrevdutionary history of Pulkavo n Observatory. When. for example, 0. A. Tikhov wrote a history of the observatory at its hundredth year, he subdivided the periods of its activity into: the new charter- a new director (0. Struve). the directorshfp of Bredgin. the activity of the observatory under Baklund, etc. One has to almost precisely follow this schere. for actually the election of a new director every time signified the beginning of a new period in the observatory's history. Of course. this did not carry with it the character of a revolution. On the whole traditions were preserved, but new--ais%inetiunsappeared. characteristic of every period. IC the sum,il: of 1890 F. A. Bredirkhin (1831-1904) became the direz SI . f -?ha observatory. elected in the same year as a reeular aca3u?;i?lan of the Petersburg Academy of Sciences. He was already t.1 important scholar, the investigations of whom 07 the theory of cometary forms acquired worldwide recognition. Over the ccurse of 17 years he was director of the Moscow Observatory and a professor at the university. With the apoointment of Bredikhin Pulkovo Observatory's "orientation to the west" was overcome. Pulkovo became a Russian center of astronomical investiaations. Bred?-Gin himself, in his first report to the Committee of 33 '

the Observatory, wrote the following: * At the very outset of the governing of the observatory it was clearly evident to me that theoretically oriented ~upllsof all Russian universities. feeline and declaring their calling to astronow, must be given, within the limits of passibility, free access to comalete practical training in this science. and then to the pursuit of all scholarly positions of the observatory.* In accord with this he at once apoointd four people as additional astrcnomers. 1 they having finished the course of mathematical sciences at the Petersburg and loscow Universities at the head of the class. Three of them ( s. KO Kostinskii. A. A. Ivanov. and V. V. Sera- fimov) clasely connected their fate with Pulkovo Observatory. The drawing of people having graduated Russian universities to the observate-y for additional positions was practiced after Bredikhin by his successor Baklund. For the calculation of the availability of "additional staff" the scientific personnel of the observatory increased itself almost one and a half times. With the aim of establishing scientific contacts, Bredikhin, in the very first year of his directorship, visited astronomical n observatwies in Moscow, KHarkov, Nikolaev, Odessa, and Kiev. Such visits he continued in following years. In 1894 he wrote: "The dealinqs wlth Russian university.observatories, so lively now that it follows to rejoice from the soul, for a more or less Drolanqed period produced Rood people for us Russian univer-

'At present this position aporoximately corresponds to the post of junior scientific worker. 34

sities constantly* those who wish to Improve one or anothe? area of astrocomy. With such a position of our business, observatories do not have to worry about a shortage of good talent, when they need it."* Finally, for the sake of the goal of the unification of

forces, in 1890 Bredi'khin orgaqixed-1 the Russian Astronomical Society and was its first chairman. J With the appointment of A. A. Belopol'skii to the post of ast-ophysicist, astrophysical observations all assumed a great specific weight in the program of observations of Pulkovd Ob- A servatory. At first BeloprJl'skii investigated the rotation of JuDiter on the basis of numerous observations of different observers. He reported --y discovered the differences of rotational period for the equatorial zone and in higher latitudes: Jupiter does not ratate as a solLC planet. Along this line Belopol'ski? began a study of the Sun's rotation according to the mation of faculae, which are chservable .in numerms photoheliomams obtained by B. Hasselocrg in-1881-1888. For the measurement of the dates he engaged the help of M. N. Morin. The result was analonous to the following8 with the degree of moving off from the solar equator to its poles, one can clc rly detect an increase of fhe rotational period. Later on, in 1905 and 1925 Belopol'skir once aEain returned to a detailed investigation of the Sun's

n 'Rep'. t to the Committee of the Nikolaevskaia Principal Astro- nomical Observatory at Pulkovo, presented by its director, Saint Petersburg, 1894, p. 4. 35

rotofion on a spectroscopic basis. & In 1891 Belopolgskif was sent abroad for the ordering of necessary instiumente- a stellar spectrograph and a photographic refractor, 3r a so-called normal astrograph. The normal astro- arrrph with two objectives, a photographic (D = 330 m, f = 350 cm) and a visual (D = 250 f = 360 cm). was established at PuXkovo in the summer of 1893. The optics of this instrument were manufactured by the brothers Henry- in Faris, and the nechan- ical parts by the Repsold firm. Atthe.3eginning the astromaph - 3 operated under the direction of Belopol'skii, and after 1895 under the direction of Kostinskii. A. A. Belopol'skii made the spectral observations by meaxs of the 30-inch refractor, transferred to his complete direction with the departure of H. Struve. In lL)s Belopol'skil began the implemen',ation of an extensive program of observatior;s of radial velocitias of s-krs, the Sun, planets and comets. It is possible to measure velocities of stars along the line of sight from the disp'icement of lines in their spectra, in compbrison with lines in the spectrum of a stationary light seurce: displacement to the red side signifies a receding source (positive velocities): displacement to the violet side, approaching sources (negatJ.ve velocities). If the celestial object is riot a star, rather, the Sun or a planet;, the slit of the spectrograph can be placed at the edge of such an object to obtain evidence concerning the velocity of its rotdtion. In the foundation of the measurement of radial velocities lies a principle for oscillatory processes in acoustics snd optics, formulated in 1842 by the Ausxian chyslcist aRd astroncmer Christian Dopder.

Acccrdiw to Dopoler, the frequency of oscillation deterted

by the observer from the source of sound or light depends OF. the relative velocity m-d the direction of motion of the observer and :he source of oscillation: with their amroach the detected frequency is increased; with recession it Is decreased. On %his basis Doppler unsuccessfully tried to explairl in par? the observed differences in cclar of t-ie com?onents (comprising) dauble stars. Independently from Dopder, the French physicist H. Fiteau dfs- covered the very same princi ile for optical chencmena in 1848. Beth arrived at this conclusion as a result of theoretical arm- matts. True, for sorant .:henme- the validity of the principle is easlly verified by exceriment. even simoly by ear. With the inclusion af smctral a.nalysls intc astronomy, the principle of iIoDrler-Fizeaii was accepted uncmdit!onelly.*

A. A. Belopol'skii proposed an experimental verification of this winc:71e apsir. in 1994, but he carried it cut in l9OO. The mea? exactness cf Pulkovc astrcnomers iF reocrted. in the very execvticm of the exoerimeiit, in relation tc the authenticity and nrec;sion of the results obtained. The iciea of Belopcl'skii's experiment was sim.lle, bu: the

+One of the nost imc.-rtant contrcversies in nodern astron-ny concerns the red shifts of quasars; which may not be due to their receding at velrci+:es ccmcarable t3 the s7eed cf liaht, zs the Don-ler orinci ]le would imcly. (Tr. note) difficulties in the hclementation were substantial, if ve bear in mind the eroraous velocity of light, the frequency ofascill2- _on (or the uavelens$h), which is to change by aeans of the reflectton of the stellar velocity, i. -e., a velocity of order 20 h/sec. In any case Belopol'skii first conducted this experi- mento Later on. B. 3. Colitsyn, a Russian physicist and seis- mologist. founder of the seismnlogical station at Pulkovo (1906), carried out a more precise determination of the experiaent. 4 Successfully having carried out the experiment= Belopol'skii continued spectroscmic observations with renewed energy. The optics of the 33-inch refractor rere meant for visual observations, and the displacemec,s of spectral lines were deternimd from photoeraphs. In order to adapt the instrument for pl-oto-

b eraohic observations Belopol'skli ordered a special cxrsction plate, the adQption of which allowed him to extend the Length of the spectrum and noticeably expand the investigated region

4 cn both sides, in the red and viclet. Belopol'skii acnieved a ereat result in relatian to accuracy of determination of radizl velncitiesr as at other observatories, for example Potsdam (Cer- many) a?:d Ik-vard (USA), already having made a considerable test of the observations, he determined velocities with errors of -+ 2.6 km/sec, which armunts to approximately 10% of the observed stellar velocities. In this way he did much in the way of the elaboration of methods of determination of radial velocities and was one of the piw?eers in this field.

4 Belopol'skii selected about 200 stars from 23 to 4th magci- tude for an investication of the Sun's motion ir! space with a statistical method? According to the measure of increase of stars observed by him, he placedamong them uany spectroscooic double stars. h?wiw numbered then in small quantity. but the inwrtant role of which was already fully realized. Like visual binaries. spectroscopic binary stars furnish inforration concerning the masses of their components (making up the stars). rotating cne relative to the Other according to the aca5on of mutual - mavity. The apqlicatlon of the law of gravity to the study of the orbits of these bodies allows the determination of their masses. But spectroscopic binary stars display themselves independent of distance. which is why, only tha?ks to their existe:-ce. 4 do the masses of more distant stars become known.

31t is possible t3 compute, in a rough apmoxhation. that stars move in different directions with velocities apprcximately the same in mapitude. If, on that assumption a systematical deviation tward some direction with a determined magnitude is obselSved in the measured (radial or catalog prqer) velxities of stars, this signifies the moticn of the solar system not only in the opposite direction, but with tha same magnitute of vel.xity. 41f a double star (implying a pair of stars, physically con- 3ected to thema?lves thanks to mutual attraction) is seperated into components with the help of a telescope, then it would be callad a visual binary, even in an instance wher. the most powerful telescnpes ad, t nhotography for the seperation. Just visual binaries were the tonis of study of Pulkovo astronomers until 39

%$inning in 1892 Belmol'akii failed to see a sirqle cut- burst of novae. the spectra cf uhfch he studied during the extent of the period of rinhum luminosity, while the obserrations were accessible to the instruuent. Especially of interest uas the dbcavery of periodtcal changes of radial &locity in variable stars of a special family. the so-called Cepheids. At the beer,- niy Belopaleskii hiuself included thea amcng dcwble stars, but the loscow professor N- A. Umv, formerly cne of the opconents of Belopclesbii for the defense of nis doctoral dissertation in 1896, expressed an idea cmcerntng the pulsatim of Cei-lheids. This idea leter on was c.woletely coeimed by both theories of ohenmena and su%equent obse-ations. In 1912 Belopcleskii susnected a cwof the intensity of the spectral lhes in Cenheids. arcd in 19&3 his student I. N-Lehran confirmed this variation which cmfirmed the idea of yalsation. After twenty-five years of observations with the 30-inch 3 refrzctor, A. A. BelopolOskii had a5tained a thousand spectro- mams of stars. the Sun ad other bodies of the solar system- He 4evoted much attention to the study of the rotaticn of ela~ets, the ahysics of c-mets and their tails. On the basis of a?: inves- timtim of the rotation of the rinzs of Saturn he established the an-earance of astrophysical methods. Astrophysics cle?:=rly defined the ccrncent of photometric binar-ces and spectroscooic binary stars. Those and many others still cannot be sephrated with telescopes. in 1895 the meteoric character of their structure, which 3-s across in accord with the mathematical thecry of the stzbility A of the rlnms, elaborated by S. V. Kovalevckais. J The works of '3elopol'skii achieved whit recognition. In 1903 the Stemburg Academy of Sciences elected him an extra- ordlnuy. and in 1906 an ordinary academicim. In 1903 - Italian Society of Spectroscodsts chose him as a menber. and in 1910 the Rcyal Astro.r.r?nical Society (in London) chose him as a nember-ccrrespondentr in 1908 the Parrs Academy of Sciences awarded h€lp the gold medal of Jan~sen.~The Russian Astronomical Society awarded him many hcnors. In 1908 the Acadercy of Sciences elected Belopol'skii to the post vice dLrector - of of Pulkovo Obsemtary. But the events just described took place far from P the limits of the 'epoch of 6redi:khin." ._ n In a number of astronomical endeavors of F. A. 3mdikh2n the ameement between Pulkovo Astronomical Cbservstory and the kgnetic Observatory at Pavlovsk, concerning the simultanecus 35servations cf mqmetic storms and special phenomena on the Sun's disk, deserves mention. The performayces of such obser- v;t€?ns were conducted in 1892; they confrcnted difficulties of

55. Janssen (1824-1903) was a Frafich astronomer ar.d me nf the founders of soectroscopic amlysis. In 1868 (a nmth earlier than N. Lockyer) he devised a spectral method of obserVat:on of solar nrmlnences outside of eclipse, and il.- 1870 developed the method c?f quantitative soectral aFalysis. 41

an adaMstrative nature, which remetfully they did not attenpt to overceme. In the observations there are definite im-licati-ns for the existence of a corwihtion of magnetic storms and the Aurora Borealis with the passage of a group of spots across the central meridian of the Sun. It is possible they night have achieved the establishment of a ournaseful "solar service'" the orcdn of which at Pulkovo was asscciated with the systematic observations of the Sun by means of a photohe14-waphrwhich 3 was made by Hasselberg and Be1opol';kii from 1881 to 1995. The

solar service WES fFnally fcmulated at Pulkovo in 1932. Other observations of an unorthcdox nature point towar5s the notion of a latitude SSrvice, which alumst from the start was maintained at Pulkovo. In 1888 F. Kustner in Gem# established the fact of the change of latitude of several Eurclpean observatories, which could only be understood having allowed motion of the Earth's polss. The verification of this assump tlon by meam of the organization af latitu& observations in Burnne and at the Hawaiian Islain 1891-1892 emfirmed it. Besides that we remenbee that the Pulkovo sstrononers F. Peters ami M. 0. N y ren both chsely apmoached the discovery of latitude chaness frem materials of their om observations. Acknow- ledecine that the matter was ccnchded with the chance of latitude of Pulkovo, they unsuccessfully atterrcted to cnrrobor;te the 305 day period of oscillaticn of the pole nredicted by L. Euier (ca. 1765). Such a period in general *as r.ot found. The American astronomer S. Char-dler showee in 1891, on the 42

basis of an analysis of a large quantity of observations (about 30,000), that in the displacement of the Earth's pdes there exist two neriods- a yearly and a 14 mcnth, or 428 day period, which received the pame Chandler perid. S. Newcomb explained the discreoarkey from the Buler period by the fact thht in his theory Euler started from a representation of the Earth as an absolutely solid body. In fact the ohenomencn depends on a nm-solid Earth core, the presence of the oceans on the surface and the atmasphere araund the Earth, and even on the seassnal shifts of air masses, scow covers, etc., that pmduce the cycli- cal chanms of the o1afiet.s mcment of inertia and the position of the axis of ratation jnside its body. In this ray the oscillations of the axis of rctaticn of the Earth are manffzsted in the oscillatcry motims of the Earth's boles, which 'trace" irraelar SDh%l-look!ng curves in the boundaries of a square with a side of 22 meters (or OV), influenchg their disolacernents over the whqle coordinate grid and especially fw Peomaohical latitude, Seine measured from the equator (or at the odes, which is equivalent because the equator can be deternined as the creometric locus of ooints equfiistant from the ooles). Nevertheless, all this w=s understood after a great number, and a cantinued span of observatisns, and also as a rasult of serious theore+ical investigations. " In 1891, after the discovery of Kcstner, S. K. Kostfnskii began lzit;+urie observations at Pulkovo by means of the transit instrurnezt on the or;ne vertical. Other oSservers continued 43

thse observations till 1911, wrio6ically publishing the results. Also in 1891, T. E. KortaZz; at Nikolaao mdde a determination of latitude by means of a portal-lz verticle circlt.. Simultaneously. a thorough rsduction of w-evious groups of Pulkovo observations on the large transit instrument and the vert;-cal circle was wder- taken am3 important theoretical imrestigatixs were carried out (A. P. Sckolov, M. 0. Nyren, and A. A. Ivanov). Analoecus observations and investigations were ccnducted by sther Eurcpean observatories. With the result of all these wcrks appeared the orwhation in 1898 of the International Latitude Semice, which from the next year established six stations (later on anly five), arranged

OF. one barallel (39* 8'), but scattered over different longitudes, in crder to be able to make an accurate mag of the motion of the pole from chzmges of latitude 9eing observed at these stations. In 1899 the Russian station of the International Latitude Ser-Fice e ,'- beean to functicn at CHardehou (in 1930 the station *as mved to Kitab, where it ooerates ever! now). The metion of the poles is irreeulir; it defies descriptim by mathematical fcrnulas, but as It is influenced by the accuracy of astrcncmical observations and cedesic determinations, the marked imnortance of uninterrupted surveys of coordinates of the pole, or latitude surveys, remains. At Pulkovo, besides regular latitude observat'ons with the trarsit instrument on the mime vertical, which were carried out from 1891 to 1911, in 1904 a zenith telescope (D = 135 mm, f = 175 ca), manufactured by the PlJlkovr, mechanic G. A. Freiberq, was 44

established for t., b>jective of a continuous littitude survey.

This instrument functicns even now, exhibiting EL standard of arecision in the skill-ful hands of several generatfons of observerrr. 45

THE EXPANSION OF PROGRAMS OF INVBSTIGATION

Declining health. .peatly disproportionate to an ardent and diligent attitude toward business,' compelled F. A. Bredthin to leave the pest of director. In April of 1895 0. A. Baklund (1846-1916), who was not ar. absolutely new person at Pulkovo, assumed control of the observatory: from 1879 to 1887 he roz-kec? as an adjunct-astronomer at the observatory. Some tim later, after his election 3s an academician in 1883., he left the observatory with the intent of devotirg himsell to theoretical pur- suits. He devoted almost his whole life to an investigation of the irre@ilarities in the motion of Bnckels CQme:, the cause of which many theoreticians t'ried to elucidate since the time of its discovery by Pons in 1818, but they have not succeeded even yet. This comet has now received the designationeomet Encke- Baklund.' Although the area of scientific interests of Baklund lay severally on the side of basic directions of activity at Pulkovo Observatory, his knowledge, energy and administrative talent promcted the successful development of the observatory' s work. The activity of Baklund at the post of director seemed a direct continuation of the activity of Bredichin. Basically, Bredikn only exhibited skill in a number of reforms at the

'At Pulkovo, before 9. A. Baklund, H. Gylden and E. Asten devoted themselves to the theoretical protlem cf Comet Encke. 46

observatory, and the realization of them fell to Baklund's lot. But the "epoch of Baltlund' has its own boundaries. First of all 0. 6. Baklund himself implemented a highly c9ntroversial arrangeBent for that the8 from 1895 he began to invite to computational work a nuuber of women having finished the Higher Besturhev women's courses in the mathematics section. Concerning the determination of them in state service. &.go, concerning being put on the staff, it was out of the question: pay for work was set up by the job. without the right to a pen- sion. Ever the special collaboration of the president of the Academy of Sciences did not allow "official rights" of the observatory's women collpagues to be gainedm2 Three of the first wcmen colleagues having maintained a bond with the observatory till the end of their lives were M. V. &lova, E. P. Milorado-

*Those having finished the Bestuzhev courses acquired the rrght of teaching in women's intermediary educational institutions. but to obtain a position was difficult. In 1895 Baklund A invited two women to work at Pulkovo (M. A. Brcnskaia and M. V. /. ZHllova), and in 1909 the number of women trained for computa- tionc and the processing of observations reached 14 (with a constant scientific staff of 18 people). Obviously, for that, in order to veil the true position of the matter, the director, in his report to the Committee of the Observatory, dispersed the mentioning of temporary women colleagues throughout the whole renort, In 1897 the works of Pulkovo wqmen collaborators began to be published in the transactions of the State Astronomical Sac iety . 4?

n vi$, and S. V. Voroshilova (Romanskaia). 0. A. Baklund obtained an increase of staff and the colleagues’ rates of pay in July of 1909, and even the essential increase of allocations for scientific and econopic needs. For this it was often necessary for him to complain in reports and other official documents of the deficiency of means which did not provide for the expansion of work: “Observatories in Germany, fiance, and especially in America have achieved such development that mr observatnry has to strain every nerve in order to occupy a proper place in line with them.“&-4 Of special merit of 0. A. Baklund it follows to discuss the organization of the branches of Pulkovo Observatory in southern states- in Nikolaev and Simeis. The geographic posi*ion of the observatory did not favor the development of many projects, therefore the question concerning the organization of a southern branch was broupht !m by Baklund at the very begi!lning of his activity

at the post of director. Thanks to his oersistence at the projected task, already in 1900 a branch came into existence at

d Odessa, where, under the leadership of A. R. Obinskii, observations wf- made by means of a transit instrument and a vertical circle with an observance of the fundamental princides of Pul- kovo actrometry. The northern position of Pulkovo allowed stars 0 to 10 south declination to be successfully observed; obserk-itions at Odessa allowe; the determination of stellar coordinates with

3ReDort to the Committee of the Observatory for 1899-1503. 48

declinations to -30'. Stars of this zone have a significance for the reliable determination of the celestial equator and the point of the vernal equinox, which establish the system of use. Besides that, observations of southern stars were important for the construction of a uniform catalog of stellar positions over the whole sky. The idea concerning the construction of such a catalog occupied Baklund in the course..of the whole period of his directorship . Observations at Odessa continued frob lgOl to 1910. They showed the possibility of preserving a precision of results with the SDread of Pulkovo methods to southern observatories. J The Odessa branch was situated on the grounds of the Novorossii- skaia University. The question concerning the purchase of its own land, formerly then vital, suddenly dissolved, thanks to a proDoss1 of the Naval Departmen to transfer the Nikolaev Naval Observatory, founded in 1821, to Pulkovo Observatory. In May of 1909 the Pulkovo astroncmer B. P. Ostaghenko-Kudrgv- r? tsev left for the management of the observatory at Nikolaev. However, the final registration of the Nikolaev branch was delayed in higher circles. Almost simultaneously with this, in 1908 Pulkovr? Observa- tory achieved the possibility of estabiishing a branch at Simeiz (Crimea) on the grounds of a small private observatory. The initiative of the buihiLng of the Sirneiz branch belonged to A. P. Canski; (1870-1908). Ye carried on negotiations with the n owper of the observatory, N. S. Mal'tsev, concerning the use 49

P of it for scientific purposes. Mal'tsev expressed the desire to transfer his otservatury to Pulkovo as a gift, together -4th the land, buildings L:,d hstruments. The notarial registration of the transfer took placs on 17 (30) November 1908, aftcr the J tragic death of Ganskii, who drowned while swimmir! in the Black Sea. The law concerning the establisbent of the branches of Pulknvr, Observatory a3 NikGlaev and Simeiz was only passed in 1912. Together with this, staffs of the brafiches (four people for Yikolaev and two for Sirneiz), the allocation for their maintenance, and the ordering of addit-ional equipment was organ- 0 ized. N. S. Mal'tsev thought to estzblish the Simeiz observa- tor;- as an astrophysical one, and it preservea that character. As before, the Nikolaev observatory remained astrometrical. Ir, 1912, in accord with this, an order from the firm of Grubb (Eng- land) for the construction of two large instruments was niader a 32-inch refractor for Nikolaev and a 40-inch reflector for Simeiz.

The volume of work at Pulkovo I;*(: increased everywhere. With an .srecedentedly fast tea;?o obselvations were made for the next (after 1885) cataiqgs :f Rbaqlute right ascensions arid 4 declinations of stars for the epoch 1905.0. The following - 4As far as the co3rdinai.t: G,ystem in which the determinatinris of stellar positlons are nnde, does not remain fixed, every catalog is characterized hv '.its OY.: epoch" - the epoch or' creation (of observations). catal-crs wore suooosed tc be for the epoch 1925.0 (actrra!!y the catalogs were created for the epoch 1939*@)0 But Baklunci, besides ti-.t, orgarhed observations with atsL-i+e methods for exterlslve intermeCiate catalogs: the catalog of 1900 contained 1213 stws from 5th to 7th map-itude and the catalog of 1915 Tmtained i631 stars of Baklund-Hoff' s list (the absolute cata- mes of 1930 contained only 558 fundamental stars). Paint stars apoearine for the first time in the catalogs allowed the pre- cisioz of observations to be irxreased, in cornparism with the brizhter fundamectal stars; besides that, they could be used for a "Link" to nlates with astrcphotoqa-hlc deterninatians. Prec! -ely in this perind astrophotomaDhic works received a wide develonment

The secod intermediate catalo;: was created as a result of an international agreement passed in 1909 in Paris at the Fifth Congress for Mapring the S~V.~For works to a compilation of %C

51, 1887 the First IEternational Cs.!gress for Astrophoto- craphy, ir! which from ?ulh.,vo @. Styuve and 9. Hasselberg Dar- ticioated, approved e decisian concerninF the compilation of a ohntogranhic ma!, of

A..he w-rlc, accmd!nk Their membership, the participation of

21 observ2tnrres cf iifferent countries was assrmed. The phctc- cpa.hic atlas, inc2ildinr;r all stars to 15th rr.agr!ftude, was supoosed tr be made up cram 22,000 lists. The work is stili unfinished. ohcto-phk -Carte -du -8CieL fundamental detenninztions of coordinates of a 1arRe number of Stan8 uniformly distributed over the er?tire skyr were required8 on the average one star far every 25 square degrees. The list of stars in the wortherr. sky (to declination -30°) was proposed by Bakclund. resultire: from the 1900 catalog with EU. acwndix of stars having been observed at the Odessa branch. This list was accepted with a few chanees. The list of stars of the southern sky was corr.:iled by S. Hoff. director of the Cape Observatary (Cape of Getd Hope). ?or tile implementation of ge=ral proerams of observations S. Haff visited Pulkovo ir, May of 1909; a month later. with the same DUrPOS?r the herican astronpmer L. doss. an important soec?alia.t in the compilation of fund=-ental stellar catalogs. came to PuLtavo. So arosz the list of Baklund-Hoff, which olayehi an imoortant role in astronomy. The csltalog r-f 1915 was nut toeether on the basis of observations at the 3ll:ovc ad Niknlaev branches .. Just as extensive 2s for absvlute observations were progracs of differentiai determinations of stellar coordinates. As already shid, W. Struve envisioned the imolemeptat. x: at Pulkcva noTonly of absolute, but also of relativer observations. However, his prwram of observatinns with the meridian circle was not carried out. After a significant curtailment of it, observat53r.s far a catalog of only 3542 stars for the epoch 1853.0 were finished iri 1869 (ouhl’shed in 1889). Five observers participated ir, its rre3ticy. A subsequent catalw of 563b stars for the exch lP35.0 was creatid with the wr:T of only s-e observer. ii. Rom5ere. who made over ?5,5w szservations in the years 1874- 1690. He made ~kzz,:-~v~--;ms(abxt 34.530 in num3er) for a catalo? of SLars for the epoch 1895.0, prqceszed mci ?re-

P d :ar& for Crir-tiyE 5y IX. H. ZeZbot (they were wbllshad in 19Cg). /r It.. 1896 the nteridiar. circle observers H. P. Dfchenko and A. S. Yasil'ev bemm the rst%eraticn of 8831 stars from the 6 cz+a?w of Schjellerup in the zoze of declirxition frm +is3tc 0 4 -1s . Their observations were pracessed by Zeibot and ware cu5,l:shed i5 the fom cf a catzlcq of b301 stars for the eToch l9OO.O. The o3servations were ccztinuee by Yo S. Xor:: and A.

A. Kxdrat'ev an2 were fkished in 1909. The prccessing of all observational ~zterialwas cnly conpleted by V. V. Serafirov in

the okv'wranhlc ---Carte du Ciel (the observat?cn of 3396 raference strrs cf the xe1s;nEfcrs zone). A substantial mdercization of the large traysit instrur.er.t art3 the nwidiar! circ' weceded the okservations frr the extessive

h s a arest sienificaxe, in carticular fsr the 3::terminrtim cf P *he c-nstznt cf wacisIcn. Tkis was ?-ne b.. IA, c. Gordo~ir. 53

promams (since 1897 tho reglsterinzs of stellar transits were prcduced by means of an 'hpersonal =kcmeter'). ar!d also a basic chanee qf nethod of observation on the vortical cLrcle (1911) ras imlemented. An Lamrtant result for the increass of precision in the determina+,ions of declinations were the works of 0. A. Baciund and I. V. Sonsdorf an a study of the phenmenot of xcZr=tticn, which was given special attention since the the of the observatory's faundirg. The reduction of observations on a vertical circle directed if. Gylden to the creation in the 1860.8 of a theory of astronasafcal refraction. on the b2sis of which A. I. Graradrskii built the Pulkovo tables of refraction, yJblished in 1873. These tables. reouhlished without chms in 1905 and 1930. achieved a ride distribution: for the fourth oublication in 1956 the tables were redone by B. A. Crlov. Thanks to the work of Bonsdorf arose the concept of local refraction. which 7 at 3nce blayed an imoortmt role. Works of an astmphysical nature dis.-l2yed themselves with such completeness, thzt they oermitted the allocations and

'The refraction of liqht with its passage through the terrestrial atmosphere makes ur, ;be principal part of astro?onical refraction. Besides that, with the differences of temperatures olitside and inside the dme, in which the instrument is situated. lizht ex3erfences an additional refract ionD called local refraction, with its entry intr, the dome. It also enters into the are- clsion of observations but does not lend itself to calculation. the set of hstrments of the observatory. Besides the worts J of A. A- Balopol'skiis the astrophysicist on the job. ad accodingto the character of his imestigatiom, it follows before all to d&l on the #irks uf A. Pa Gaashi~.who ja%ned

the obsemtory's staff only ir\ 190s at t!m post of additional adjunct-astmnoner, but actually assorriitd hUseli with the

observzkory 8-10 years earlier as P 1.0- aer'oer- In soite of tk:s relaTively short span of his scientific 3 activity. Ganskii left a deep imp-ressiun in astropkpks and by right ranks with a mater cz distinguished Russinn astronomers. He participated in three distant expet--itlons fcr the Qhd observation of total solar eclipses.nrcs a participant at the

Spitlabergen exwition, &

4 from Pulkovo. ALI.PaGanslrii oreanjted and led an zxpedition to Spain for the observatiosi of the solar eclipse of 13 (30) August 190s. He ascended in bdloons severai times and repeatedly scaied Hont Blanc for the execution of astrophysical observations. Ganskii detemiined the dependence of the appearance of the sorar corona on the quarrtity of sunspots and predicted the form of the corona in 1900. This work is often referred to evm now. He studied solar granulatior? (the "grainy texture" of the solar nhntosohere, observable when prsjected on a screen w! th g.vd images or in photoerapha r3f hi@, quality), the motions and lifetimes of existence of th.2 granules. His photographs of sa~ispotsand granulation, obtained at Pulkovo by means c.f the normal astroRraph with an enlarging camerar have lor!! rerained ulmsurpassed in qualfty. e Together with A. P. Ganskii, Go A, Tikhov (1875-1960). a well-luwm imrestigator of lars and a steadfast advocate of tne c PrJtPothesis 6f life on it, began his work at Pulkovo.’ Tikhov, already bvirg aistinguished himself ir! astrophysics, was put on the staff of Pulkovo Observatory in 1906. He received for nis supervision the so-called Bredisin astrograph. a gift of c F. A- Bredikhin. This splendid instrument (D = 170 nof = 80 em) was used in the Spanish exczdition of 1905, anti after its fl return to Pulkovo was utilized by Tikhov for photometric abser- vztions r3.th f tlters Eclipsilap variable stars we- an object of observztion which we- phowgranhed in differsnt cclors (through differeEt fC.fers). The purpose of the observztions had to do with the

search for the CQSZI~C dispersion of light, or the difference of velecity of diffusion of light in space fcr different wave- lencths. I.” such exists, then, with the observation of the beginning End end of eclipses or eclipsing binary stars, the disnlacenent for different rays must be registered then: in blue lieht the eclipse must ensue later than in the red, which comoli?s with the lesser (9hai;e) velacity of dic’fusion for blue

*In his autobiQ?x*aphical narrsti-re (G. A. Tikhov. Sixty ---Years at the TelescoRe. Kcscow, 1939) it ie possible to come across much of interest ccncerning his ow? vorks and the activities at Pulkov.:, Observatory, espectally at the 9egir.nir.e cf the twentieth century. rn light (the normal 3isr.srsim or' light). Tikhcv actuaily observed the effect suspecteo by hie. Alaost sim?iltamously with hims- the French astron-zer Nordmarn obsened the see phenomenon far eclinslrg vzriable stars. The phenomenm received the name of fi the Tikhov4crdaam effect. 3ut it was st511 not the discovery of the cosmic disqersion of lSght, which we would say concerns the presetice of the interstellar nedium: ir! 1909 9.encmer.a were n - reEtstere3 by S. I. Pueliavskii at -7imeiz, and as a result by n ether observers, which uera +Le reverse c.f the Tikhx-Iiordmam effect, which contraeicted 'rxmal disxrsion.. IR the same ysar of 1909 the renowned Russian physicist F. Pj. Lebedev attri- buted these efCects to properties of -;he stellar atncspneres e em!?loclr.s close binaries; the Soviet ustroncmer E. P. Rustel'

-* in 1934 eave h ntv intercretatlcn of the .her.omencn. nowever, A tke Ti~kb.?v-?~ox!tname.ffect ha? hardly received a final ex7lar.a- tion. 9

0Thc r,emhc-cwrespondeit of the Acailexzy of Sciences or' the US3 0. A. I.!el*r.ikov thcaght that the cosdc disoersion of light, althmgh neelieible, had tc exist, as far as interstellar selcctive akv5crrticn cf light is observed, which testifies to /r tBe crc?se*.ce cf, say, interstellar calcim. IF. G. A. Tikhcv's / a4 A. A. X?lnnrl'skiias w?k r-f that nertod the __ ;cance 57

At the time of %he peat opposition of Mars in 1909 C. A. P Tikhov photoer3phed it through filters. utilizing the 30-inch refractor. On the basis of a study of approximately 1000 A photographs of IUars Tikhov comluded that the polar caps on hrs vere saae up of frozen water (snow and ice), its fsaous 'car.als' had the =me color as 'seas', which over a loug time were said to be the places of vegetation. mis point of view is not accapted now, but is not completely repueiated. Tikhov discwered the resemblance of optical characteristics of the atnosoheres of the Earth and Mars. Although this work represents his first step in the study of Mars, it was carried out at an advanced level and has importafit consequences. Photoeraphy was aflapted to astrometry with great successr

With the installation of the normal astrograph at Pulkovo A. A. v Beloml'skii produced photograpt. of different objects by mear?s of it: star clusters, nebulae, the moons of Mars, etc. Beginning in 1895 plans for the instrument were Seing made by S. K. Kos- J t:nskii (186?-:936), one of the founders of photoeraphic ;ist,-z- Retry. In 1895 he set out on a foreign mission for a detailed familiarization with the experiment of photographic observat'ions of stars. He passed several weeks at Potsdam with J. Xeiner, a well-kncwn astrospectroscoplst, then he familiarized himself with the rnatho<*s of the Outch astronomer J. Kapteyn. A?er his

b return to Puikovo Kcatinskii 2arried on a lame program of wcrk witn a persoective several decades ahead of the times. ).ir-:tof al! an extens've seri?s of photoPranhs of Ju-iter's moons was obtained for a study of their motion. F. F. Rent carried out the processing of the observations with the additional Helsingfors plates. the precision of the photographic results surpassing the precision of visual measurements with micrometers on large refractors. For this work the Aca3emy of Sciences awarded Renz a gold sedal. The measurement of the satellites of planets led to the discoverj of an effect which was thoroughly investigated in

CI 1906 by S. KO Kostinskii on photographs of double stzrs and artificial stellar representations. The phenomenon has to do with the fact that with tu:, very close images on a photographic plate it is as if the larger one pushes away its neighboring imape, less according to size, the displacement being stronger, the closer the images are situated to each other. This phenome-

4 non received the name of the Ko.cc:nskii effect. Subsequently, the reverse effect was discovered., caving to do with the "attraction" nf im?!os - ?kc ck$rCi:k? af tks phenomenon depends

OF- many fcztoTs, in particulaz on the methQd of development. In any case, this effect necessarily -influences the measurement of an accurate seperation of very close objects on a photo- c-aohic plate. The satellites of the more distant planets (Saturn, Uranus, Nentirne) also were objects of observdtions. Neotune, with its

Y satellite Triton," was observed by Kostinskii from 1899 to 1920,

l0The second satellite of Neptune, having received the name Saturn from 1906 to 1920 (over 100 plates cf each planet). Uranue was situated at a position unfavorable for Pulkovo, arid J Iostinskii oay obtained the first successful plates of its satellites En 1519. Photography of the large planets have a significance not only for the study of the motion of their satellites, but alsc for a more precise determination of the orbital elements of the planets themselves. As far as the periods of revolution of the distant planets ard great (for Neptune the period of revolution about the Sun is 165 years), photographs of these planets, in the represenlation of points against the backgroui.ld of Stars8 gain a special importance with the increase of the spans of time of their accumulation. Therefore. the photography of the distant plznets of the snlar system- Uranus, Neptune, and Pluto, discovered in 1930- continues at PulkovD at the present time. The program of observations cf planets becaine prolonged. Prolonzed, according to plan, was also the program of determination of the Earth's own motions. To photograph the whole sky with one instrument would be an inconceivable task. This apparently, though, would be of the volume of work for the internationalCar.r;edu Ciel Needless to say, the photographing of the sky for this purpose at Pulkovo was not carried out.

~~~ ~~~ ~ ~ ~-~ ~- Nereid, was discovered by the America? astronomer G. Kuiper in 1949. Remai+-fng very faint (19!5)8 this satellite is not at all visible on Pulkovo photographs. For the Carte du.Ciel Pulkovo Observatory made fundamental determinations of the coordinates of reference stars. Kostin- 3 skii's plan was the no less grandiose and no less interesting plan; than that suggested by Kapteyn in 1906. The idea of Kapteyn's plan consisted in an objective not to study the whole immense stellar universe. rather, to organize 206 selected areas, distributed averyuhere on the sky, and for stars situated in the selected areas. to obtain as far as possible more complete data: barallaxes (distances), proper motiom, stellar magnitudes, colors. etc. In order to determine the proper motions of the stars in a selected area with the photograohic method, it is necessary to have two plates of the selected region of the sky with a difference of eprichs no less than 20 years. Of course, both plates must be obtained with the same astrcgraph with identical or very similar conditions of observations. For example, the plates must be taken on approximately the same calendar date: if a -1hotograoh is $0 be produced in a different time of the year, then annual parallax influences the stellar positions,

"Generally speaking, for the determination of proDer motions of stars plates taken with different instruments can be used, but then the reduction of the observations is significantly com- nlicated, and the accuracy of the results is diminished. Such hamens with the non-observance of Identical c.onditions 3f obs e rvat i on . -i.g., nearby stars are displaced on the alates because of the motion of the Earth In its orbit. But in the given example we are not Interested in the bnnual parallactic displacements, rather, in the proper displacements of stars on the sky in their projections onto the photographic pl9.te. mer these again are not =properly proper" (peculiar) stellar motionsr as with "catalog proper motions," here the motion of the solar system, or, the parallactic secular displacement of the stellar pasltions, does not perceptively enter. Only having been freed from it, is it possible to obtain peculiar proper motions in the projection on the celestial sphere. To take into consideration the motions of the Earth is now done as with fundamental determinations. When for determinations of stellar proper motions plates with a time span between them of 20-30 years are obtainedr but at the same time of year, then with this it is as if they eliminate the motion of the Earth about the Sun: however, precession, nutation, and other motions remain. Therefore, the measurements and processing of photo- eraDhic plates stipulates the "reduction of observations," Leg., the liberation of them from different distorting factors (the motion of the Earth, instrumental errors, atmospheric refraction,- the difference of luminosity of the stars). Kostinskii worked out the method of measurement and of processing of astronomical negatives in detail and improved the formulas of reduction. J In the accomnlishment of his prc?ram S. K. Kostihskii photo- grached selected areas of the sky and obtained "first epoch" 62

plates for the determination of proper motions of stars. He was founder of the Pulkovo "glass photo library," or "plate library," as it was mme often called, which rendered an incal- culable service to subsequent generations of astronomers. Having 4 done the "second epoch" plates, students of Kostinskii achieved the Dossibifity to determine proper motions of stars, u However, Kostinskii already was able to make a number of conclusions himself. It concerns the determination of stellar parallaxes. As is evident from previous discussions, for the determination i- che so-called trigonometric parallaxes i5 is necessary to obtain plates of a part of the sky interesting to us with a time span of half a year. Usually, for ever? section not two, but three, plates are taken: the second six months after the first, the third a year after the first. Then every paZr of successive plates will correspond to different positions of thc Earth in its orbit, from which the stellar sky, generally soeakiw, must look differently. But it looks iden-cical, because the majority of Ftars are situated very far from us, and only the closest stars will put parallactic displacement to the test with the motion of the Earth about the Sun. Precisely for nearby stsrs is there the hope to obtain parallaxes, and knowing the diameter of the Earth's orbit, it is already easy to compute the distance to a star with a known parallax. 12

12The small angle (at the Earth) in an extremely drawn-out right angled triancle, one of the sides of which represents As so '.5( with the determination of stellar proper motions, it is with the determination of parallaxes- the photographic method produces more accwate, and larger numbers af, observations in comparison with fundamental methods of meridian observations. No less a problem of determhation of stellar paral-

laxes €S one of the most difficult: even for the clasp-t stars the displacement of them on photographic plates is minute, especially a short focal length instrument. - with W S. K. Kostinskii determined the parallaxes of greater tbi 2\30 stam. True, in the majority of them the resultaRt parallaxes turned out to be within the liwits of observational error (2 OZO3). This Is explained by the insufficient focal length of the naiwl astrc?grag!it owtnp to which a long fccue photo-

the radius of the Earth's orbit, and the hypotenuse, the distance from the SUR to the star, is called the (trigonometric) stellar parallax. Even for very close stars this angle is less than

one second of arc (for the nearest star- o( Centauri- it is 02755. the accuracy of modern determinations of trigonometric parallaxes is 02010). It is not possible to measure the parallaxes of distant stars with the direct trigonometric method; with the utilization of other (indirect) methods of disiance ertimatlan the notions of spectral, dynamical, and other parallaxes are intrcluced. Often the word "parallax" is used in that case when one is slmply soezking of the distance to a celestial object,. 64

maohic refractor with an ohjective diameter of 32 imhes (81 cm) and a focal length of lo.? m was crclered. Besides that, the climatic cordit; C?S at Pulkovc? hardly favor the determination of parallsxes. Because of the white nights in the sumer and the cc.r.tir.tclus clwdy weather in the rinter, sip-ificant oerids were lost from +“-.mam af photographic oCse,Tatioris. AstrcphQtcmaohy ulayed an important role in the ra-ks of the Sineiz braxh in the first 10-15 years of its activity. Accorclim t? the h’tiative of Saklund, frm the begi:-ning of 1912 Sheiz oarticipate3 in the international prcerazi cf observatims ;?f mhcr planets, havlrg: taken on itself the +ask of systematic determination of the photographic path of csxdinates

92 129 asteroids. The southern msitio? of the branch favcred

Tho successful implementation rif this task. In ac35ition to

6 d - that, the ebse-rvers S. I. Seliavskii an5 G. h’. Neuinir. ais- rnvered aporoximately lW new asteroiis- arid seven ccmets, six qf the cxii7 discoveries eQinfr tn .iauimin. This is a lot io;: one a-trormer, and nct without ream-. was he cz1lt.i a (. cc.mot hunter .” In the neriod 9f his dSrcctcrship 0. A. Ba’rlund orgar\iz*d iwzstieraticns at the observatory in the area of celeitsd n and short perid comets was carried out (by H. V. ZHilova, E. A. /- Maksimova, t. L. Qatkevich a& lllllly others). n Having finished the narrative*f the 'epoch of Bredikhin,' it fs necessary to mention the serious beg;nnw of the time transmission service. In 1912, at ',he Paris conference on the questions of time tracsmission by meam of a radio telee-aph. 0. A. Saklund was chosen chairman of the Ir,ternational CoEnittee on Time. '?he transmission of time sicnals by radio seemed then a novelty. but soon after produced a radical change in the

deterasination of longitucle paints nr. the terrestrial surface. Until this, differences of longitude were determined with a means of cmveyance from one pcint of another chronometer, keeD;r!! ac..urate time, then for this purpose the wire telegraph was used. In 1914 a fun9amer.tal determination of the longttude d:f?erence of Pulkovo to Paris was undertaken with the help of radio. At first in Russia the transmission of acc.rate radio timo sipr.als was realized throwh the only equipped Petrxrad radio station. The beginnine of the First World War interrupted this important wcrk. Or, 16 (29) August 1916, while occupying the zost of observatcry director, 0. A. Baklund passed away. The leadership cf the cbservatcry was assumed by the vice-director A. A. 5?l?prl.lS-

4 .c skii, chcsen if-.Decer3er of the same yesr as director. In nis - 7: reonrt Bel?pd'skii sumrnarized the activity of BakluRd thuslyr "The dove1npmer:t of Dersnnnel strenrth of the cbservatcry, the imre-jse of the number nf col!eaPues, the acquisiticn nf new 66

instruments in accord with the motion of science for#rrd. the cmation of extensive themes for the activity of the observatTry. cagbined lrcientific works with foreigr. establishments. a constant unity with scholars of *&e whole world. and on the other hand. the oreanisation of an extemive investigation of the mysterious metion of Bn~ke'S cwt- all this preserves for hia the name of prenhent dfrector and significant scholar." Just woFds. a merited ap.z?raisal. WST-PmOLUTICNARY YBaRS

The social events of 1917-1921. having awakened Russia and put her on a new, totally unknown path of political and economic developent, could not paas over and did not pass over Pul- kov- S'oservatory. The point cariot be only concerning the dtu-

which shrapnel inflicted 01: the buildings, having -a.- exploded - I- over the observatory at the the -f the events of 10-12 Xovember

1913. mtDwhich carried with its revolutionary achievement of this great year, penetrated the deep inside of not orily the buildings, but more importantly- into the coRsciousr:ess of the peoole. This happened, of course, not all at once. At first the old astronomers. deservedly having enjoyed sever& privileges, feared for tkir "mcdest comfcrt." especially when "new ideas, - erroneously informed pooulation" brweht "lower serdice person- _-_- riel at ?!!e d!s~mats,-;.g %e *e -presentation of demarxls to the administriition concerning the increase of pay and "concerning the objection of quarters at the plrce having been situated beneath mound level." Complaining to local powers, who supported these demards, the director of the observatory was obliged to satisfy them. But was it not the same director. assuming the oost, who wrote about the respect of every oce of the colleagues for his ComrAes, amnns which there exist *no higher-ups or lower-dow?s"? Demccracy revealed to him in words i.: March of 1917 was spread out with his business doings in March of 1919. 68

Not ashzued of some day being quoted, the director complained: -%!he cientific activity of the observatory proceeded in the remrted ;-ear in a serious condition: the personnel were placed urrder the pke of an indeterminate position, not bcnb3 persuaded how the new geverment provides and supplies the means for the

imDleRer'ItatiOn of the task88 provided to the institution ritn prevtous epocha.*l Undoubtedly. the difftculties were imense: desperatcly needed repairs, insufficient fuel, strict rationing af elec- tsicity8 absence of transportation- all did not further the developlent of work: ad -one must be araaed that the sclen- tific activity of the observatory did not sink to a minimum: the number of manuscripts subaaitted far publication, the number of scientific transactions, the intensity of obez7-ations remai-hed almost ir. the same state as in much better times, "2 although the exhaustion of the reserves of photographic nlates, having been purchased abroad, necessarily curtailed some Zypes of observations. awing to starvation 81d exhaustion the scientific colleague B. A. ZemGov, having returned from the armed forces, and chosen in 1918 for the post of scientific secretary, died orematurely or! 2 November 1920.

lReport for the Year 1918-1919, presented to the Committee of the PrinciDal Russian Astronomical Observatory at Pulkovo by its Director. Petroqrad, 1919, pp. 3-4. 'Ibid., pa 5. €&.?.ships fell not only to the lot OF "eterrial science" rarkers. The whole country was testcd by hardships, carryiw

the burder. of art imperia1:stic war and beicfr subjected t3 for- eim intenrertion. The scholars did everything in their power t- withstmd all tests. In December of 1917, "with the prmis- sign of the director," as a directw of the observatory hinself was assumed. a? Astronomers Courtcil was created at Pulkovo. to which in June of 1918 a general meeting cf the Russian kcackziy of Sciences wanted wide-rarqing Yichts cf gcverrance CSoaser- vatories and the selecTion of all staff to vice-directsr inclu- sively. The dirxtor chose a special cormissior. consisting cf reoreseptatives frm the Astrozmers Council azd frca tne Acaeerny of Sciences, under the chalmlanship of its presisent. Ir, June of 1919 A. A. Iva~ov(1867-1939), rector a d pr9essor of the Petroerad University. astrmsmer at Pulicovo frcm 1890 to 1901, was choser. far the nost of observatory director. The Astron-mars Cauncil orxiuced new staff of The c5servat:ry with a ccnsideratZon of maximum Zratffication of its needs ?or cornmters, and with a crnsideration of an ircrease of 9erscr.nel of the NIkclaev and Simeiz branches. The staff aporcved by the

Acadeny cf ScLences ir! kueust of 1919 cansisted of 64 ozsitixs (of which 9 were fcr 3ikclaev arid 7 for Simeiz). This exceeded 'y more than a factcr of two the staff of 1912 (27 Gecple, in- clusine: the staff of the branches), the largezt wnzch the direc- tcr C. A. Baklund was able t,? achieve thrwgh the Erand patrcn- the zhairrar! of the Comrqittee of the Gbser~atcry.~Durina the period of 8aklund's directorship. in connection with the accepted volume of workr astronomers were so keenly needed for laboratory ad cemputing mrk, that since 1913 a great volume of un?rocessed photcr$raphic-.Dlates. spectrograms and catalog abscrvatians were eenerated. The new civil riqhts and recently apwoved staff allowed rnmen to be taken on as pemaiient help at the observatory. A few of the first to be out on the staff ere I. N. BalanovskaG- n bihnan, 1. V. ZHilovar and S. V. Romanskag. In February of 1918 fi S. Y. Rom-skaia became %it: first w~m-?tc! obtain access to astroncmicdl observations. In February of ?921 Y. V. ZHilova- and c S. V. Romanskaia, chosen for the post of jur,iw astronomers, joined the Astronomers Council. The active recruitme7t to the observatory of highly educated women resolved the problem af qualified cdlcillatory help. In Novem3er of 1920 the Petrograd b=anch of Pultovo calculators was orm-ized under the leadership of the experienced ami erudite astronomer N. I. Idel'son. In 1024 the staff of the observatory (toeether with the branches) reached 95 peoole, and in 1925 it was increased to 107 people, 61 of whi:h were scientific col- leaaues, and 36, technically quzlified aRd junicr technical

3From 1889 to 1915 the chairman of the Cornnittee of the Niko- laevsks.€a Principal Astrmnrnlcal Cbservatory and president of the ?etersburg TmDerial Acadmy of Sciences was Grand. Duke Ken- .--. c taritin K ons t an t i nov ich Roma,?ov. colleagdes, L.g., assistants and calculators. In such a way, as rewrds "taske gfven to the institution with previous eQocb," the stremths and means for thpir iaoiementation must have sufficed with sme left over. However, the new epoch brought new croblems. At that tine a anui.ne revqlutim in physics a& astronomy was taking place. The discovery of galaxies, the birth of relativistic cosmology. the establishment of the law of recession of galaxi2.s- all radi- cally changed the established view of the universe at the end of the last century. Jumpinp ahead, it is possible to say that many Soviet astronomers were literally "k7ocked off their feet" with the bombardment of observational facts and theoretical conclusions impetuously rushing in from abroad, where technique alloi?d astonishing discoveries to be made. But only facts - were able to oppme the facts, or at least it was necessary to vetjfy them, so as not to interpret them falsely. To obtain such a volume of facts was im.>ossible with thz lack of sufficiently powerful equipment . Highly out of date instruments were furcished to Pulkovo in volume as a legacy from previous ei)ochs, although the observatory again was considered the most wealthy among other observatories of the country in regard to equipment. The manufacture of two large, more powerful instruments, ordered from

Enelanci, was EV .Derided beginning with the World War of 1914- 1918. The resurnDtior! of negotiations with the firm of Grub3- Parsons took Dlace ir. 1920 when dLDlornatic relations with Western Europe were not far from being resumed again. These neeotiations were csrried out throuqh the Delegation of poreign Trade (Vna&tarP) in London with the direct participation of the national commissar of foreign trade Le B. Krasin. For the completion of the mrk the firm demanded the additional payment of sienificant sums (over 24.000 pounds sterling, with an initial cost of the order of l?,OOO), which, in spite of the severe economic position of the country. the Soviet eovernment allo- cated in 1922. In this way instrwsrentswere acquired for Pul- kovo Observatory. In December of 1924 A. A. Belopol's!& was commandeered to England for the inacection of the instruments on site. The 1-meter reflector was almost readyi arrangeaents for a refractor were relatively finished concerning the increase of its diameter

frm 32 to 41 inches, in order tC: have the largest refractor in the wTrld. The decision concerning? the increase of the diameter of the refractor ultimately resulted in the fact that the firm did not mantfacture the objective. A phgtoqraoh€c objective with a diameter of 32 inches was finally manufactured in Len;nerad under +he direction of D. De Maksutov, but the refractor was not assemblcd: the mounting of the instrument, cnnveyed from E5gland to Pulkmvo, perished at the time of the war of 1941-1945. The objective of splendid quality was savad. The reflector with the 1-meter mirror was transported to Simeiz in iy25 and was established in the same year. The quality 73

of theaptics turned out to be excellent. !Phe establishment of this telescope ?resented itself as a highly significant event in Soviet astronomy of the mst-revolutionary oerid. The telesccpe. however, was destroyed in 1941 during the time of the occupation of the Crimea by Hitler's troops. The excellent mirror was disfigured by a direct hit, and the mounting, removed by the occupants to Germany. was used there for scrap metal. A large Littrow system diffraction spectro$Taph of length

0 7 meters (with a dispersion of 0.76 A/mm in the third order) alcc is of cmcerr, to larae instrumental acquisitions. The saectroeraph and the coelostat to it (a flat-mirrored solar telescope) was also acquired in England and received at Pulkovo. in 1923. In 1924 investigattons of the a3psratu.s and systematic sDectrosco?ic o5servations of the Sun were begun. Tne high dis2ers;on of the anparatus allowed hialy orr\found crcblens tq be set uc and resolved. With the help of the new soectrograph d the 6@yez?-?ld A. A. Felnpnl'skii resumed his investigatlms of the law of rotation of the Sun with the purPose of the pcssible establisknent of the ccnnection betweE-, the rate of rotation and the activTty of the Sun. Acain in 1921 the Gsrman Astronmical Society' raised the

'For the internati-mal cooperation of the Carte & Ciel, the German Astronomical Sxiety (Astrcnem;sche Gesellschaft, AG), f\wnded in 1P63, played the rcle of a single international crgani- 74

questIan of repeslted obselration of all stars in the northern sky to 9th magnitude (the so-called zonal catalogs or AC Cata- lorn). The Astronomers Council of Pulkovo Observatory d Pcfded to Darticioate in this wwk. in accord with which an order was made to the firm of 2eiss for the manufacture of 8 zonal astro- qaph. The grograar of work vas discussed at a conference of sation. which compiled the work of observatories of different countries, in particular, thanks go to it for the establishment of the AG Catalcyp. undertaken in the 1870's with the participation of 20 observatories. These catalogs contained pcsitims of stars to 9th magnitude (about 140.000 for the northern sky), measured with the differential method by means of meridian circles. The publication of the AG Catalogs WAS essentially corn- pleted at the begiming of the XX century. Often these c.atalogs are called ZOEScatalogs, as with a consideration of them the sky is divided into zones of declination, which were delegated to the ohservatorios-participants of the work. The reobservation of the zor-a1 catalogs undertaken in the P92O's enoloyed a change to onotomanhic cethods for the determination of :he nnsiti.ms .-rf the majority of s+ars "attached" to reference stax, the msiticn~of which were determined with Yeridian methods (meridtan circles) . 75

the Astronomical Society called in Aukst of 1926 in Kopenhagen and it took on an international character. From PuUcovo F. F. Renz participated in the work of the conference and the zonal commission. The comzission distributed zones of observations amow observatories, the photographic determination of stellar posftions of the circumpolar zone and the observation with the meridian circle of 3300 reference stars in the zone 35-60' north declination falling to Pulkovo's lot. The zonal astrograph (D = 120 mm, f = 205 cm) with a four-element objective (for eacy elimination of aberration and an enlarged working field of 5 X 5') vas received at Pulkovo at the end of 1926. In the following year they set about to the Dlanned photography of the circumpolar zone of the sky. It especially fo17?ws t:, mention the establishment at Pul- kovc in July of 1940 of the horizontal solar telescgpe (mirror coeloctat D = 500 mmr princiDal parabolic mirror U = 500 mm, f = 1700 cm), at that time the largest instrumant in Europe for the investigation of the Sun. Manufactured by the State Optical- Mecharical Works (now LOMO),- it was the first of thzt soviet industry. The cxstruction of the telescope was supervised by the talented scien+;ft N. C. Ponomarev , the first class optics manufactured under the direction of D. D. Maksutov. The manufacture of larere telescopes in our country on the basis of the native Droduction opened new Dersoectives in the development of Soviet astronomy.

Parts of the history Gf Pulkovo Observatory during the period -- 1918-1941 involved searches for new organizational forms. Such searches were inevitable, as far as the previous organization of work, with which everything was placed under the direct supervision of the Grand Chairman of the Committee of the Observatory, did not accord with the principally new form of state government. As already mentioned, in Decemk-er of 1317 at Pulkovo arose an Astronomers Council, which independently decided many vital questions. According to the Statute of 1921, with the resolu- tions of the council the general course of scientific activity of the observatory was determined. In the charter of the Astro- nomers Council stands a presidium consisting of: the director of the observatory, his assistant, and the scientific secretary. In large measure the selection of the director depended on the council, all the remaining pcsitions being filled only through the council. The financial and economic activity was regtxlated by an economic committee consisting of the presidi.ng d.!lrzcfor. three elected representatives from the Astronomers Council and three from the remaining personnel of the observatory. chosen for the year. As is evident, the chosen basis and the democracy in the government were then established at i? high level. Because of the great rights of the Astronomers Council the director of the observatory did not play that deciding role in the activity of the observatory which belonged to him in pre- revolutionary years, although for the "scientific face of the establishment," who assvmed this position, as before, had significance. Fruitful in his activity at this post was A. A. Ivanov, for uhom A. D. Drozd was exchanged in 1931 for - short term. The directorship of the latter was an especially notable "break" from organization9 beginnings a.- His own scientific activity was organized with observations on the zenith telescope in 1917-

1920, and of the processing and discussion Lf these observations. At the beginning of 1933 the great scientific professor of /r 0 KHar'kov University, B. P. Gerasimcvich (1889-1937), headed up the observatory; Pulkovo astronomers knew him since 1915 in connection wfth his visit to Pulkovo for the earrylng out of scientific work, and in 1931 he was the head of the astrophysical

/- sector. Duriw the period of Gerasimovich's directorship the scientific activity of the observatory was strongly revived and stretighensd. From 1937 to 1943 the diractor of the observatory n was S. I. Beliavskii (1883-1953), an untiring observer and the head of the Simeiz branch for the extent of almos+ two decades. For the activity of Pulkovo Observatory, which until 1917, P ludinsz the perioC cf' Bredikhfn's directorship, remained to a simificant deqres secluded, in post-revolutionary years there existzd a charactbristically uninterrcpted growth of scientific and business contacts with other astronomical parxicipants of the country. Above all Ihe connection was manifested ill conferences of astronomers, the joint commissions and voluntary unions of scientists. Again with the life of 0. A. Baklund in the r pany of Pulkovt? astronomers a project arose concerning ar orqani- zation of Russian astronomers. The project drew the 8i;ppcrt of many scientists, and in. April of 1917 in Petrograd .",ne consti- and 19278 after this iSs activity was diseoatinued. After the chnwe there came- about in $932 a non-professienal --olun%ry union of sMcialists and amateur astronacers- the All-union

Ast-on?atical-Ocode: ical Society (VAW) which browF G in local scciety, lib the Russian Astro~=€czlSociety, c' -;n~prin-

af-the LSSR. .le Joint 'Ere Service tha c?.rirmanship of the director af

'~~1sthe first serious afiort for the cwrdinhtioh sf the wcrk,

:irlay times. 79

Traditional cataiog observatians, started at Pxlkovo at the the of the fourdhg of the observatoqi, were not discon- timmd until JuZy-ai Z941i--iheobservations and processing of the interrediate.- ..- absolute catalogs of 1915 were just flnishd, .A rhen h-1920'abservers with the large transit *tent ad vertical circle set about to create the next catalogs. out rlct azcordirg to the plan of W. Stmve, according to which the next cata7ogs were to be intentied for the epoch 1925.0. Intermediate ztbsolute catalogs of rjPht ascensions &.?MIdeclinations of 558 bright stars wece lade up for the 1930.0 epoch. And this finished in itself a .leu program of observations having come into omration. only jwt. Wing finished the previous one. The -- +- - *'- catalogs of 1925 &e-- .?--&Be the intermediate ones. In Pact they mesentad thcaselves as a cieal extension. and a rather extersive suoolement to the intermediate cat-siogs of 191s. The fact €s that the cataloes of 1915, consistire of stars of the Baklu~-hofflist, ware adopted for the special purpose of the mintenance of the basis of the photographic Carte du Ciel , ad did not fully satisfy practical, in particular geodesical, problems. This insufficiency rnig1.t have been elhinated by means 3f a rsplenishment of nrevious catalqgs o* stars to 6th magritude. "us arosd the ahsolute catalogs of right 2-scensions clnd decli- .:ations of 133c krlaht sts,-s for the eoxh 192fj.O. Arccraix te the meridiaii circle program (djfrerential 80

ob8ervations) It nekessary agar- to i'inish the processing of nurerouu obscrmtioms of a large ntldbar of *.tars of the HelsingfQ@ aWgt ad the ntalog of Schelltrup-. But in 1929 /3 Me untie- A. A. Itoa-at*ev. also U. I. ~eliLvand 14. A V. TSimer&n. set about to the obsarvatiom of reference stars of the sone 3S-6O0 foa the hternational prograr of the AG Cata- logs. 'Iche work ras carried on to the e& of 1934. However, in 1932 a new extensive proof observattons was outlined. the %mplementatio&f mich other observatories of the WSS8 took part in. -The questioa h~comern~l~the eo-called "Catalog of Geodesical Stars," contairbg accurate gositions of all stars to 6th magnitude Cr- the pole t- declhation -loo. _.-- - mis catalog contafns wstall (ria very few exceptions) stars of the absolute Pulkovo catalogs ot 1915 Lud 19258 and according to the accuracy the new geodesical catalog must have had to excel1 the resultant absolute catalogs. Por stars of the Baklund-Hoff list (the catalog of 1915) this right have sufficed by meam of a pcocessine: of all existing tsttalogs. As far as the Baklurad Hoff list vas recognized internationally, many observatories produced observations of stars on the list. The Astro- nmical Institude in Leningrad and Pulkovo Observatory made that Drocess'rx, ant2 the summary catalogs were dlished in 1934-1935. Positions of the 1334 stars of the 1915 catalcg stood to increase precision. For this all 1334 stars had +o be observed with maximum thorouphness repeatedly by scvera? Soviet observatories it?cluded in this caorerative work. N. V. TSirnnerlr,~\.(lRgQ-i?~~) d unguestiokble pro@ess in the implementation of the firs% *- - larm joint effort of soviet observatories allowed astnurorers- to setrbout to the mal-iration of a far -re grandiose pian- the establishment o,+ a catalog of precise positions of faint stars. __" I &i- -4 In 1932 B. P. Cera8bvich @ It. I. Dneprovskii suggested a deeoly &d thoroughly thought out proposal concerning the creation of such a cathog. They did not have a narrowly ?rzctical ob- fective, rather, an. extemive long range scientific proeranu "The universe of Struve and Bessea accessible to mearurenent was contained in the sphere. depicted from the center of the Sun with a radius of a few parsecst the ur,j-verse of Ehapley and Hubble tcok UD the soace of a hundred millior! parsecs. . . As an

'Pmceedines of the Astronomical Conference Pulkovo, 5-9 March 1932. Pulkovo Observatory, Leniryrad, 1933, p. 137. In 02

experimental strategy they did not propose to throw all powers "to the assault.' for the achievement of new. unprecedented boundaries. for which no one had the means (high powered telescopes). and tu cancentrate the organized human reserves to it. in order to assimilate and seewe the thirgs achieved. For soviet astronomy. only having started to play havoc with its forces. this prowam was especially reasonable: it allowed the most advantageous positions at the advanced borders of science to be taken. the cited quotation human understdings concerning the universe of the 18BO's and 1940es are compared. H. Shapley and E. Hubble were American astronomers whc made especially significant contxi- buttons in the development of extragalactic astronomy. In partic- uls~c,Shapley developed the method of determination of distances to Ceoheids. which are called the "carrdles cf the universe": he studied the structural features of galaxies and their distribution in space. Hubble was the first to demonstrate the existence of extrqalactic stellar systems, having resdved the most nearby galaxies into stars: he established the law of "red shift" (recession of galaxies). A parsec (parallax of a second) is a unit of distance equal to _9.26 1:ght years (1 pc = 3.08 X 1013 km). The latest sstronony and radioastrorz? deal with distances not in the hundred mill: ons. but in billions of parsecs, Leg., distames to IO*%,,,. The program of Gerasimovich-Dnepromkii turned orlit as persbective and solely correct as +he program of obcervations of We Strwe was in its own time. The idea of a catalog of faint stars can be elaborated in the following way. The fundamental catalogs made at the ern3 of the XIX and beginning of the XX ceritxries in essence contained in them brimt stars8 L.g., stars primarily near to us; stars contained in then were heterogeneous according to spectral ntake-un, and consequently. their positions and proper motions were affected by different accidental and systematic errors. In a s€gr,if€cantnumber of cases one can avoid this, reasonably bvi- Diciced up a suff ic iently uniform complement of (faint) stars8 faint stars beim advantageeus Rot only because the accuracy of the determinations of their coodinates is esser.- tially increased. but also because they stand as resultant bench marks for the distant and extremely distant probbj cf the universe, beiw more remote from UR in colaoarison with bright stars. In arler to obtain cowdinates of the bench marks, pctssibly nore arcurately, the coordinate system itself, connected with the 'celestial equator" and the olane of motion of the Earth about, the Sun- the ecliptic- must be "fixed" with all reliability, for which the observations of planets. and not the Sun, are to be advantapeously utilized. Finally, the bemh marks must orovide, as far as possible, "absolute values" of prq3er mo- tinns, which follew to be determined according to practically fixed objects- remote galaxies. All these points of a ccmmon 04

idea were new as an idea itself. The interlacing with them of astrometrical, celestial-mechanical, stellar astronomical, -. and astrophysical problems dethe whole problem especially imiting. Not by chance were the scier,tists ardently devoted to the proeraan with er;thclsiasa. Moscow astronomers took to the matter mrticularly actively, havirtg done the work under the direction of Y. S. Zverkv in such a manr-r as to correctly personify the ideological pro-am (the selection of stars of the program, the exdoitation of the method of observationst the arrangemefit of forces and means, the tria, clbservations and other questions). The war interrupted the business which had begun. . . Worrying about a number of scientific problems concernin@ anticipatory v.ork in science, Pulkcwo astronomers, as in previous times, aid not forset about the practi-a1 pro3lems having a national-econoaic significance. An example of such is the "Cata- 109 of eodesical Stars." However, it follows to also mention the organization of a time service on a wide -cale, L.g., not only for the use of Pulkovo abservatory itself, but for all ccuntries, expandim on a wide path of accelerated economic development, with which the Drecisior?. in time plays a paramount r-le. Accurate time :.-er

On 1 Decs- *I E: - ...~>rof preliminary ex?eri- ments, signals -1 .I be regularly trans!! i tted frm Pulkovo t .. -'. _.. ' 'e.t:r?qrad radio station "lli'ew fi Xollandia,a and on 2s Xay 1921- also t-hrough the bOoscow :KHo- dynskaia) radfo station. On 11 July 1923 *New HdPamiia' was A reolaced by the Detskosel'skafa radio station, whkh did no$ break the regularity of transmission. Althaugh the Moscow transmitting stations all were changed, the regular prsvision of all organizations and expeditions in tne country with accu- mte t€me from Pulkovo continued until 12 July tg41. The dia- continuance of transmission from Pulkovo did mt affect the vital means of accurate time to the yconsumer," as far as the fi broadcast of radio time simals wis nrcduced also from Tashkent c sincc 1929, and in 1931 the P. K. Sliternberg State Astronomical n Institute (CAI%) In Moscow organizec? th remlar transmission of rhythmical signals of accurate time. The establishment of the Interdepartmental Time Service Comr?ission in 1924 Dromoted the development of separate ser- .. vices: if in the first years of Soviet rale only two acmrate time services operated (Fulkovo Observatory and the Principal

Board of Weights and bIegsures)r then in 1938 the nu?? ! of them reached seven. In 1928 the Cormr,ission began to publist summary features of rhythmical radio time sianalsr which had an innor- tant mespint for "cr)nsmers. The Bureau International & La ?lire set ahwt to Drnduce a;LzilFgws ouhlications in 1931. The observations of lcngitude dffferences between Pulk2vo Ohservatwy and sther o-ints undertaken at Pulkovo Observatory had an imycrtant wactical zignificance. Thus. in 1925, with the help of a rzdio tele3ra3hr the loneitude difference of accurate value of the longitude of kfkoro, - rendered, as all longitudes, from the iero meridian of Green- rich. was especially important for geodesical aai-geomaphlcal investigations. -,In 1928 the Russian Ge&hfca3 -6ociety ammhl a gold &al to the executors -of wis work. Then f3llEoued a series oe-determfnationa of differences8 Pulkovo-NikoEaev 41928), Pulkovo-Hosccw (1930). and with the partkipation of Pulkovo astroaomers or even with the unilateral - meth-od were- determined the longitudes of Siaeia (1928), Sverd- 0 lovsk and Tbilisi (1930), Arkhangelsk (1932). Novosibirsk (1936), and other doints. Pulkovo Observatory assumed participation in the determination of the longitudes of several points on the -- course of the-Baltic Geodesical Cowsslon (the USSR joined this counission in 1929). and organized a wble series of geodesical - and pavimetric investigations "on the riq": HelsSnki-Stockholm- Cownharren-Potadam-Riqa-Tallin-Pulkovo-Helsi?ki.

*With 8uch Geterminations astronnmical observations were orcduced at both ooints with observers changing their places. The carrelation of resulte of treir observations (from which the difference of lonaitude was calculated) was attained as far as possible simultsnewsly thanks to the receotion of accurate radio tihe simals by both observers from some prechosen radio station. - -- -

~xom'Se&enher.1915 4to Decem-. 1928 the .Iatitdea. service OP PttBoyo- bbsermtory (8ystedfe-&emations on tie renith d telescope) produced observations ~ for 'ai-extemive program

'might leng,* L.g., frosr spmet till emrise. The F-V. pr& c-overett a5- eignificantiy greater quantity of stars.. than .before. The' ppsptgte ofIsuch a program consisted of .the fact that,- bhhs study gene&' character the pole's t& of -the of -. --+ . 5 - -'* 1 - motion. ft -- to reved.,sh*rt perih in particular a daily variation of latitude. During the l3-year per%&of - the extensive progi-am of observations over 2?,_000 latitude measurements, *and durim the period 1904-191 about 58,G'OO determinations, were obtained. !Che analysis of this colossal material showed that Pulkovo determinations possessed a very high precision and allowed to serve even the control of the Intercational Latitude Service. Observations for the extensive iwcgram revealed in the oscillations of latitude the exist(?nce of a daily term with a very small amplitude (0004), thz r.ature of which even now is not understclod. Latitude obse-xvations wei-e even revived on the transit inatruinent on the prime verticai. Prom 1913 to 194? A. S. Vasil'ev -(1858-1947) prquced observations. His results, pub- llshed In 1952, summed up the centennial observations of the transit instrument on the prime vertical, started by the POUP- der of the observatory himself, W. Struve. The fmdamentel inference of A. S. Vasil'ev consisted of thc fact that the dai ly oscillation of latitude discovered by him (wi ch another 08

phnse and with an amplitude of Ot16, essentially greater than on the Senithatele8cope)resulted from abnormal refraction, - with wdch,- however, other authors did not corroborate. The magnitude of the daily oscillation obtained by means of the sexkith telescope 58 taken as more reliable, but_. the overesti- mated value, determined from observatiori on the transit instrument, possib'y characterired 4 -3;. of the instrment, for examble, its greater susceptibility to changes of temperature of the surrounding air. Let us return to astrophotography and astrop3ysics. After the lapse -of two decades photograohLc plates from the "plate J library" of S. K. Kostinskii began to acquire a special signi- * ficancE The repeated photography of Kapteyn's selected areas" was undertaken 21-1924 and 1932. On the basis of this was carried out the determiqations of stellar I-oper motions with a difference between epochs of photoEraphy of 12 and 20 years. The trial work (with a difference of epochc of 12 years) was a catalog of proper motions of 3189 =tars in 13 areas, published L. n by A. N. Dejch and E. IA. Perepelkin in 1935. Then in 1940 b a fundamental work oY A. Nc Deich concerning a catalog of Droner motions of 18,000 stars in 74 selected areas was brought to light. The precision of the catalog stood at the level of modern demands, in spite of the fact that the narmal astrograph was the smallest instrument of those which were used for the determinations of prcper motions according to Kapteyn's plan. Another ?.wee astrochotographical work was imolemented in comectian with an international commitment- tS6 participation in the reobservation.of the AG Catalcgs. The photography of the circumpolar repion of the sky by &ems of a sonal astra- + ._ U maph was undertaken by 1. A. Balanovskiir under his direction the processing all plates (about 200).- tlne&E+easure&ent, and the calculation of "plate coii~tants"was carried out. Later qn (for the calculation of stellar coordinates and sumky .J fi d results) the leadership was passed on to S. I. Peliavskii. The reault of the work was the "Astrographic Catalog of 13,322 Stars between 70' North Declination and the North Pole," pub- 1;shed in 1947. Kante;-,i's ctlan found reflection in the astrophysical inves- A tigations of Pulkovo dbservatory. In 1926 S. A. Tikhov under- took the determination of colors or' stars in 91 Kapteyn areas with the method of the "longitudinal spectrograph." The ePsence of the method, suggested by op3 writer in 1916, consists in the utilization of a defect of the Bredikhin astrograph- uncorrected chromatic aho-ration. As far as rays of different colors do not collect at the focus identically (not at one point), .the Dhotoerrabhy of stellar images will look circular on the pla'-e, affected differently for stars of different colors, eepecially if the middle of the objective is masked from the incident beam with dn opaq?le disk. Carryire out the calibrdtion of stellar imaees for stars with known colors, it is then possible to determine the colors of other stars in great quantity, which was dme. The results of the determinations were nublished in the form 02.- . catalogs &m 193Cp-d 1951. *n The interests of *G. A. 2ikhov brought him also to investigations in t?re area ef amspheric optics atxl obervatiorar, of solar eclipses. In the summer of I927 an expedition sf

Pulbovo astronomers with I. A. Balanovskir at ~ the head depart& . for Malmberget (Sweden) for the observation of the total solar a-i_ _-- CI- eclipse af 29 June 1927; amng them 0. A. TEhhov assmed -punti- cipation. who obtained photog-a

the observations were associated wlth many expeditions. At n the beginning of the Patriotic War C. A. Tikhov placed hircself at the head of an exwdition to Alma-Atc for the observation of the total eclipse of 21 September 1941. After the war P Tikhov rerr.ainsd at Alma-Ata where he organized the Sector of 0 .>stro-Bttany for the Academy of Sciences of the Kazakh SSR, and he entirely devoted himse2 to iwestigations of Mars. In observations of the Sun at Pl.dkovo itself, except the 3 *nrir of A. A. BelopoJ!8kfir new irections of investig-.tions were n outlined. In 1928 E. IA. Pereoelkinbegan, and in 1933 jointly r\ h continued with v. I?. Viazanitsyn, s:Istema-,ic cbservations of alar orominences by means of the 30-infL reIrac,tw (with the snectral method). In 1932 analogous obcsrvatior'r of the chr~ma- s3hcre with the utilization f the Littrob 3pectrcgraph were IJ c~rieQon. If A. A. Belopalskii measuceu the positions and disolacements of lines in the solar spectrum, on the basis of n which he Based the law of rotat1cAaof tk? Sun, then E. XA. Pere- nelkin brovided the fundamental method for the photometry of sbectral lints, Lon., the qualitative measurements withik: lines (the widths of the lines, their Drofjles and the strenehs of ahsorotion in them), which allowed the physical conditicns in diffetent layers of the Sun (phJtosnhere, chromosphere, and oroai2ences) to be more widely presented: the relative maintenance of different chemical elements in these layers, the velocities of different ~xmsproducing the spectral lines, the electror! density and electron Fressuro, etc. I:i relation to the law of ro.bation. of the Sun, J-oung scientists drew concl2- sions not only concerning the character of this law accordirg to heliozranhic 1cr.iqitude (like Belopol * skl i 1, but also de Ten- dinE on the deoth of the laycrs of the solar atmosphere (frorc snectral lines of different chemical elmer.ts, not hxving an idantinal distributioq with deqth) .3 They determjned ,he exis-

jWith 2pth (as far as the word is lrsed concerning ite in the ora;, .L. . and in the chlt P asphere, of large turbulent

(mixing) velcciti? 3 of attn.;, which exceed their thermal velocities- the thema‘ velocities of atoms are che-acteristic of the dver\ tem?errchurem--

LZ One of the most ia:ortant results of spectrophotometric

investigations cf brominences VIES the establishment of that fact, that the relationshi? of the intensity of the lines of hydrorzer. and calcium revealed significant fluctuations from oramhence to promirxce, and, on the average, for a large cumber of :-rominences this relation smaothe! v charged with the solar activity cycle. The htensity of spectral lines depends on the nuc3er of atoms participating in the formation of lines, and also rm the quantity and quality of radiation passing through the cloud of atoms (~s).As the relative quar.tity of atoms (calcium and hydroeen) cannot be essentially different in seoarate mominences, an3 what is more, it does mt change

-elati\rcly small change) not so much the chemical comzosition chawes is the temperature conditions determining the degree of excitation of the atoms (the ability of them to emit or absorb radiation). The conditions of excitation strongly differ for atoms of different elements, and therefore, sometimes even wjth ths relatively small change of temneratura, lines of one element vanish in the spectrum of the mixture of ,cases and lines of other elements acpear. This precisely is cnaracteris- tic for the different layers of the Sun. 93

in the whole solar atnosnhere, and its the quantity of solar radiation is also considered to be invariable (the "imrariabil- ity* of it characterizes a SO called sol3r ~orwtarit),~then debending on the phase of the sun'^ activity the quality of radiation chanTest with masximum activ!-ty (greatest quantity of soots) the rale of the Sun's ultraviolet radiation increases. In that way was established the "ultraviolet index" of sclar activity (ordinary indices of activity arz pooled toether from the observed number of sanswts an& the n;uaber of groups of smts, and alsn of the general magnituCe of their araas)i cl In 1932 E. IA. Perepelkin organized a continually Tunc- tioriw solar service. This service was already conceived twice at Pulkovo- In essence, the photoeraohy of the Sun by \r Hasselberg and Belopol'skii in 1881-1895 already embodied the F service itself. In 1921-1929 M. V. ZHilova produced systematic

'The solar constant is the total quantity of radiatrm emanatirgr from the Sun in 1 nin to an area of 1 sqare cm which is located at the limits of the terroetrial atmosJhere, perow;- d;c?ilar to the solar raw%,at the aviraga distance of the Earth

*9 the Sun: it amounts to about 2 cal/cnE nin. The !j percent limits of uncertainty stinulate the difficulty of a comolete estimate of infrared and ultraviolet raeiation of the Sun. TiiE rttempt to establish the posa'ble fluctuatirns of the solar constant denendine on the Sun's zctivity was not brought to the determined results because of that difficulty of measurement. 94

ahservatiow of sunsmts and faculae by ream of a 3-inch Zetas ?c,?pe with pr??jectfmof the solar hag@on a screen. 5

Houever, only a? acute need fn :??a given service allowed "to set it on its -feet* finally. This need amse first of all as a result of quickly developing needs 3f ccmunication (telemanh ar.4 esoecialty radio), the continuity and clearness sf the work of which deaents on the condition of the icnes?here (the electr??ally chared layer of the Szch's atnosphere) and the mametic field cr' -:he Earth. and the cmditim of ?tie latter -. in its own right is dete;c,n,-a z!th solar actrvity. The pra-tical sic>ificance of the s:lar service ha2 not r%s failed ts 5e demonstrated. Data of thib service were not only utilized witn tha establishmenr of cammunication, as far as the a-tivity of the Sun affected may enphysical ohenmena, but also in various

statistical investimtions I! even in aedicinal practice. as was estab?ished the ccnmctior, 3etween the activity cf the Sun md the condition or' health of peode sufferine frcm varicus chrcnic d;se.zses. In connectlor! wit): this peat value, the forzcast cf s-lar activity was achieved, and the forecastin?, more cfter! nf all

c I In vari ... Lit r?;-wrts of the Principal Astrenmical Cbservat:ry dur;w these years tables of the cumber of suns;sts (and fcculae) and tho quantity of croups of saots per mczth were set fcrth. This is 3rJcise'ly that which follows for the wcrkine cut of relative "Wolf rc.imbes," which are wl..=ely used as the mst ohvi?us

in"ux cf snlar activity up till POW. 95

more reliable in coaparit.:on with Durely theoretical methods, again insufficiently exploited, was produced on the basis of statistical generalizations of results of previous observations. Th&t is why the publication of _the 'Catalogscf Solar Activity.^ started by Pulkavo Observatory in 1939 (the first eatalog con- tahed data for 1932-1937). has an important me&?:ng. With the - organization of the Pulkovo solar service (observations of the Sun with the photoheliograph produced at Simeie) in essence arose the "United Solar Service" in the USSh da%aof other 4.- o5senratories (Teskent, KKm'kov, Abastuman;) were received at Pulkovo and incluCed in general Begiriziir-i in 1938 the reduction of Lata to a single system was produced by R. S. P Gnevyshev. under whose direction the publication of the cata- laas cor,tirtued. Highly-. valuable were investiedtions of the I ..~ influence of solar activity on the character of Yarioiis terrestrial Drocesses conducted by Pulkovo astronomers and collected in soeciai monogranhs. 7

Repeatedly in the 1930's came up the question of the orsani-

6At the present time summary data of catalogs of solar activity are usually built on the basis of results of observations of 10 soviet solar services and 5 observatories of social- ict countries. .* P fl 'M. S. Eigenson, M. N. Gmvyshev, A. I. Gl** B. M.Rubashev. -Solar activity --and its terrestrial manifestation. goscow, 1948 . 96

aation in southern lands of an astrophysical branch of Pulkovo Observatory- a well-equipped base constructed in more favorable climatic arid astrr, zlimatic ccnditions. Huch of the attention was devoted to the selection of a suitable site, for which in

A c\ 1935-1940 were equipoed expeditions to the CrisPea, Kakhetiia, and Central Asia8 theoretical questions of the study of the astro-reeinme and astro-climatic conclitions wsre pursued Side by side with this remained special themes of a practical nature concerning the investi5ation with astrophysical methods of the terrestrial atmosphere, the luminescence of the night sky8 and P the polar aurora (C. A. Tikhov, D. I. Eropkin. 24. A. Kozyrev). With the establishment of the 1-meter reflector the Simeiz bramh became one of the best equioped observatories in the country. By means of the new reflector highly semitive astro- swctroscoaic investigatioas were implemented . In 192s Sirnei z rrl was directed by G. A. SHain (1892-1956), who was chaser! in 1939 as an academician. The discovery (1929) of the ranid rotation of stars of early spectral classes belongs jointly to him and Ottc Struve. In the Crimea, by means of the 40-inch reflector, .-. C. A. SKair. and V. A. Al'bitskir determined the radial velocitie5 of anoroximately 800 stars. They discovered about 30 new spec- trosco3ic binaries, the majority of which were repeatedly observed, and were investiqated in detail right up to the calcula- ,? - tisn of their orbits. C. A. SHain studied the peculiarities and abnomalit!es in spectra of stars of different types and proDosed theoretical explanations of thase features: ir! the 97

very same period the beginning of his work on gaseous nebulae took place. From theoretical works of Pulkovo astronomers. among them fl can be singled out the investigations of E. P. Gerasimovich on the theory of stellar atmospheres. the interior structure of fi- stars. and s2ellar statistics. Y. A. Ambartsumian. a distin- pished astronomer of our time. an academician since 1953. began his scientific actfoity at Pulkovo. There he carried out an investigation of the temperatures of Wolf-Reyet and 4 Cygni stars, wMch are distirguishea by a rapid outflow of matter from their surfaces; he studied questions of radiative equilibrium of plmLetsry nebulae and more exactly defined the method of determination of the temwratures central stars. Then at Pulkovo arrived N. A. Kozyrev. subseqaently mde famous with notable works on the ohysics of planets and the physical investigations of the properties of time. In 1934 he became distinguished tharks to decisicns of an important and actual problem concerning radiativeequiliwium of stars with extended atEosnheres. V. A. bat, the present director of Pulkovo Observatory, having become the head of its Astrophysics Section in 1938, studied the theoretical problem concerning figures of equiiibrium of double stars. Later on this work took the form of a more general 8 monoeaph. The investigations c mcerning cosmology and the

‘V. A. Krat. Figures -of equilibrium -of celestial --boCles. Moscow-Lenincrad, 1951 . .e theory of relativity (v. A. bat, A. F. Boqorodskii. a. S, Eigen- sm) deserve mention. The educatfonal activity of Pulkovo astronamers was extensive and many-sided. Many of them are read in lectures at the Lenin- grad University and different universities. Students of universities: ad students of the geodesical faculty of the Military- engheering Academy passed their practicals et Pulkovo: young astronomers from many observatories worked on problems; past- graduate students and thme working on their doctorates premred themselves. In 1938 the number of them reached -11. On the basis of the lectures read through at the Beduzhev courses at the Petro- grad Universityr in 1921-1924 appeared :he zotable cmrses of A. A. Ivanovt 'Course a spherical astronomg,' which ran into 3 several editions; of A. A. Selopol'skii: *AstrospectroscoDy P P Gri A. Tikhov: .Aatrophotometry." The two last books were a prcto- tyne of the "Course on Astrophysics andStellar Astronayr" published in two volumes . by a collective of authors under the r editorship of B. P. Cerasimovich in 1934-1936. The publication of such a courser written essentially by a new collective of authors, was once wain carried out in 1951-1968 under the edi- FU torship of A. A. Mikhailov (in 3 volumes). No less extemive was the popularized activity of the observatory. Starting with 1918 nunerous delegations of workers and excursfrms visited Pulkovo @bservatory. At the end of the 1930's the number of excursions reached 400 per year with the number of puests -eater than 12,000 people. The 99

sspularity- of Pulkovo Observatory grew. This ridemread fame appearec! as a result of not o&y the inclination sf the moulation toward astronomical acccmplish- ments. but als3 the versatile and selflese activity of the observatory's personnel. The st&-f of scientific and scientific- technical workers of the observatory on 1 January 1941 consisted of 72 peoole. of which 10 -'re doctors and 18 were cwxiidates of science. This was in general a small collective for that vast

work which is difficult to wholly survey irl so short an essay. A ceremo?lal anniversary session of the Acaciemy of Sciences of the USSR was held on 3-6 June 19%3 in connection with the 100th year of Pulkovo Observatory. No one-surmised that in 14-15 months it was destined to be turned into a heap of ruins. The war of 1941-1945, imosed on our country by the German

Nazis, inflicted meat damage LO soviet astronomy. Pulkovo Observatcry was destroyed to the foundationt it lost all large instruments. a significant part of the library and- many peoqle. At the time of the blockade of Leningrad N. V. TSimmerman. N. C. Ponomarev. F. F. Rem, V. A. Elistratov, V. R. Berg, and many of the observatory's colleagues died; the post graduate student S. S. Petrov perished at the front; the post graduate student .\- B. S. SHul'man and the manager D. E. Ezov died from hostile bomb*lrdment. The Kikclaev hrunch suffered peatly, situated within German occunatfon. The Simeiz branch, ruined and burned down at the time Df the occuoation of the Criwcr, lost its Dear!- the first-class 1-meter reflector. A great ueal came tc be created anew. io0

A SECOND BIRTH

In Seotember of 1943, at the height of the war, an astro- n6mical co&erence took place in IkIoscow. called by the Academy of Sciences of the USSR. All distinguished astronomers of the counizy assured participation in the ccMerence. The fundamental result of the conference was an estimate of the role and significance of Soviet astronomy in the development of world astronomical science and an outline of subsequent actual tasks in the upcoming period. The significance of Soviet astronDmy '-as highly mrldestly appraised, which, in spite of notable accomnlishments, +IC "on'the whole again did not manage to assume A 1.eading position in world science, which Russiafi astrometry played in the second 1 half of the xu[ century." The progress of Soviet astrophysics was also impartially appraised: "The :evzl of practical and theoretical astrophysics in our country is equal to the level in the orincipal European countries. . . However, we cannot oreseptly compete with America in ability in the area of funda- ?ental problems with a principal method, due to a lack of pcwerful equimnment.*2 The insufficiency of equipment was discussed in astrometrical works, although the aitu;ltion in astrometry was better by far than in astrophysics.

e ur 'Astronomicheskii ZHurnal, 1944, V. 21, pt, 1-2, pp. 57-66. 21b- id . 101

As with the extensive damage, almost a push backwards, was the loss of two of the best equipped observatories- Pulkovo and Simeiz. It seemed imminently impossible to return even to the prewar condition. At the same time as the USA established a 5-meter reflector shortly after the Second World War. we were forced to recreate that which was destroyed-in the years of the war. However, the participants of the conference confidently discussed plans for the future, -3efore everything considering the problem of the restoration-of ahe P;ikoVo, Crimean, and Nikolaev observatories. In the difficult conditions of the dissociation of all collectives, an acute shortage of materials, equipmefit and n even foodstuffs. astronomers continued to work at Tashkent, Kitab (Uzbek SSR), Abastumani (Georgian SSR). Kazan aid Alma- Ata, where the cirzumstances of the war and a forced evacuation brought them. Beiiides purely scientific problems, astronomers gave much attention to the working out of questions of defense thematics, having an imoortant significanc- for the country at that time. The organization of scientific work in the war years was highly instructive ar:d merits a wider illumination than is Dossible within the limits of the given book. A conviction in the righteousness of its struggle, unprecedented courage and heroiam led the Soviet nation to victory. Already in Januzry of 1944 Leningrad was finally liberated from the blockade. The battles subsided aT Pulkovo. In February of 1944 N, N. Pavlov was the fir:t to return to Leningrad, 102

apoointed scientific secretary of the observatory. In the beginning of March Pulkovo appointed a commission with G. N. J Pieuimin at the head, who became director of the observatory in April of l9u. In May of the sime year governmental instructions were obtained concerning the working out of plans and a general estimate of the expenses for the restoration and reconstruction of Pulkovo Observatory and its branches at Simeiz and Nikolaev. The war was not quite finished, but astronomers, jointly with architects, worked over plans of Pulkovo Observatory's restoration. With a decision of the Presidium of the Academy of Sciences of the USSR from 24 October 1944, the Simeiz branch wzs chosen as an independent szientific-investigative establishment of an astrophysical nature. The profile of Pulkovo had to bs determined nrimarily with astrometrical problems that took into account the projects of the reconstruction of the observatory. Later on life corrected :11 Drojects and created that profile which the observatory has now. As regards Simeiz, its actual apportionment was included in 1945. On its basin the Crimean Astronhysical Observatory was fciruulated, equipped at the present time with larger telescopes and situated in the

AI- u 4 Bakhchisaraiskii Rdgion in the center of the Cri-ICan peninsula. Simeiz at the Present time is part of the Crimeark Jbservatory. With the selection of a plac, for this observatcry, results of exDedi tion investieations conducted during the war were utilized, and supplementdry astro-climatic investigjtions were organized. Plans for the creation of a southern astroohysical observatory, which Moscow and Pulkovo astroncmers nurtured i.3 the 1920.9 and 1930'8, came to life.

Historical for Pulkovo Observatory was a decree 0,' the Council of Peonle's Commissars of the USSR of 11 March 194,'. in which concrete legislative enactments for the restoration and kec6nGtructim of the Principal Astronomical Observatory were determined. Restoration works we:-e begun in the summer of 1945. Pulkovo was made anew. Before all it was necessary to clear the territory of mines and live shells which prevsntt?d construction works. This demanded a great deal of time and did not Droersss without human sacrifice. Accidents even happened in 1951-1952, when shells and mines of different caliber and type sutldenly went off. However, general observa- tions3 were already resumed at Pulkovo CF 1 Gctober I947 with the help of the Freiberg zenith telescoFe (ZTP). The niorit in this belongs as much to the builders as to the astronomers- observers . However, all Pulkwr,- astronomers longed to cs&? observa- -- tions. In May of 1945 a large group of thc. abservatory's colleagues returned from the evacuation cf Ler!:i:Frad, in >-der*

3Regular observations began on 1 Sept'3rnber 1948, since in June observations were discontihued on tin:e, and +he instrument was dismantled in connection with the fact that with the drainage around the Davillon a live shel.1 of large caiibeL (405 mm) was discovered. to ormize two expeditions for the observation of the total solar ecliose of 9 July 1945. One of the expeditims was directed,to Mount Ivanora. where observations were hamered by cloudy weather, the other, more numerous expedition (22 peoole under the direction of V. A. &st) was situated on P Mount "SoGtavala (Kareliia). There observations were made with success and supplied abundant material for processing and discussion that took tw6 and a--hslf years. .c The staff of the observato&,.greatly thinned out in the years of war, already nunbered 62 people at the end of 1946 (of which 11 were doctors and 12 candidate of science). After t1.e re-evacuation, scientific tpartments and lataatwies4 were disoersed to several locations scattered over the cenfzal part of Leninwad. The dissociation to a certain extent remained, but the colleagues had the opportunity to meet ever) a2y.

4The observatory was then systematically subdivided into six scientific departments: astrometry (N. I. Idel'son), photo- 4 graDhic astrometry (A. N. Deich), the service (N. N. Pavlcv), n" astrophysics (V. A. Krat), solar service (Ea. S. Eigensm), and the spectroscopic laboratory (0. A. Mel'nikov). All department heads had scientific degrees of a doctor cf sciences and ranks of nrofessor 1c5

Lenimad qukKly healed its wounds; life returned to namal. An esoecially watifyiv phenomenon was the fact that the scientific works accumulated over several years were quickly nubiished. A sad event of that year was the suddei: death of J the observatory's director G. Pi. Neuimin, who energetically un4ertDck the reconstruction of the observatory, but prema- turely departed frcm life. H. Pi. Pavlov temporarily directed the observatory. In June of 1947, in compliance with the regulations of the Academy A4 of Sciences. the baoscow astronomer A. A. Mikhailov, member- cor?-eseendznt of the Academy of Sciences of the USSR since 1943 (aczdemician since l964), was selected for the post of NO> Pulkovo Cbservatory director. Henalready known then as a versatile astrormer, a specialis+ in the areas of graimetry, 2 Peodesy, stellar cartoeraphy, the theory of eclipses, astro- mefry, and ac.tronomica1 instrumant makiw. From 1934 to 1960 he was chairman of the All-anion Astron-ini~al-Ge~desi~alSociety, fr-m 1939 to 1363 chairman of the Astronmical Council, and frm 1945 tc 1948 vice-president of the Internaticnal Astro-

Pw noyical Union.5 To the end of his directorship A. A. Xikhailov

'The International Astronomical Union ( IAU) was founded in

19-3 ir, Brussels. The Scviet hion joined the IAU ir. 1935. With the oreanization sf the Astronomical Council in 1937 a national committee from the USSR was to represent the latter in the IkU. Ba~icmembership ir, the IAU is co1,lectlve (inembers of the IAU 106 had abundant exyrience as an administrator. More than once chnsen director, he successfully directed the observatory in the course of 17 years. Having left the hlgh post in December of 1964, he did not leave PulkOvo, and shortly thereafter placed himself at the bad of the astronmical constants de-tment. -e The tirectorship o? A. A. Hikhailov fell ir: a period of exceotiora31~ stormy development and am unprecedented upsurge of zctivity of the observatory: its restoraticn. systematic reconstruction. thformulLtion of new branches and scientific departments. the birth of experimental astronomy. the building of large telescopes, the ride scope of expeditionary investi- ~atims,and the develoment of international scientific ties. The oroject of restoration and reconstruction of Pulkovo

Observatory was carried our ,rider the direction of the prominent

make UD a national coaunitte?) 8 besides this exists individual membership. Of Pulkovo astronomers 11 scientisls were =.embers of the XAU in 1946, and among Pulkovo colleagues at the 1970 conference there numbered 42 members of the IAU. Conferences of the IAU take &ice usually every three years. An executive committee with the oresident of the IAU at the head carries out the leadership with the Unioil. Of Pulkovo scientists, V. A. r" Ambartsumian was chcaer! president of the IAU (1961-1964); A. A.

.? f h .-' v Mikhaj-lov, V. A. Ambartsumian, 3. V. Kukarkin, and A. B. Severnyi were vice-nresidents. 1 07

n architect and academician A. V. SHCHuaev (18?3-1%9). !he n Briullov-tyne classical features of the main building were DrQserved. only the form of the dmes on the central part of the building beim changed. Instead of pol;rh&irons of rood. which cnce tooued the buildiw; iiow sta.d three stone towers with hemfsaherieal metal revolving domes on them. !he interior layout of the eastern and western buih?l-hgs was considerably altered. It subordinated the setting of both buildings: tk eastern one a laboratory. Me western one for administration. Originally, in pre-revolutior&y times. these were in essence

1iv;x-g ~uarters. A dqht- of the western building is the sFlendid two-color ccnference room, finished with red marble with bas-reliefs of Imminent astronrwers, Russian and foreign. In hamonfaus accord w5th the main building is situated a scientific courtyard with observation towers and pavilions, layed out to the sou'h of the main buildirg;. On the side of the Kiev highway the observatory is nrotected by a monument21 cast-iror. railing. The entrance to the territory of the observatory is designed with portals inDoric style, like the north portico of the main building. The portals are ornamented with bas-reliefs symbolizing the zodiacal constellations. From there the view is at once obened to the two story buiiding of 0 the hDtel-hostel (architect D. KH. Enikeev). Encircled with stone railings with vase: and flowers, fountains and flowerbeds in front of the facade, especially beautiful in summertime. this buildiqr r-esembles a Russian country estate of the last century. 108

Asphalt roads connect the auxiliary buildings with the business camlex (the garage8 boiler house of the central heatin+ syster,, the gas controls. the materials warehouse am3 the workshops) and the living q'larters. situated in the eastern part of the territory. The general area belonging to the ob- -- servatory grounds consists of 150 hectares* (before the war 25 hectares). A significant part of it is covered by trees and shrubs and presents itself like a park in its basic iandscape style. On the eastern side of the Kiev highway. where a part . nf the observatory grounds is also sitmatea. the living quakters were built opposite to the entrmce; soutn of them is a grammar school and a largz laboratory buildir~g. erected in 1963. Here is situated the observatory's computer station. with an elec- tronic calculating machine "Hinsk-22" and a complex of other machines. but laboratory aoparatus and new instrumental ideas of astronomers and engineers for the means of observations are mainly developed and realized here. Side by side with the laboratory building are arranged two astrovmical towers of an experimental nature. They are there as if to unaerscore the belongine of all buildings to the observatory. In short, tociay's Pulkovo Observatory is a whole town. the aopearance of which is esbecially impressive to the east -r southeast (in the direction A of Pushkin and in the direction of Aleksandrovka). The construction-restoration works 3n the whole were corn-

~ ~- ~ *1 hectare = 2.471 acres. Clr, bote) i 09

rbleted in 1953. One after mother of the astronomical instruments were again 0u.t into operation up to their terminations the-normal n astromanh (1948). the Tfkrsr -lens camera system of Go C. Sliu- sarev (1949), a @el of the shroapasohere telescoae of S. B. Xoffe, oanufactured on the basis of Interference-polarizing filters (1950), - the completely restored horieontal solar telescope (1951). and others' Astronomers witbott delays began to produce observations. tWng un residence in the ,ccmcrleted south wing of the hotel- hpstel With provisional heat, without water amZ sewers. They did not complain asout the conditiolrs of li-:+, but it was impossible to call them norpal. In 1947 the Pulkovo time service set up work at Leningrad University's observatory. As j'ar baclc as 199-1939 N. N. Pavlov developed a method of photoelectric (autmatic) registration of stellar transits, which essentially ;;.creased the accuracy of determ; mation of astronomica.1 clock corrections5 In 1939-

6The time service took de form of three sectionst the deter- minstion of the correctiuns from astronomical observations, the custody of time, and the transm4!;:.i.on of accurate time signals to users. The first of those mectioned was the "weakest section" because of errors in thr ietermination of the sstronmical clock cc,*rectioM, es;)ecj.d.!.;, because of the so-called Dersonal errors. The introductim ci automatic registration of chservations eliminated these, a:.though it introduced new errars, however, comparatively Fsre easily lending themselves to calculation. 110

1941 regular observations with the application of 'impersonal' registration were produced at Pulkovo. Observations interrupted by the war were necessarily to be resumed as soon as possible for the purpose of the further improvent of the method (in 1947- N. IQ. Pavlov was honored h3th a State"Prire) and were employed with other time. services1 In July of 1953 the Pulkovo-time service shifted its base one.amt -a half years after other deoartments - m and was safely based at p~lkovoitseu. Not long before the transfer of all scientific-department8 from Lenhmad- to Pulkovo, the structure-of the observatory was subjected to reorganisatiron in accorb with the thematics of investigations having changed. Deigense theamtics were phased out; reconstruction tasks were moved away from the second place; first and foremost, observational,:-?: purely astronomical problems moved forward. At this time fcr the consolidation of the Nikolaev r\ branch, the Pulkovo astronomer IA. E. Gordon was directed there ir. the capacity of manager. In 1948 a new brmch of Pulkovo Observatory was formulated- the Mountain Astronomical Station at 0 Kislovodsk, founded by ld. N. and R. S. Gnevyshev. "he principal prohlern of the station in the establishment of systematic obser- LOrQhq vations of the solarbby means of a Lyotcoronagraph. These observations have been carried out since 1950. Together with that a whole series of observations of all layers of the Sun was organized with optical and radio-astronomical methods. At Pulkovo itself the question concerniw the equipment of the observatory for the measurement of observations was keenly in -England, where in 1946 0. A. Hel'nikov aw3 B. A. Oriov went.

However, it woad have proved more reliable to utilise the 008- native industry. which already befare the war had earrle out several experirents, especially after the Uac- lar,ge Solar telescope. In essence. this telescope, with several Improvements in its construction,hk%roduced by e V. Dobychin, was made anew. that, whole series P. - .- Besides a of small and medium sired instk-uments was manufactured, outfitted - not only at Pulkovo. but at other observato&xi. and which provided the wssibility of an oDtical=kchanic+l industry to build up experiments in order to begin the mamfacture of large tele- scobes. m Among this series is the above-mentioned Sliusarev camera (the ASI-4; D = 280 mm, f = 150 cm), the meniscus telescope of Maksutov (=-goo; D-=500 am, f = 650 cm), the Ponomare-.- short- focus double astrograph (AKO; D = 100 WR, f = 70 ca), the Helm- nikov-Ioannislani quartz spnctroglraph_- system (ASI-5; D = 250 mm, f = 75 cm), the Makeutov photoheliograph (D = 100 mm, f = 880 cm), the interferometric heliometer system of the academician V. P. Linnik, his stellar interferometer (first model) , and other instruments. A large art of all this was the means of astro- 112

physical observations. As regards furrdarental astrometrical problems. as in absolute determinations of the coordinates of celestial bodies. for the ti# being were revived the “old horseso- the large tramit instrument and tke Struve-mtel vertical circle. and for relative cietewinations the observatory purchased the meridSan circle of Tafer (D = 190 m. f = 250 cm). a more robern instrument than -the previous meridian circle of Remeld, even to the Nikolaev branch. !The esWshaent of the nomal astrograph at Pulkovo alxowed astmnegatives faglass plates’). accumulated for decades and preserved in-the war years. to be effectively utilized, being of great value for the massive determinations of stellar proper Eotfon8r the theory of motion of planets of the solar system. investig ions of multiple stellar systems and planet- like combanions of stk.’sD and other problems. The largest 2eiss refractor in the USSR (P = 650 mm. f = 1050 cm), also establish& at PuZkovo. was intended for astrophotographic purposes . The less all this satisfied astronnmers, indeed it could pot comoletely satisfy the-. Cea?ands presented to modern astronmy. Therefore, searchzs for new methods and means of observations and their reduction continued and cor.tinue. Several of the instruments established at Pulkovo were created in the ooticai-mechanical workshqps of the observatory: the polar nu telescope of A. A. Mikhailov (D = 200 mm, f = 600 cm) for the determination of astronomical positions, a model of the hori- A scntal meridian instrument of LO A. Sukharev, and the corcnal - slpectro-ph of So A.-&okaf*eva for observations of the s~lar *. earma. Laboratory measuremen? instruments and ether equipment, created according to the plans of Pulkovo astronomers, -re especially numerous: the original level trier of L. A. 4- Sukharev, manufactured Sn five ccpies for different obsexucr- tcries of the USSR, the dbjective micrometer of A. V. Yarkov for accurate pnotometric measurement of plates. the self- n #-- repisterhg isoohotcmeter of No N. Yfk&el*eon. I¶. F. Xuprevich's - instrument for the automatic regrs%ering of the solar spect~. -- tk large diffmction spectropraph t6 the horizontal solar telescqe (5x1 place of the Littrow speetrographl, and the n nozzle to the telescope (the receiver) of A. A. Kaliniak, with

81: fmzqre converter. !lMs rras only the beginning. If we were to enuwrate all equipment creatad in the post-war years only in the ccnstruction bureau and the workshsps of Pulkovo Gbsems- tnry, then at first &ace it can be said that to design and preduce new instruments was the fashion. However, of that mnre wgrks were absr?lutely inevitable in certain areas characterized for the scientific-investigative plan of the observatcry of the nost-war neriod- A new trefid of investigatims brc!:pht to realization in 1952 was the denartment of astronomical instrument making, which was headed up by the prominent Soviet optician, the inven- tor cf the meniscus system, member-correspondent of the Academy of Sciences of the USSR since 1944, D. D. blaksutov (1896-1964). 114

The department had a great significance for the development of instrument W€mg at Pulkovo, but tke main purpose of its orgardsation includt?d the working out of technical jobs for ths erection of a 6-meter telescape, the larsest in the world.* A well horn constructorof astrononical telescooes was ram te these works, later on a recioient of a Lenin prize, B. K. 10annishn%~A great rme in the works also belonged to 0. A. -- .- m taeI;n&kWW I60 NO 1Ukhele8~n8to wham was passed on the maqage- &nt of the department of %nstrnuentmakine: after the sudden

- death of Do D. ~al~8utov~Also the3 were begun site searches for the erection of the future astrophysical observatory with the largest telescope. The early action taken was not unneces- sary; exped;tionary astraclimatic investigations carried out c under the direction of N. I. Kucherov (1905-1964) took up more than ten years, Seven scientific departments and two branches (NiknPaev and Kislavodsk), about 90 scientific and scientific-technical ca'leaeues (with a Tenera1 staff of 2b0 people), newly em- structed buildiws ad outfitted labxatories, 20 operating instruments for the oroduction of astronomical observations and ten having been imqlenepted only d.;rinE the post-war years of serious investiaations- such was Pulkovo Observatsry at its official openine: after the restoration. At the same time was established the *Pulkr>vo" seismr4ogical station- one of the best equippen stations of the Institute of Physics of the Earth of the Aczdemy of Sciences of the USSR. The cerenonial a~er~inf3of the restored Princioal Astro- nomical Observatory of the Academy of Sciences of the USSR took ola-e in May of 1954. A special session of the Department of' Physical and Hathematical Sciences? of the Academy of Science8 of the USSR was devoted to this event, having taken place on 20-23 May in Ler.imad and at Pulkovo. Besides members of the Debartment. over 500 astroncners and geodesists from different observatories and establhhed countries, PuLkovo builders, representatives of the Leningrad pcblic and academicians of the Union of Republics attended the sessPon, and also 47 fcreign scientists from 18 countries, including the general secretary of the IAU, P. Oosterhoff, who read greetings of the then-time president of the IAU, 0. Struve, great-grandson of the founder of Pulkovo Observstory . Those wh? asseRblzd- wamly saluted Pulkovo astronomers on the occasion of the second bi.-th of their observatory.

7 In 1963, from-the structure of the Department of Physical and hlathenatical Sciences. was formed a number of new departments, mathematics, qeneral and anplied ohysics, the degartment of Earth science , and qthers. The Princinal Astronomical Observatory became a oart of the DecartmeRt of General and Agplied Physics, which soon after wis ?e ict!T.e;! +:?e Departine:it of Ge..ecal ?hlrgir..c;

&I,.; A.Fc.rl:n.?-y, 116

TRAUXTIOKS hi NOWLTY

Fcur years later Pulkovo Observatory again received visitors. Teeth IsAugust of 1958 in Moscow the 4 conference of the IAU took place. the largest of all previous conferencest over 1200 delegates and visitors from 35 countries. of them 778 foreign astronomaars, uho showed great interest in OUT country. The launching of the first artificial satellite of the Earth (AS) in the world, realized on 4-October 1957, demonstrated the strength of Soviet industry, the high level of developen%-of science gchnology in the USSR._ For astroncmical science this sigzified the birth of a new area- l exnerimental astronomy. The peculiarity-of the Moscow assembly was such that it happened in the period of the International Geo- #hysical Year (ICY), the most grandiose scientific collaboration

'Astronomy. the oldest of "he sciences, for centuries remained primarily an observationzl. science. Orly meteorites having hit the Earth frm interplanetary space can be touched. Everything else beyond the llmits or' the Earth remains inaccessfble to direct study. To bring nearer the means of observation to celestial bodies became possible thanks to rockets. automatic stations in the cosmos1 and piloted cosmic flights. What is more, by means cf oowerful rrlckets it became pGssible to create artificial celestial bodies. This signified the birth of experimental astronomy. of scholars of all countries of the WOL*ldm / The foreign delegates of the conference were invited to visit Leningad and Pulkovo. By that time Pulkovo was even more rebuilt thanks to the organization of the station of optical ob-

8ervatLons 3f the ASE (1957). and the department of radioastro- nomy (1954). mw instruments were established ciurir?g the ICYr % . mtable was the construction of the large hlkovo radio-

1 (URr 1956), the largest radiotelescope in the world

+ .timeter wavelengths. To Pulkovo fell the great honor to receive the most notable astronomers in the world within its walls. In its guest bookr opened by the president of the IAU, A. Danjon, appear hundrsds or signatures and notes in many Ian- guages. A broad opportunity of establishing personal ccntacts with scientists of other cour.tries was presen5ed to Pulkovo astronomers in these days, and the establishment, of the exchange of minions, the reception of advice and critical remarks m the side of the greatest authorities in the world. But the critic;sm was exceptionally business-like and well-wishing. During the days of the confeyence and for a long time following it, testaments of thanks and articles filled the Soviet and foreign press. So the participants of the conference aporeciated the hosoitality of the Soviet ,qo7iernment, the Ac?.demy of Sciences of The USSR, and soviet colleagues. The wide contact and collaboration through the IAU, eopecially with scientists of *xialis.ccountries, became habitual for Pulkovo astroncmers in post-war times. Many of them in turn were chosen 118

preslidente and vice- presidents of different continually existing

commissions of the IAU. In 2952, P+ the VI11 conference of the IAU in Iiome, a special symposl-m, "Problems of astrometry of fnint stars," was conducted on the initiative of Sov'st astronomers. Reports of the Pulkovo astronomers M. S. Zverev and - A. N. Deich were-presented at it which affected the state of the-psablenk of %he Catalog or" Faint Stars (CFS) and wh;ch main-

creafkon -of this --&ct&l~catalog. Tlje proposals were settled -_ .. . Generh :& .a rekohmendation--. of the -. . - ..

.c ggerene e...$a 53h observatories in this . ,

.wQfk; Sc&ntis%s.. of soc-ialist countries rvtL-e the first to respond; Polaqd- and &ms;n€a. Tie 'Wroclaw and Eucharest 'obser- ~. ._ vatories were included in the ger.eral program of o5ser7ratinns. The prceram of the CFS was recognized as international, but organizational arrangements were still discussed in ccrrespor.dlng ic ccmhsicns of the IAV. At the following conference of the IAU, wLich took place in Dublin in 1955, a final understanding was achikved on the basis of a merger of Soviet and American ?ro- posals: the crogram of the CFS was consolidated with an inter- natimal undertakirg according to the reobservation of reference

stars of the zonal photomephic catalogs. The cms-? idated prc- gram prrltided for the observation of over 50,000 stars, the cqqrdfnates cf uhich were subject to determination froin meridian observations. In the followifip several years these 03servaticns were intensively carried Dut at 11 observatories of different countries (Washirigton, Greenwich, Paris, Heidelberg, 3ulkovo. Nikolaev. and others). Especially important remained the or- =:A iation of analogous observations a-r; observatories of the Southem hemisphere. Because of the very small number of ob- - servatories in the Southern hemis?here, its sky was more incom- nletely investieated than the sky of the p;orthern hemisphere. Therefore, at the XI conference of the IBti, which took place in Berkeley (USA! ig 1962, a resolution was passed which pro- vi.ied hope at the Washiqton (Na-;al) and Pulkovc observatories in relation to thz devel-rsent observations of southern rgference stars (SRS). Crra or” the principal participants of ”;his new wo?k was the Chiiean expedition of Pulkovo Observatory. Jt Pulkovo itself, obsemational work developed in all directions . After. a thorough irrvestietion of the instruments, inevita3le because of the prolcngea interruotion in their func- %ionin& observers on the large transit instsment and the vertical circle set about to work on the coEpllation of the next absolute catalofrs for the eooch 1955.0. As already stated, the new absolute cataloes contained alnost twice as many stars as the orevfcus mesr besides the bright stars of Struve’s 0’ ram, fundamcntal faint stars were ir.c?uded in the proaram of absclute observaticns The general number of them was 1046. Thus, -3; trad: tional oromam was essent rally rerovated and would enta great difficulties for the CPS, which was pivclta: Ccr Pulkovo astromctry of the nresent Deriod.

Almost simultanecgsly lrvjth this WP~beeun observations with 120

the meridian circles at Pulkovo and Nikolaev of stars for the ir,ternatimal program, the so-called AGK3R- reference stars of the northern sky for *e recbservation of zonal catalogs- Pulkovo took on itself the determination of the coordinates of ll,5OO faint reference stars8 W-ikolaev- 10,000 stars- The processing of the observations was carried out jointly at the Pul- kovo and Washington observatories- The question must arfser was the intema*ional cooperation with Soviet astronomers in the creatlon of the catalogs of faint stars required.for it, if Pulkovo Observatcry only, to- aether with its branch at Nikolaev 8Rd the Chilean expedftI@n, made observations of the whole sky and carried them out in a comparatively short the? The point was not to "seize the initiative"; it was enough - that it belonged to Pulkovo @bservatory. The question, in essence, concerns the creation of the foundation of astronomy of the XXI century, and the majesty of the problea immensely increases resoons;bility. It is necessary to determine the coordinates of a huge numSer of stars with the greatest precision attainable in modern conditions. With the point of view of the next century the insafficlent level of development of astrmomiczl measurements could accomdste a large quantity of oarticisants for the work. That is why the greatest mmber of observers Dossible was expediently drawn into the work. The substantial number of Darticipants raised t3e accuracy a?a soed

UD all works. But this is even more imocrtant because the 121 determimtions cf stellar prcper mctkns enter intc fundarter&& determinations. except for the mezsurenent of coardirates, and the sooner the firrt wrt of the or3gx-a~is carried Out. the earlfer the second stage can be started- ultimately- the rsduction of prober m?tior.s. In 1964 the number of obsematorfes- particimts ir3 the implementation of tlge tasks reached 25, -- on the dale globe, in the Northern and SOU-~~hesisgheres. -..

Pulkooo Observatery solidly retained --e hGtfa$hre Ebt ~ '.-- ' only in an organhatianal mode (through a cdssitm of the IAU and the Astmmetriral Cmmission with the Astl.onom5ca.l Councill- - h of the Academy of Scierlces of the USSri). buf a co_netzqt.- &is- ~'layof a 'personal example' in-the work. ~Beforeall or' this ms the sco3e of astrsnetrical and astrophp?c&phic rsrks : ths quantity of observatians, their reduction, the cr,w.ization and omducticn r>f observations in the Soutkerr. hemlschere. Hany facts of nc small ccmseouence were dealt with. In 1956 the 'Pre- 1;acnary Summary Catalog of Fundmen+al Faint Stars with Cecli- nations from +90 to -20" (PFCFS) was prsduced by LL. S. Zverev and n- D. D. ?olnehectsev, base5 on zbse&-vatlcnsover tk.o ccurse cf 15 years at 10 observatcries, of which tn. were fcreign- Eucharest aRd Wraclaw.' This catalog, computed ir. a short the sm. with the zarticlontior e? the Instftute of Themetical Astronmy (ITA) in Le?irrPrad, made man.ifest the fact that it had a direct relation to the ercblem of the ZPS (one rore sanple for duplicaticn)

7 'Trarsactions of the Princioal Astrcnocical Cbservatcry, v. 72,

195s e 122

and compared with a numbex of the first fundamental catalogs directly produced at Fdlkcro. Until then the 'monopolies of pmciuction" of furrdamental catalogs belonged ta-German and American astronomers (A. Auuers, A. Kopf, L. Boss, B. Boss. H. Norm). A year earlier a cmplete series of fumamental catalogs for one coordinate- right ascension- was completed. These catalw wen the result processing lukdertrrLren by A. - of A. Wnriro of the 100-year sequence of dyemations (1839-1939) L on the large transit instrument, For the iirst time fundamental catalogs were created on the bzsis of observations of great precision. oroduced on one instrument. The dream of W. Struve was indeed realized! True. advmcing the plm of creation of strictly absolute catalogs of stars, the founder of Pulkovo Obsemitory supposed that this tssk would be accomplished on one instrme,rlt. But the task (human practice in the rather wide sense) == carried out by wy followers of the Pulkovo Wertaking, a.d A. A. NemlrQ,, for the construction of the Catalans themselves. of course utilized summarized experiments of other observatories. In oarticulzr, it was advisable to utilize generally accepted internat!onal values of fudamental astronomical constants. but corrections to them were outlined concerfiing the necessity cf imorovenect of these conventional values. precisely in the direction to which they were subsequently changed by the Hamburg assembly of the UU. For the determination of astronomicd constants a joint arillysis of absolute observations uf right ascensions and de- cllnations would be especialtp valuable. Em A. Orlov (1906- 1963) underto& to carry out analogous work on the gemralfzed 1QO-year sequence of observations with the Struve-Ertel vertical circle (aasolute observations of declinations). His death €n+*?rruptedthe work, which had not reached the mid-pcint of the projected task. me work aw&&ts3&W.her-execrtterm It genere-rsly returns his kindI=ess, all the more now that, with the publication of a new absolute catalog of declinations of d 1955 (G. S. Kosin, E. K. Bagll*dinskii), material became far mare extensive and richer. One theoretical investigation winmerits attention- one more €a* of the 'personal examnle,' After the exanmle of the PFCFS, over several years it would be possible to set about to the construction of a fundamental system of stellar coordinates coverinn the wh5.s sky. However, for the southern sky the observational material was clearly insufficient. Considering this daficiency, Pulkovo Observatory took on itself the completion of the processjng of absolute observations carried out in 1928- 1941 at the Yelbourr-ie Observatory (Australia), which in 1944 ceased to exist. The omoosal concerning their reduction ori- g;na+ed from R. Woolley, present-director of Greenwich Observa- tcry. thrwgh which all material of cbservations was obtaimd. The orczraxn of Melbourne observations on the whole cc.?tained stars of the Baklund-Hoff list (almost 225O), and also stars A of other lists. K, N. Trtvastsherna directed the processing of material. The first par2 of the work was.comoleted Bubj. published in the farm of a separate publication. In 1960 the abservations of 11,500 stars of the international Dro- and the absolute determinations of the coomii- nates of the 1046 briaht and faint stars were completed. Several years were required for the fhal reductioird the observ8tions and discussion. Nore quic)tly of all this was done accoAik - -- the works of an hternational character, regulated obligation, and strict time constraints. However, the observers on the large transit instrument and the vertical circle almost at once were involved-in new crucial observations with the aim to determine the msitions of the large planets, -*hich ues dictated by the necessity of a-more precise determination of their crbits and the theory of their motion. so important for a calculation of accurate trajectories of flights of interplanetary space stetions. The practical significanct of the astrometrical irrves- tigations regenerated earthly goals: astrometry became useful for cosmonaut ics . Topether with that a serious oroblem of the further increase of accuracy of astronamical observations stood before astron-mers.

In soite of the fact that the accuracy of the observations “0- duced at Pulkovo was sufficiently high, new problems oresented scientists the necessity to accomolish a 10-15 fold increase in accuracy in a single bound. This was possible mly on the basis of a radical reformation of methods and a complete raplacement of instrumental equiment. Along this line several works were ------_ -- already corJucted at Prr2hmm-ule .ara;lirrrcturs of the horizontal e meridian cfmle of L. A-'sukftarer (at first in the form of a madel, then- a rrerking des-), the photogra#tic vertical circle of DL S. Zveriv, the large transit instrument for the Chilean expedition with concrtructioaal improvements introduced by A, A-

Nemiro-- It €8 possible to detelrine the subsequent progress 4

- d* Zh$eed, traditio-t Pulkavo Observatory are contained not 1 ptlation of s'iellarcatalogs or the determination of astroniwical constants). but also in a canstant perfection of zblaeth035 of aproach to these old problems. Perhaps Struve had not found a comoletely new method of a&proach to them. 'phis was a particular tradition because the novelty inwardly inherent to it was this tradition of novelty, However, here is no passion fsr novelty for the sake of novelty: everything was subo-rdinated to the "vital principle' of strictness and accuracy- the principal de- of the Pulkovo astrometricdl school. Let us turn to another traditional problem- the determfna- tion of astronomical constants. As is evident from the foregcing, scme astronnmical constants are obtkined lrom "themselves." in essence, f-on any number of observations, but still W. Struve presented the task of their special determination from ooserva- tions with the tra-sit instrmmt on the ?,rime veTtica1. The

n '- Dol- telescope of A. A. Wikhailov served thf3 very purpose at 126

r\ post-war Pulkovo. After horavements in+raSuced by Eli; I. ?otter into the method aml the proeress of obsemtions (a semiautomatic control with the photoeraphing of the cimurpalar region of the sky. a dffferentiated measurement of temperature. and a mintenance of the stability of the €nstrment).the processing of a T-mr sequence of observations (1953-1959) resulted in a value of the abemtional constant of a:Wse which is extreme- close to the value reconended by the Hambm asseablp of the IAU (2034%8). Later. in turn. it was based on the results of radio locatian observations of' VemsS3 carried out in the USSR and USA in 1960- 1962 . The aberrational constint was repeatedly determined at Pul- r?- kovo bj several acthors (V. S. Bedin. N. Y. Bakhrakh, N. N. Pav- r. lop, C. V. Staritsyn) from diverse observations, in particillar from sequences of observations ofwtime service. The ct?nstar,t of nutation was sufficiently dependably determined from latitude observations. Thus, as a rerult of the processing of an extensive sequence of observations on the Pulkovo zenith telescooe fn 1915-

3 The radio location of Vews allowed an accurate distance from the Earth to Venus to be determined. consequently, to more accurately determine the measure cf the sclar system. As fellows from the concept of aberration, an accurate value of the distance frcm the Earth to the Sun and the megnitude of the velocity of light gives the possibility to calculate the aberrational constant, which was done on the basis of radio location observations. n 19L. S. V. Rownskaia (1886-1969) obtained a value of the constant of nutation of 9120B18 which appFoximates the best determimtioae. for examole the determination of B. P. Fsdorov (Po'ltava). and. probably iridicated the necessity of a mre precise deterrinatioa of the international comentional value. However. the question collcecnlng the iaprovement of astronomical

carrs-br is lpot decided onlp on the basis-of astronanical data. - - - Cqnsfants are relat@*through their mathemmticcll dependences.

- . I_- - - - aeace of tG ibb&&G&~ c,-tarit tm~the solar m. A more complicated theory connects the constan~sof precession d' nutation with the mass of the Noon. !Fhe determination of the gmerally accepted values for these quantities can be mutually fn accord. This problem proved to be exceptionally difficult arrd still remains unsolved. The determination of astrocomical constants was closely

connected with the study of the Earth's rotation. 'phis problem acq-aired a snecial hocrtance during the ICY. The systematic stud3 of the Earth's rotation produced twc services- time a4 latitude. At the beginning of the IGY both services were -ready for action*t the staffs were made up and trained, instruments were acquired, observations were produced accordirg to the compre- herrsive Drom-arn. With the aim of the investigation of instrumental errors and the influence of them on the results of latitude determinations, a second senith telescope (the ZTL; D = 180 mm, f = 236 cm) was eTtablished at Pulkovo in 1957, manufactured in 120

7 Len€rrP,rad on the basis of constructional plans of V. I. Sakharov and I. P. Itorbut-- The idea of parallel observations with two renith telescopes. presented ard for the ff-st time realized by PUkovo astronomers, won recognition in a number of observatories (at Poltava, man Kitab, then at foreign observatories). In 1967 a 19-yeesequence of uninterrupted latitude observations by raeans of Me Z'PP, started in 1948, uas finished. After thfs tire, covering a whole nutational perlot¶ (18.6 years). '88.000 VeasuFerents of €atitude were obtaiw. a good half of rhich wetre laken in the 6-year tirre' span (1955-1961) of observations for the comprehensive Dropam. The "density of obsema- tiom' after thts time span exceeded the density of observations of 1915-1928 by a factor of two, also carried out for the compre- hensIve oroaraa. But the principal thing was not the quantity of the observations. The traditions of Pulkovo were kept sacredly; the Pulkovo latitude service produced the best results in the werldt the accuracy of its observations was almost twice as great as the accuracy shorll in any of the stations of the International Polar Yotian SewCe (IPMS), the number of absematories of which now taking part ia about 40, scattered over the whole terrestrjel globe. 0bservatio.m of "high density" play an imoortant role in the study of' short-period variations of latitude. So, from observations of 1915-1928 a "daily term" with an amolitude of OtO4 whs revealed. The processinp of a new set of data, begun by L. D. Kostina , led to the reduction of the amolitude of the daily to OZOl5. This processing was carried out under the direction r) of V. I. Sakharov with t.he application of a new isiethcd, according to the utilization of a more precisely determined value of the aberrational constant and with the calculation of all oossible corrections recommecded by the Astrmomical Yearbook according to the execution of a reform of 1960 in the computatioa of the so-called reduced magr?ltudes. All results of the processing of the new lg-year sequence of observations are still difficult to foresee but they undoubtedly will be interesting. The results of the observations of the latitude survey were remlarly communicated to the Soviet center (Poltava) arid the intell-natimal certtsrs of the IPXS (Mitu-u~, Paris) However, lat: xie n%ie-Lu;tions for a long time exceeded the limits of

Durelp “3 .c’s’, zoals.“ These observations give broad scientific m-a-c!+lz:. for the decision of such Drofound (in the direct and figurk.*ive sense of the word) problems as the study of the “viscrsity of the Earth,“ or, for example, the interaction between the terrestrial core and the mantle of the asolid” Earth, set in rotation. So the practice gave birth to a theory, the develoDment of the theorjr was subsequently required, nore often of all of +he modified oractice, and a new practice sugzested new theoretical prob1en.s. Such transformations continuously haor-ened with another astronomical oractice- the time service. According to a number cf reasons the Pulkovo service was not resumed with radio cram- mission of accurate time sienals, rather, ccncerning: its activity on the reduction and perfection of methods of the astronomical determinatian of time. There existed the difficult task of the assimilation of the "lagEing section." Here arose a number of almost insurmauetable difficulties, which turned out to be quickly circumve-ted, rather than to be overcome, changing the methods of combfnation of theory and practice. With the introduction of an automatfc-method of observations. attention was dkected to -. the study of Instrimenta-1 errors and ths influence of surrounding conditions on +he accuracy of observations. With the works of V. M. Vasil'ev, the influence on the precision of observed clock corrections-of tkr differences of temoerature of separate parts of the instrument was proven, and also the local difference of temDerature in the dome. As with other authors, the specific role of local refraction and the effect of wind was shown. To create the theory, to calculate and introduce comer-onding cwrections in the observations was not shown psssible. It remained to be attemted to chance the conditions of observa- tjons, in order to decrease errors, of course, having in view the determination of a "theoretical state of affairs." With this aim N. N. Pavlov Dror.osed a25 built a new (in the constructional sense) transit instrument (PTI) with thermal 4 imulation -!nd other imnrovements. In 1959 observations by

4The Pulkovo tramit instrument (PTI) was cmstructed and ganufactured in the mechanical wnrkshons of the bb=;f'*I t)5SrobCmicq)

d hWrVsfQr7 with the utilization of the main parts from a means of the P!Pf came to 38 produced in a large separate dome with -. powerful exhaust ventilation. The flow of air exiting through an open hatch of the dome and flowing arouiid the instrument eliminates local differences of temperature in the dome and

partly reduces the influence cf outside wind. In order to avoid local refraction the instrument is raised under the roof such that the objective end of the-hstrument is situated at the Zimits of the dome slit in the presence of the open hatch. These arrargements curtailed errors of obser&tions almost by a factor of three. Such an imoortant practical result influenced the determination of theoretical questions in an astronnmcial aspect . The high precision of the observations was also the result of a res;. d105 of their quantity. The more determinations of some magnitude that are produced, the more trustworthy and accurate would be the knowledge abmt them. After only 10 years (1954-1963) the time service at Pulkovo observed over 82,000 stars. At the time of the ICY the proqram of observations produced by the Pulkovo service and carried out by many time services of the USSR contained about 500 stars. The list of stars was sne- cially expanded for the calculation of catalog purposes. At

Hildebrand transit instrument. Presently the manufacture of another, more modern transit instrument construction has been comoleted, the idea of which was also intmduced by N. N. Pavlov and carried out in the workshops of Pulkovo Observatory. this time the collective of th? department of time service already had gained the experience of the compilat'on of stellar cataloge. In the process of the "service" with the photoelectric method, ljzssbges of the same star were systematically observed, thanks to which it was possible to reveal the errors of the catalog positions (for right sscension) of the observed stars. The objectiveness-of the methM and the repetition of the process of measurement& allow these errors to be determined exceDtionally accurately. In such a way eight of the "photoelectric catalogs" (Pl-F8) were put together, which were distinguished by a high precision. Especially valuable was the summary catalog of right ascensions of 807 stars put together 0 by N. N. Pavlov, G. Y. Staritsyn, and P. M. Afanas'eva- and based on twenty separate catalogs of nine time services of the USLR. The number of observations used in it exceeded 185,000, of which 80,000 were prnduced by the Pulkovo time service. According to its precision this catalog exceeds the best modern fundamantal catalogs by approximately ac order of magnituue, L.2.) by ten times. Cataloas of stellar positions were a traditional aim of scientific investigations conducted at Pulkovo since the ky of the founding of the observatory, but in the given case this was not an enti in itself. As far as observations of the time szrvice directly reflect the phenomenon (fast) of the Earth's rotation, tha+ opens the Dossibility of study of the means of eu 'dy rotation. "Clock corrections," which were obtained from astro- 133

namical observatiocs may characterize both the irregulmities of the matfon of the clocks and the irregularities of the Earth's rotation. It is necessary only to be assured that the laboratory clncks are sufficiently accurate. Until comparatively recectly there was no such assurame, and the direct method of study of

the irregularity 02- rotation by mans of a comparison with labcratmy clrzcks remained bapplicbble. although the irrepu- larlty icself was an estahiished fact. Tnus, from fne theory of tides and tidal frictim. slabcrated by 6. Darwin at the end of the XIX century, it followed that the Earth must have a secular re-Lxdationof cotation. It was really manifested in the form of a lack of coincidence of theoratically calculated moments of the beginnix of solar eclipses with the factually observed mmezts, from which the magnitude of sloninq

2 -:-dual increase of the neriod of the Barth's rotation (a dcy) which amounts to O.OO23 seconds in a century- the magnitude still inaccurate in direct verification. On the basis of the theory or" motion cf the Moon and several planets with an analogous method, Log., *ram the comparison of Drecalculated oositions of celestial bodies with observed values, uneven varistions af velacity of rotation of the Earth in different years were SUS- Dected. The createst (to 0.004 sec) deviations of oeriod from the "no.ma1" r9 observed in 1897 aqd 1920. It was supoosed ti-at sitch variations happened with a "leap" on the side of an acceleration or a deceleration of rotation with a gradual return to the noraal temo. however. the 'leap' itsex was not revealed at once on account of its minuteness (the chzuqtge tf the pertod of rotation did not exceed 0.001 sec in 24 hours). and was revealed over some tire as the result of the accumulation of error due to the mabnomala velocity of the BartWs rotation. After the imrentian of quartz clocks (in the 1930'8). 8easoml vartations of the velocity of rotation of the BaEM_- uere diseovered with a direct mthd. As it turned out, the duratfan- c3f a day could deviate from the average value by more than 01001 see. the I.. Earth rotating faster in Jurue-August than in Decerber-~ecmmry-~ 1 Queclocks keot time much reliably than the best p~rrdi23-JQ clocks used UD to that time. The daily ckiarm~of quarts clocks dLd not exceed 0.0001 sec. A new stage in the Msttgation of the irremlarity of ear';hly rotation uss begun with the introduction of the more accurate. hi@ pre\*isionatomic (or molecular)

C1CCkSb the first exarroles of which were crjnstructed in 1954-1956. Tho ICY nroerram sttmlated theca investiwtions. ihe orecision af the motion of laboratory clocks is now confidently controlled with the heh of 'atomic standards." Changes of the duration of the day on the order of 0.0001 sec can be easily reghered. if a method of comparison is allowed- astronomical observations wLich give an accuracy of only 0.01 sec. That is why this "intermeaiate link* came to lag behind, and the success in the uerfection of astronomical observations opens the oath to a detailed investimtion of the irregularities of the rotation of the Earth. However, the stady of the character of seasonal and umven irrephrities, espechlly the cause M their origin. was shwn to be a eaafksion of -rm 3he Rench astronoaer A. man (1890-1967) atterottd to caordhtt the uneven chantips of the velocity of rotation of the Earth dtR the optbursts on Sun~ob158FIcd in 29s 8mB 195% or aecapa-yiag pbemmmt- solar cormscular winds at??-tic stom. %%e connection rfth outbursts am sow wtirity has now been demonstrated- In earlier works W- Stqko (France) discwmred ck-8 af the 1QW:tude differences btreen Europe ami North A#rica, which bore a seasod character, aM alsc were associafed ri*h - the neriod of sclsr activity. Hear the maximum of the activity Burme -and America were closer, near the riniau further away - from*& - b+her by several meters- H- W- Pavlov turned his atter.tion to this curious result

ad confirred it in modern, =iT accurate ad more extenzhve material, offering data of o3servations of tine servicescattered over different continents. What does it mean? Time services wxher astrcnmical observations and, in the limits of their accuracy, systematically register the duratiorr of the period

cf rotation of the Earth. The *\-.saltshorn depends 01: the time of par, the nhase of solar tictivity and, finally, on which continent the observations are produced. If the velocity af rotation of the Earth is registered differently on different continents, then before a17 it is necessary to find scme averwe velocity, taktpg into account that fact that iill services do not observe identical'y accurately. The nroblem has many uncertainties. W- No Parlor attemoted to refine the raterial. after which he was comilrced that the oscillation of the differences of 1mgitude betueen contimnts dtd exist. Supposiag th pbmmekn to be real, he explained mbllity of the earthly cmtinent8, which is expressed in their 'oscillatoryo dismlacenent fhm a relctively average positicn. Ms'oscillatory aetion' rrga_cmnected ria the ecceleratiun deceleration of earthlJ r&atSon ad. mu.is erphined as a result of an exchange oi rotational energy betreen the Crarthly core a& the atrrosohere, the condition ~i wkfch is characterited by changing circulations, depelviiag an the fhe of the year ami on stormy nrxesses on the Sun. Go- further. N. No Pavlov cumpare0 the detected displacements of the cc~ntinentsri$h larw earthquahes and discovered tht the catastrophic Chilean earthquake in of 1960, accor- dim to European a-3 American time services, was preceded by a5 ahorml shift of the American continent in the direction of the South Pole and amouting to 14 meters towards the Chilean coast of the Pacific Ocean. Does thio Rot mean that data of the Earth's network of time services (which further amounts to the title of "Earth rotation service"). it is possible, some time can be utilized for the prediction of earthquakes? From the foregoing discourse it is evideet that for the measurement of times it is uossible to avail oneself of other Deriodical phenmena, for examnle, the motion of the Moon. But here also arose the question about the urecision of the observa- tiansr as far as the observations would be accurate, as far as lam intervals car! be reliably %easured off.’ Of course, the sienificance and the theory of acltion of the Moon are pzrt of this question. Consequentlp. side by side with the measurepent of time, such observations can be used for 2 more precise determinatim of the theory. Por these yrwses the positions of *the Moon are otscrved b3- a photogmp!hical method with a s-cial camera.

I. The camera which gave the best risults was invented by the Amzri- caq astre mmer V. Harkowitr. An instruaent of that type was

b manufactured in the mechacical workshops of the Pri-mipal Astro- nolgical Cbservatmyt the nethcd of observations -was wcaed out by fl KH. I. Potter. The accuracy of the cbservations at Fulkovo was shorn to be high. The probabls error of a determination or’ the cacrdlnztes of the Moan fro& ctsservaticns on 0r.e sight mounted

Observations of the cositfons of the Blocr. cm afsr be used far PreQ2esical nur?cses for the measurexrt ~f large arcs or: the terrestrial si-lrface (the distarces Setween remzte pcircts). r\ Accordine tc an idea of KH. I. Petter, m- exceditioral astrczra?h was built in 1962 by the Prfnc’pal Astroncnical Gbservatory fzr oh?tographiral aSsezvations of the Nom: it was utilized in a number of exoeditims. For the measurement of the cccr2inates of the N?OR on phrtoxaghic -lates. an autrmbtlc measwing emine was 5ccrzmd by S. PI ~YS~~*CY,which gives rhe results af the masurere-ts cn sunch cards for subse;!Aent ccm mtat iwal

Except for -ur natural satel’lite- the bbon- observations of artificial satellites of the Wth (mt'sj are used for the reasurement of large arcs on the terrestrial surface. Created by the hands of peoule. thase "celestial bodies' are distinguished from the remaining celestial objects not only by their artificial origin, but by other features, in particular, the - quickness of motion on the firrament. me first observatioltrr of them gresen3ed themselves an unusual matter. The photography of their tracks was especially complicatedt these were Taint, BUS quickly moving, celestial bodies. Because of their small dfmmsians they were faintly illurinated by reflected sunlight, but because of their nearness to the Earth it was only possible to observe them in twilight, when the sky was still comparatively liet. The effort of photoqraphiw the paths *cC meteors was slmst ina?,olicabler for-ASE's a high precision of the deter- aimtion of their coordinates follows, otherwise the cbservations lose their meaning. Originally observations of As's were oroduced on the whole by a visual method with the help of a special scope (a small telescoue), possessing a substantial field of view (3 = SO mm, 0 11 field of view with 6x magnification). The Astroncmical Council of the Academy of Sciences of the USSR organized over 70 stations of optical observations of ASE's Ln the territory of the USSR and socialist coufltries. Such a station, containjng

UD to 20 observers-volunteers, was created at Pilkovo. In crder to assure the best survey of the assumed route of an artificial sate! lite, observations were produced simultane-usly by 6-10 139

observers. The satellite, mpickedupm by one of the obsemrs,

was oattachedmto ariy star observed in the scope at that very rasrant. Z!&e time of the mattachmentm was mgistered rith a

C- C- ph by neans of a pressure key. The error of the obser- nttoxm irom the best obsemtories aaounted to O?X in single iilld 0.2 seeomis of-time. Perhaps this is too great an inaccuracy, we consider in one second distance of if _-- that - the asB travels a about 8 Ira- -For the first time the photograohic program of an artificial satellite (more accurately, the rocket-carrier of the first Soviet -- ASE) was obtained by F. P. Kiseleva- at Pulkovo on 10 October

195?-.by means of the short focus astrograph AM), khich subsequently used for systematic observations of AS'S. But these observations demorstrated the necessity of the creation of a special came:- with a faat acting shutter. In the capacity of sgch devices light gathering cameras were utilized :rIth special mechanisms for the accurate registeriq of time. Although the work far the orgaFization of the observations of ASE's was oroduced on the whde by the Astronomical Council, a larere role in the matter of the improvement of apparatus crd the increase of !recision of observations belonged to Palkovo -a . n aatron-mer8 (A. A. Mikhajlov, D. E. SHCHegolev, L. A. Panaiotov, Bo A. Figaro, G. V. Panova ). The methcd of reduction of the v Dhotoeraohic observations of ASE's was proposed by A. N. DeLch and A. A. Kiselev; the laboratory of scientific photowaphy, u directed by I. I. Breido, was occupied with questions of the 140

increase of sensitivity of photoemulsions. Ijr 1965 the number of thotomDhs of satellites produced at Pulkoyo still eaceeded a thousand. The precision of the registerings of the moments of observation reached 0.002 sec, and the error in the determination of the position of a satellite did not exceed 9.. Such an accuracy allowed them to avail themselves of observations of satellites for a so-called cosmic triangulation. !Che geodesical connection between two or more points on the Zarth is accomolished with the help of triangles, the bases of which are based on the Earth, and one of the vertices, comon to all triangles, is situated in space. This is an orbiting satellite, obse-ved Prom those points which we cm. "connect," I.=., determine the distance between them. According to this the main thing is the synchronization of observations, then a picture at the moment of the observation makes it stationary, which simplifies the calculation. The synchronization could have been ensured with tne help of soecial geodesical satellites with impulse lamp flashers, however, this method is still insufficiently w9rked /- out. Some methods were suwested by D. E. SHCifegolev and other authors, and what it came to is that "mechanical" syrchronization was replaced by "mathematical" synchronization, Log., the special methds in the reduction of observations were not implemented quite simultaneously, but were related to a commn scale of time- stardard tIme of the USSR. With the participation of the geo- clesical service, exneditional stations and many o*.)servatoriesof the USSR and socialist countries, the carrying out of a methcd 141

of cdctrfan@atiorr mas done on the space i”lC0r the Kiril Tslanda to East Gemany with a general extent of over 10.000 ka. Traditions instilled by the founder8 of the observatory centime in the area of geodesy. 142

"HIOH UTTERS" ANl EVSR'IDAY WORK

The opinion has been excressed that; astroncmers OCCU:?~ themselves only with "high matters-" Uxdc?abtadly, astroncmy is ar. ideological science; it to a significant extent is con- \ meted with phil~soo!!~,in partic.ilar with dialectic material-

i8me But before that, to indulge ir. philoa.rphical reflections, it icnecemkry to create a firm basis for them, otherwise they c-vl be shown to be erroaems. Already from previ-us ci apters it is evident that astronomy is alsc closely cmnected with practical activity of pecpler for examole, accurate time and coordinates are equally necessary for the orientation both on the sky and on Earth, procured as a result of "celestial ob- serPations'lproduced on the Earth. Wore often of all this role of qround arrtroncmy remains unnotlced, acd its importance is spoker, of, althouerh it would seem that half of the scientists an? scientific departments of Pulkova Observatsrjr give principal attent;lon Dricisely to it. The other half (astroohysicists, radihytrororners, rather than stellar astxrcmers) is more closely contizuaus to "high matters," as far as it is connected with observations of astronomical phencmena and it is possible to say "performs discoveries." Howwer, to "discover a new star," or "c3un+ stars on the sky," to measure the distances to them, to broader the frontiers of the surveyed universe, to discourse about the gcinm-on of the world, is not at all a simnle matter. In order to discover 143

something new in a8trOnOakye as in any other area of accurate knowledge, one eenerally has to beair. with a creation of apparatus. Of course, modern telescopes are constructed and manufactured chiefly by factories, but not without the particlpa- tion of astronomers, who still “nurture the idea“ to the expression of the thought concerning the construction of new equipment end work out the method. Then. after the realization of the idea, a thorotgh investhation of the instrument and the improve- renTs of nethod, Trolonged observations and the processing, laboy-consumjrg to them. falls to the share of astronomers. The division of labor was a ratural phenornencn. Collective investisations were especially fruitful, but in the collective not everyone has to collide with a “high matter.” iievertheless, an astron-mer looks on it like on a workhg topic, without shy- nessr in exactly the same way as a worker of any other profession considers a tonic of his activity. Let us return to photographic astrometry. Laying the foun- L dation of this area of science, S. K. Kostinskii aetermined its program for Pulkovo more tha.1 decades ahecld. A disciDle and a

LI successor of Kostinskii, A. N. Deich compieted in 1942, and in 1947 published, a discussion of a catalog of prDper moticns of 18,000 stars. Besides an ordinary (for such investigations) deterrninat:on of the direction (aDex) a:-d velocity of motion of

L the Sun in 5pace, A. N. Deich deduced the so-called secular parallaxes of various grouns of stars, which allowed the distances to ther, their true luminos;ty, and the total absorption of light 144

which war 8uggm~tedby the American a8tron-r 0. Euiper, who almo diecov8red them and earlier publirhed a uhort note himuelf. Accordi- to identical proper aotion8, A. K. Ddch revealed a aignificurt quantity of double 8- and discovered that, of mry 33 8tcrs. one turned out to b double. The question ia co~eornmtho ddely separated star8 not obmerred visually in the form of double@. but preuenting thenm~lVe8afi physim&lly cotinected pdra, or wide stellar pair8.l

lme newst stars 30 the sunD AX- and ~roxiraCentauri, are an example of a wide stellar pair. The firot- Alpha- is itself a visual double with a distance of l?%between the coa- ponents ad a total luminosity of alaoet 0 magnitude. The second- Proxima- ie a star of 11th ma@iitude, displaced from the bright pair by an angular distance of 2O 11' . It was discovered in 1915 by R. Innes (18614933), the director of the obrrervatory of Johannesburg (South Africa), on the basis of the total magnitude and direction of proper motion. A oubsequent aeasu-ement of the parall= of Proxiu confirmed the presence of the physical can- nection of it (through gravity) to Alpha Centauri. After the discovery by Innes, Koetinskir put together 8 special program of photowaphiw bri,ght stars and their surroundings with the aim of revealing wide stellar pairs. J J The "first epoch" plates of Belopol'skii and Kostinskii now acquirad a greater value. With the establishment of the

normal astrograph in the postwar period, 8 second series of plates came to be obtained with a difference of epochs of 50-70 years with regard to the first series. The ricbest material for the Cetermination of stellar proper motims was obtained, and the study of the motion inside star clusters and gaseous nebulae (accordine: to the ill-minated *r?odules* on -I pnotwraphs of these remote objects). Only in the postwar years were prooer motions of several tens of thousands of stars determined, the determinations being distingaished by a high -. orecis;on thanks to the gre difference of epochs. An exten-

W sive investigation was carried out by V. V. Lavdovskii. The, prooer motions of 13 orJen star clusters and the stdrs in the'r environs were studied by him3 over 14,200 stars were measured. Data of modern three-color colorimetry of stars was drawn to

the inveatieation. As a result, not only the pecQliarities of the motions were studied, the measure of the clusters and +,he

quantity of stars in them made more accurate, hut the cDmposi-

tjon of the "stellar pnpulation" of the clusters was alst, revealed. The study of the prcper motions of glqbular c!.usters was indertaken by N. V. Gamaler (1914-1954) . Globulflr star clusters are the most remote objects of our gal-lxy, and their prc;-er motions (angular disnlAcements on the fIrmameni), in spite of the relative!) large space velocities, are very small; none the less the res-dt was 3nown by Gamala7 that with a larp difference 146

of enochs such measurements make sense. Z. I. Kadla success- J fu1l.y continued the wmk. A grsun of students of A. PI. Deich 0 0 (C. V. Akhundova, N. M. Bronnikova, L. V. ZHukov, L. S. Koro- leva, A. A. Latypov, A. B. Onegka, 0. K. Orlova) OCCUD~S:~

themselves with a determination n: the prop? motions of various objects, includirw, for example, such khiners as stellar associaticns, ah& wtary nebulae, for which exp-ion is chsracterist ic . The investigaticn of the star 61 Cygni was especially interesting on methodological and ideological grounds. The ohotograohing of this double star, possessirg a rapid proper motion, was begun at Pulkovo by means of the normal astrograph at the end of the XIX century. Thanks to the perturbations in the motion of a component of 61 Cygni, a dark, invisible corn’- banion of it was suspected. Only in 1943 did the American astronmer K. Strand manaqe to calculate the perturbing mass of this c inion, which was shwn to equal 0.016 solar mapses. Strand had available a comoaratively small number of observations, zr~dat F.11kovo material was accumulated over 60 yedrs. v A. P!?pe+.ch cal3ed OUL the reductio; ard analysis of all mrterial rz~dccnfirmed the existence of the invisible companion from ;?e (just from the brighter) of the components of 61 Cypvi w:’th a mass of 0.012 solar inasses and +. period of revolution nf

4.P years, As far F?S the mash of the companion of 61 Cygni only exceeds the mass i’ JuPiter by a factor of 11, it cirn k* regarded as a planet-like body. In this way t!-;e Dossib;Lity of the exis- ttnce of athcr Dlar.etary system was dencnstr~~ted.In acderr: tIFes the prcseccs of o'tanet-like bodies is establish& or susoectsd for at least a dozen stsrs. Cbservations with the nwmal astrqgyaph cintkue. Anqther Dh-tp=a?nic instrment- the 26-inch refractTr- has a siailaz x-zra!. By means of it osen star clusters, stellar assxia-

:nclirfes the 4etermTnption of trigon-astric parallaxes cf stars a?d the chotDzraphina of dmble stars rith the aim crf a study' of tho elements CL their or3itr. The instrument was iinprmed-; the aut-matioz of the observations took rmt: this hapnexd with the dircct particiaation of the observers I. I. Kamev, A. A. -? Kloelov, a?c! 3. A. ?libgin. Their xmos prn3zbly will be rmea- hered thrweh Rany decades, s~cht3at with eratitxie the:: are piintar Y called the A chst Jers od the normal astrozraph.

Also, it ir 3iffkult tr? Imagine F-3lkovo aftar fifty ysars, st'17 amrzst i .s':r.;me?ts of the future there still will be szch

.-2 rc?.a i c * te i .: :.ss as the 26-inch rcfractcr, the attltgdzs 148

of stellar orober motions. OE the baeis of extemive material J 4 h A. lu. Deich, V. V. Lavdovskii, and N. V. FatFhikhin put t-ether a cataloe of 1500 galaxias in 157 areas 2O X 2' (the field of

the n-rmal astruqaph) from the North Pole to -5O declination; of them 600 galaxies were show2 to be suitable for accurate astrometrical measuremects. The accumulatiar? sf plates "of the Cirsf-epoch' was coaoleted ir. ipw (in all 900 plates obtair?d)i

for nlates of the second epoch of t+, it is ?nssible, it i3 still to be done: the more the decades pass, the greater the accuracy of the subsequent measurements. However, it was of interest to obtain them for the observers themselves althrum it would be a orelidnary result. Therefore, the rqpeated DhntoCTaphing of the same areas ad the joint aeasurement of 'he nlates of the first and second encrchs has alrc :dy beeun.

fi Works acq9lred not only an all-union (Wos?or, Kiev, Tashkent), but an international. character (Bucharest. Bordeaux, Tou13use,

San Fernando, Sharughai, and also chsc-rv, 'lories iE the Southarfi hemisphere: Santiago, Perth, Cape, LaPlata a& CordcSa) With the establishment of the new astrocfraph in Chile Pulkovo Cbser- vatory obtained factual material over the entire sky. The other part of that fzrandiose work was the observation of minor olanets fQr the orientation ef the system of coordinates. A large erraup of observers systematically proauced ckqtoeranhs of selected mircr plar.. cs wLth thc normal astrcgraph at Pulkovo (since 1949) and the zcnal astrozraoh at Nikolaev (shce 1961):

the results of the observations are oublished iR the form of precise coordinates of the planets in Soviet ami international circulars. The participatCon cf observatories of the Southern hemisphere is also assumed in this uork. At restored Pulkovo photographic observations of the outer olanets of the solsr sysker- Uranus. kptune, and Pluto- were re~aed. In connection with the development of cosrormutics and the necess:ty of a more precise deterrination of the orbits of tbd large olanets. atteents were ade for the detemination -ofthe ccrordinates of the bright olanets (Vems aal Mars) with a &otcr#.-aohic method. wnich before mve results essectially lower in precision than meridian observations. The special method, apqlied by T. P. Kiseleva for the observati0.m of Kars. Drduced the desired results the accuracy wcs shown to be ev!?: sxaewhat h;qher, in comparison 6th meridian observations. Astraohotwaphic observations and measurements were utilized, for exwnle, for siich orcrblers as the deqision of the question about the asymmetry of the discs of the planets A Juoiter and Saturn (KH. I. Potter and E. N. Strugatr\skii>. which eve, however, a nemtive answer, in spite of the assumoticns of 19. A. Kozyrev cmcerning the 2symmetry of the fcrm of the northern and souther-. hemisoheres of the rapidly rotating olanets. The study of the form of the Earth, on the basis of an analysis rnf the orbits of artificial satellites. aonare:.tly cnnf 'rms tnis a3sumzti on. exoressed low Sefore the apoearance of ASZ'S. Se now cnnsider astr-cmical prcblems in real earnest. The interest for the nearest celestial bodies- the Noon and Dlanets- first weakened, then grew in relation to the development of the means of observations. At the present sment it is hmssible to speak of its slackening, but several works

of Pulkovo astronomers ir! some measure anticipated the advance of the cosmic era. Before all it follows to mention the works

Of Ao V. WkcV (1897-1968) and hfS ~uD(Pi- $0 OrlOVas Eo K- Fs / P Kackjlan, IO. N. CHistiakov and others) on the investimtion of the rhysical characteristics of the lunar surface on the basis of conparetive dtotmetry. polarired ad radiometric measurements, as a ,result of which the deduction about the temperature of separate formations, the raqhness af the relief and the characteristics and aee of lunar rocks were procured or deter- lelned more accurately. These investigations acquired a soeciai slm-ificarrce in combination with the radio lccation of the Moon and radio astronclrical obse-rvations produced at Pulkovo under the direction of N. L. Kaidanovskii. In 1960 an interesting collection, "The Woon," was oublishcd under the direction of A. V. Markov, which enriched methodaloeical questions ami results of grour:d observations. In December of that s7-e year the IAU, imparting a sscial simificance to the achievements of %viet scientists, organized ap. internztional symosium at Pulkovo which was devoted to investietions of the 2 Moon. Of course, the principal tninas ir! the notice of the day

'The ma-erials of this symDosium were oublishei by Pulkcovo were the reprts concerniw the results of the photography of the back side of the Noon by means of the third Soviet interolanetary rocket. which uas :aimched on 4 October 1959 and which later received the name 'Luna-2.' In the decipherinq of the fist ohototzraphs of the surface of the Moon invisible to the k*trs\ EarthAPulkovo astronomers ass- participation (A. A. Nikharlov, a A. V. Markov. I. I. Breido, D. E.-- SHCHegolev). Later on they also oarticioatcLd In the processing of the ohotographs obtained by the space oro3es "Zcnd-3." "Luna-9," and 'Luna-13." almost It seemed as if wound-based astronomy would-have :\ nothing to do in relation to the Moon, especially after flights of pende to the Moon. However, such an ooinion is not quite correct. and the works of the Pulkovo astronomer N. A. Koeyrev proved this. On 3 November 1958, while taking observations at the Crimean Astro&;sical L .servatory by means of the 50-inch reflector, he disc;v;-red a ohennmenm which was interpreted by him as volcanic. Ths search for active processes and changes on the Moon was car?ied aut during all beriods of telesco4c observations, but even in the last century the odnion was established that the Moon was a dead body. Canvinced of the activity of the Moon, Kotyrev persistently soueht an indirect ziznifestation of interior oronenetic forces, in Darticular, igneous gas from the ipterior, %.e emergence @fwhich on the lunar surface cas be observed with

Observatory in Russian under the general editorshio of A. A. Mi?- .ailov.- New things concerning the Moon. Moscow-Lenherad, - -I__ a soectral method. The unique spectroqram obtdned by him precisely testfied to that phenomenon. His interpretation called into question for a duration of ten years. O~ly*ecember of 1969 did the Committee for the Business of Inventions and Dis- coveries of the 6r.c;I of Hinisters of the USSR award N. A. Kozyrev a dinloma for the discovery of lunar volcanism8 and in October of 1970 the International Academy of Astronautics rewhed him their gold medal with imlaflted diamcnds portraying the constellation of Ursa Najor. Es-sntially, N. A. Kogyrev introduced somethire new into the investigation of olanets. For examqle, for the stidy of the chemical comom'tion of the atmosphere of Venus he proposed (1953) to ohserve the spectrum of the luminesce2ce of its dark side, Log., that part of the Cytherian atmosphere which is situated above the clyuds escao'ng from the lower atmosohere and surface of the Dlanet.

In this my he detected nitrogen in its atmosphere, the oresence of which was confirmed with the direct investigations of the interolanetary Drabas "Venera-4*-*Ver:era-7" with the entry of them into the dense atmosphere of this mysterious planet. In accord with the observations of Kozyrev (1954) and his interpre- tation8 the ml:rr caps of Mars to a significant degree present themselves as Etrnosoheric fcrmat;on' (snow clouds). Later on other olanetary exoeriments confirmed this. The articles of Kozyrev, side by side with the results of the observations, contained profound and elegant theoretical dis-

CCIW~LS I withcxt the cumbersome calculations giver. ta original treatments. Thus, he theoretically moved (1963) the possibility of the existence of a rarified hydrogenous atmosphere for Mercury, althowh his obsorvaticns in favor of the proper theory called into question other auttors wno spoke of an atmospher: of carbonic acid. Observations ar& theories of another type, the wrong way around, have stood the tests. The question here is one of the obsemations of the rive of Saturn (1968). Koryrev detected water vapor in their presence and explained t3is as a phenomenon of photasuhlimation- the rwification of a crystal lattice of ice, a fraction of which makes up the rimzs of Saturn, under the action of Dhotons of solar radiati~n.~The work of Kozyrev stood in contradiction to the investigations 3f the American sstronomers C. Kuiper and D. Cruiks.'lank, who interpreted their observations as the mesertce of ammoniac ice in the rims. However, at the beainnina of 1970 these authors rescinded from their previras intermetation and came over to the explanation ccmnletely corresponding with the results of the Pulkovo astronomer. Kozyrev carried out his observations with the use of the ++ * instrumenf'of the Crtmem observatory. Because of the white- nights-- in the summer, partly also b=.cause of the low altitudes of planets above the horizon at times favorable for observations, large tele- :copes were unsuitable to be established at Pulsovo. They are situated in southern states.

'The concent and term "photosublimation" has not been used in ohysics until now. -A Observations in the Crimea alloved A. A. Kaliniak, another Pulkovo astrophysicist, to carry out a highly complex invastiga- tfon of the GaJ;?.saq satellites of Jupiter in search of atmos- ~here8suspected -for theam4 The search was carried out by means of a specially constructed spectrograph in combinaticn with an image converter. In the neighborhood of wavelength 5300 (the visual portion of the spectrum) in the first three satellites, and especially clearly for Ganymede. spectral lines were observed which did not belor! to the Fraunhofer solar spectrum. Their appearance could relate to the calculation of the presence of atmospheres of the observed satellitesr although for a number of reasons a question concerni 3 their atmospheres still remaim to be resolved. The use of insge converters in the capacity of receivers of

'The four bright satellites of Juoiter (Io, Europa, Ganymeder and Callisto) were discovered by Galileo in 1610. Tine dimensions and masses sf three of them (Europa excepted) exceed that cf the Moon. In particularr Ganymede is greater tha? the Yoon by mcre than a factor of two in mass and almost oae and a half times ir, diameter. This circwnstanca and severai others led to the idez concerning the Doss€ble exhtence of atmospheres for them. liKht extedsd the oossibilitiee of telescopes. Thanks to the transformation of a beam of light into a flow of electrons, it is oossible to trammit invisible radiation (for example, infrared ndiation with wavelengths to 1.3 microns), for which ordinary

platesI- are insensitive, into a visible radiating image. The luminescence can be iptensified, dispersing electrons with an electric field, wh'ch even mre so ca~extend the power (aperture) of the telepeone. Esmiklly advantageous is the direct action of el&trms on the film located inside a vacuuni tube, where the 7 electron flow farms. The laboratory headed up-by A. A. Kaliniak worked over this in the course of a num3er of years. As a result of orolonqed experimental sewc-hes the construction of an electron - camera for inter-vacuum pho*os;-=t3m 3as wcrked out, whfch marke3ly differed the camerz oi--3.- i

*With the landing of the America? nrohes Viking 1 and Viking 2 on Mars in the summer of 1976, analogous clata for the Red Planet are also available. (Tr. mte) 159

pressures and different oDtical deoths, i.=., wlth the chanye of the gereral path of light passage in the tube by means of repeated reflections, the number of which has now reached 20, wh'ch signifies a 2 kilometer depth of gas. In oost-war times, thanks to the energetic activity of V. A. Krat, who headed u,?the Pulkovo heliophysicists. a wide ranee of investigations of the Sun was carried outO5 In -;he

%or an understaFding of termindogy connecte' with solar investieations, we are reminded of several terms abcut the Sun. The Su- presents itself as a gaseous sphere with a dianeter of about 1,400,000 kilometers. Being of gas, the substance of the Sun, however, is highly opaque: observers possessed with various means penetrste to a depth in it of not more than 400 km. There- fore, the solar dtsk precisely appears to be sharply outlined. The visual diameter of the Sun amounts to 1920". hence, 1" = 725 km on its surface. The external border of the snhere (about 075) amears snmewhat darker at the edae of the disk because of the fact that the edee rays pass through a significantly greater thickness of eas than the central rays. The luminous surface of the Sun is cslled the ohotos ;here. Its average temnerature is

6000 OK. The Dhotosnhere is heterogeneous; it is comnletely m,tde

UD of luminous spots, spread out like a view of "rice grains" against a dark backmound. This heterogeneity bears the name of oranulation. SunsDots and faculae (long luminoue format?ons) also have to do with the nhoto.;phere. fflgkr than the basic surface years of restoration of the observatory attention was concentrated -P +,he completion of the processiug cf ms.terials from 1936-1941 ad the cbservatisns of sclar $clipsea w:th the help of preserved equi?>rnmt. Except for the ecllpse of 1945, emeditions were 3rer.rizedr to Brazil (1947), to n CI CHi'ili in the Kazakh SSR (1952), in the So;ithern Caucasus and in Kuban' (1954) Several expeditions only partly carried out their nrotr-am. For example, if7 3razi1,

are situated layers (at about 7000 km height) which car. be observed only under special conditions (a,: the times of a srlar eclipse or with the use of spectal apoaratus) and visually apaear like "fiery mass" of red light. which is called the chroriiosilhere. Above it aonear the nrcminences (ejectiqns of material), wliicn reach altitudes of 5O-lOO,OOO km. The ~uterenvelope itsilf is the sylzr cnrnna, h:ivlnfr a radiant texture. Cbservations of prominer.ces and the cnrcna also require sxcial aoxratus. Kww1ed.e about the interior of the Sun is ziven or:ly b-; thevy, hut its concl-usicns led t:?einsi?lves to 2ractical verification. The temperature of the center (ab?ut 20 millior! dameesj result? in thermonuclear reactions, which reprezenl; the s-urce ,:f s-la? energy. The trapsfer of etlergy from the interior to the surface of the Sun ahnqens by means of rAdiation, although the?- retically the existe:,ce of a skin-dee? xone af cc!nvection just unner the chot'snhere hiis beer: .ir?ven. Many authcrs have written that it carries awy the r?h?tcs-,here and granules .,re-:ent ther.- cslves as c:epar:ite "cpnvection elements." 161

because of cloudy weather, it was promsect to carry out only radio astronmy observations. However, the preparation for the exoedition and all of their organization demanded, in any case, much time ad energy. The orocessilzp of materials of observatiens obtained at fl ?ulkovo until the war, and in Tashkent during the e,led to the snellinq out af a seyiea of articles an the investigation of sunsmts and faculae (T. V. Krat), prominences and fil-nts 6 (V. 5. Kugherova). and luminous flocculi (V. Ne tuckov). - 6Pilame-.ts are oromfnences projected on the solar disk which are o3served under definite conditions in a3sorption (as dark for- naations); at the edge of the sclar disk prminences are observed in emission (as lultinoua formaticm~. Flocculi are extensive 1un:nous formations in the chrom-snhere. sometimes called chromo- s-he-ic faculae, but which are observed in mon-chromatic light,

far exan!-le in the lines 3f ionized calcium and hydroper.. then. as Dhotas-heric fac'rllae. are visiSle in general (inteerat -") light. Ph-tomranhs of the sclar surfdce, obtainea in nor,-chrcr .*. 'c litz3T, are csllo; soectrnhel:oerarns. Filaments and flocculi appear xi orcc!caly such photc?ra:>hs. Of ccurse, a spectrcheliohram shaws :he fea+ur&-sof the distrrbution mer the disk .?f the Sun of that ckmiczl elenlent in the rays of which it is taken, on accnunL of whictt s-lar formaticns tneinselves obtain the names of calcium ar hydroae-,lc fi.>ct?lJli or filaments 162

Obsemtfons of eclipses were utilired for the study of the n ch?craasohere atxl cor-na. V. P. Viluani& (1908-1960) carried cut a thoro- investigatioh cf the chromosdm-e from rateride of the eclipses of 1941, 1945, and 1952, obtained with the large prism camera with the phctosrraDhing of so-called solar flares (the the moments of the interior cmtacts of the lunsr ad sclar disks durinig total so:,.s ecliwes).t These were smtra of the

7@'Flaresmnear the second ernd third contacts of as eclip8e cmsist of the sudden transfamatian of the dark Raunhofer lhes (whfch characterize absorption) into brlght emission lines. The layer %nwhich such a tranrformation rakes crlpce was earlier cal-led the 'reversirgt layer@':accordtne to modorr notions, there is RO Intermediate layer wnatevep between the photosphere and the chromosDhere, rather, the reversing of the lines takes dace orinciDally in the lower chromosphere. The term "flare" (for an ecliose) must be distiqruished frnr! a similar, outwardly sclretimes identical term, @'chronrrs;hericout- burst&@' or sim-ly @'outbursts.@'CR-oaospLeric outbursts (in populc. literature they are often called "explosions on the Sun") can be bicked out on SDectrohelioarams taken ir. the line of hydrceren H* as the brlghtest formations on the Sun watch do not exist for a w-lollr'ed Derrod. Tney are observed by means of scectrohelio- scooes or soectral telsscooes, which are furnisned with an interferometric-polarizing filter (IPF), intended for the oassafce of monpchr-matic lfcrht (in a narrow wavelellrtth range) in the linc? of H$. most external layers of the solar atmosphere. basically the chruJlas&eta. All material was investigated wit: pnrticular thoroughness and Pulkwo-style ~01~8~ientio~88.which allowed valuable data concernim the aysical conditions in tne chroao- sqhere to be extracted. This very material was used for a U ssctrophotoaetric investigation of ordnences (V. H. guiltor) and for the dotometry of the green lb?of the solar coro~

(T. V. Wt). rhich resulted h the diSCOWr) Of IO-tiOnS in lower narts of the corcna. later on calld ocoronal condensations."

In the observatfons of the eclipse of 1952 V. 2.. Krat utilized t slitlcss meniscus diffraction-prism s*ctro!rk=aoh of his own desim d carried out absolute soectroelotznetry of the chroao- s-he~e. The chotoaetry of the solar c~rona,according tc direct olates of it at the time of the eclipses of 1s5 and 1952, was

h carried cut by A. V. Markov and N. No #iKhefsmi, for which a smcial isorhatometer w.s cmstructed for this nurpose. In 1948 /-, N. F. Kiiorevfch constructed an instrument for the autcmatic re@- strafim of the orofiles of the lines in the sol= sceztrum- a chotaelectric soectrophotarneter. which orgduced a record in "in- tenslties." This was significantly mere advantagems than the measuremect of scectra on photorraThs, which registered "darkenings" and not "intensities," which directly charzcterize a quar.tity of e-ertry: for the tranfcmstion of the darkenines intc, intensitias labor-consyJming work is required with the utilization of the characteristic curves (calibrations), which at first are 2ecessary tc be formed wrth the calc-ilatior. of their individualities for svery 164

n phntoerahic elate. Ruch later an imprwed 3adel of Kuwevich*s soe~troph~tometerbs been regularly used to the oresent time. A great amount of material uas collected by T. E. Dervis, L. h'. auk-, and L. A. litrofamva, ccvering one and a hirlf cycles a? solar activity. In their pblication in 1960 a change of the central intensity at several lines rith the phase of solar activity was natedt the higher the Wolf number, the lower the cen*d intensity. This result gave rise to doubts (no changes whatever in the sbectnn of the Sun hA previously been okserved), yet American astrnncMerm did not confirm it in 1969. A nunber of theeretical-expertrental and theoretical frrvesti- Pations was carried aut in the first post-war years. 0. A. Yelo- n;kov redetemined the ten-erature of the reversinq layer. Accord- €ne; to laboratory intensities of lime of iarised ircc, i. A. Yit- rafmova made a 'curve of yrawth' for the Sun- a praphical recre- sentation of the deoendence of 'eqxivalent isidths" of spesti-al lilies

OI? the maker of absorbing atoms. V. A. Xrat published severzl articles on general s-lm circlllations, questions of iRterpretation of spectrohelioerams, the deve1opme.t of the forms of fomticns in the sclar atmosphere resqlting fr-m a princiole formulated by him, "elec+rostatic stationariness' in the photos?here and . .romo- 8 8-here, the ccns+ancy of elecrric fields in the plasma. These

*A plasma is the "fourth state of matter" (srlid, lio_uid, and pas excooted), a hiphly ionizze gas, in which ycsitive a&. nepative charges, which are created by electrlcully chhrged sarticles (icns works were the theoretical basis for subsequent investiptions. In the 8~-r of 1950 I. A. Prokof'eva established a am11 telescope rith an interference-polariring filter (IPP) in L'e -naval tower" (see p. 19), which was designed ard mewfactured by Si. Bo Ioffe. This telescope was the first model of a standard instrument. the chroros3heric telescwe 'taken tc 8~1s"by the solar services at the beginning of the ICY. Observatioris with m IPF rere later oroduced in the Caae of the horitontal solar telescope; the material obtained was used for a study of

chraaaosbheric hete-mity i1l1(i served as one of the sthuli for the creation of a theory of the heterogeneous chroaos-here. Obsemtions of the Sun extended in different directions with the Fcanstruction of tire horkmtal solar telescoce in the sprina of 19518 direct ohctography at the prime and secondary f-wi (with focal distames of 17 and 60 meters and solar diameters of 16 and 56 cm. respectively). spectral observattons ky means of quartz (orism) and diffracfion spectroaraehs, the automatic registering of solar spectra, and the chromosgheric observations with an I?P. Observations of the Sun allowed the features of ths Pulkovo astrbclimte arid its advantages for the perfonmiice of delicate investigations to be determined The a6 a mild and dam3 marine climbte *the relatively law heat of the and electrons), are idectical or almost idextical in any vo!ume consitered. The aubstance of the Sun and s%ars actually is not a gas, but rather, i.3 a plasma. soil in 8-r days create favorable cr.ditfon8 for daytime observatians. Often the %ashed antm imge8 do not exceed several tens of seconds of mr and sometimes it is close to 012, the limit of resolving power which the rtmoschere generally allows at the given altitude above sea level. Obaarrations were intensi-iy continued till the surer a? 199, when the wooden dome burned dmn due to defective electrical wiring. Obsem- tians were only ~osmcdin the autumr? of 1955 in a nerly constructed dome of "fireproof" construction. The series of oictures of s~largranulation were an imor- tant result of tne first =rid of observations (1951-195b). w If Ganskii succeeded to fix granules wfth a visual dr:i.meter of abcut la, then on the new pictures granules were discovered which were tuice as snalb in size (to 038). This led V. A. Krat to the sug~estionthat still smaller gramales exist: and the ohserved sizes would be characterized hy only the resalvlwg ooner of the instrument (j>ifi-.ly with the atmosohere). Although the thoueht was not taken as a orediction, it came true. In 1957-1959 the American astronomer K. Schwartschild obtained ex- ceotional pictures of eranulation. according to clarity, with the ascension of a telescooe into the stratosohere, and confirmed the or?,gresis of V. A. Krat. In 1966-1970 Swiet stratosphertc solx stations sumlied oictures on which the smallest qranules di3 not exceed 100-150 km (less than 0:2) in diameter. The confirmation of the oroenosis led to results af great sianificance. In 1954 V. A. Krat main set down the hypothesi8 concern- the wave nature of granulation desoite the ridesoread corwiction that granules present theaselves as convective elements. The hybothe8h was converted Into theory. Indeed. if there were no starxlani elements, if mules of vanishingly small sixes were encountered, then the phenomenon of granulation was irdeed similar to waves in the ocean, where the brieht places were the crests, and the darker spaces re6 the places between the waves. The ideas of V. A. mat concerning the wave nature of the phenmtena of the solar photos@he&d:-penetrated aaany investigations of Pul- kovo heliaphysicists, who advanced like a si@e front against this mystery. A pcrwerful diffraction spectrograph was established in 1956 in the new dcnae of the solar teiescora. Constructive ideas of the d ’capable youw scientist, V. N. Karpinskii, were used in its construction. The new swctrograr?h granted o”servers wide pcssi- bilities. Investigations of the chromzsphere, prominences, ar.d chromosoheric out5ursts ccnt’nued w.th entnusiasm. CinematoWaGhy was apolied to the study of eranulation by M. Kerimbekov; the “duration of life” of Praxles cnnfirmed an zlready expressed point of view on their nature. The photcelectric observations > of Yo A. Krat and I. V. IUdina bore witness to this very fact. The practical im-.ossibility of measwine the horizontal motions of granules (in the pictorial plane on the surface of the Sun) created difficulties. But these difficulties were overcme with the olaclnff into oparatiofi of the oriRina1 autcmatic mametograph n of L. M. Kotliar (1959). The magnetograph allowea the intensity 168

of the magnetic field (the longiti#iinal. component) and the radial velocities to be siinultaneously recorded; after improvements on the iiistmnrent (1963) it again beeare possible to register the brightness of -:& measured strip, which 1s equivalent to the heliagraphical "binding" of it to sunspots and chrarosl.lneric foraatima (flocc.Jli, filements). The first works A 0 -0 of 0. IA. VaSil'eva and C. F. Bi~shinwith the use of the mag- netomph led to results deserving attention. The observations obviously could be interpreted in favor of the existence in the ohot3aQhere of phenomena which resemble sound (transverse) waves and q-ity waves (longitudinal oscillations resembling the agio tati-1 fn a water elass in which a stone is dropped). Superpori- tinn (interference) of these waves gives the observed picture. "Thus, the ghotosphere of the Sun is this cantinuously churning ocean of gas," as sumariees the referred-to wcrks of the authw of the theory himself. Another direction of wark wCis the development of %ne ideas n of the Pulkovo astrophysicist E. IA. Perepelkin (1906-1937) can- cernlno: the heterogeneity of the chromosphere. Although the first observers (in the middle of the XIX century) compared the chromos-here with a "fiery Drairie," emohasizing its heterogeneity, they theoretically considered it to be a unfform layer in which the "5arometric formula* or a lsw similar to it operates. Pere- oe?kin was the first to try to burld a theory with the consideratinn of the fact that "the chromosphere appears like a gtthering of a l?xe number of separate filaments- prominences," which only 169

btause oi tbir mat nmtmc statistically +am a cintinuous - a”&ll at first glanee.a This representation #LB obtained in the-

duvelomnt works Vm Am I[rat, Vm Krat, - 8tatx&+nt In .-the - of T. and Ym Mm -$oboIev on the mi8 of modern knouldge about m- characterhtics of 01-m !he chromephere is consi&md to be a triuisitional layer. not in eQuilibritm. frm-the photoenhere to- the corowi) it-consists-of currents of gas moving upward dad in the magnetsc field, wh5ch 3s muouitd* ir.to the plasma and forms with it a siagle, whole entity, because of which the chromosphere is prssented as being in quasi-equilibrium-. Its discreuancy consists of ?his, its mdialecticmoWhat is more,- 8s far as the exr?ansion and pressure of the gas (with the ascend- ing and descending streams) in the magnetic field results in strrmq oscillatims of temperature, a difference of temperaturs can be observed ir, the chromcrsnhere (in that very same lhjer) at the determined mments of time: therefore, lines of srch atzms and ions can exist in the spectrum of the chromcs3here, the spectral indications of which appear in non-identical yhysical conditions. The theory of the chromosphere in non-equilibrium was not only worked out quanitatively, it was led there for the calculation of numerical values of different parameters in their compar€son with observed data. 4 A significant quantity of work (v. N. Zuykov, M. N. Stoian- ova and others) was devote3 to the analysis of epectra of flares n and wominences. In 1958 V. A. kat and Lm N. Pravdiuk observed bands of continuous emfssion (a Srieht glow), the source of whhh ia p1aiced in the photosphere.- The phenaremn resembled chromo- ssric mthrsts. however. the outbursts were in the photosphere. Heme, the- @&?reme was suggested that outbursts can arise in both layer8 of the Solar atmosphere. The preseme in the facu- lated areas of the dissemination of hot gas with a temperature of about 5010000 was established by the same authors according to obeervatians of the lines of helium such formations are called ahat 8mtsea In 2956 T. V. &at detected previously unknown formations in the zhroaosphere in the form of dense clots. resemblirqg deme orminencee- achromoapherfc condensations. a %'-$hirtJ direction of work was the solar service. On the unQlg %hem works were ccncentrated at the Mountain Station of the ~c~&d~IAstronomical -9..Systematic observations at Prrl- kovo have been conducted since 1957 in connection with the ICY, they beiw organiaed at once with observations of the magnetic fields of sunspots according to a method worked out by C. F. Vk*?hin. A year earlier the corcnoeraph of I. A. Prokof'eva bean ta work at Pulkovo, which was mamfactured in the optical- mechanical workshops of the obse-rvatory (to the inclusion of the diffraction arating spectromaph) and which was markedly different than the Lyot coronograph, the essential details of which (the "artificial W00n.~ Dlaying that rnle which the Moon does during a tntal eclipse, and the "field lens." also connected with its objective) were absent in the coronograph of Prokof'eva. The imsrze of the Sun was formed directly by the curved slit of the srmctramaDh, which fulfilled the role of the "Moon." In other resbec+s,-care was taken concerniw the elimination of scattered liaht inside the -instrument. Since the time of its establishment, the new coronagranh, much simder in design, allowed photoeraphy of the meen and red lines of the solar corona to be carried out. The observations were regularly conducted, practically at sea level (toeethpr with the tawer,. the height of the installation was about 90 meters above sea level), which by itself testified to prozress. These observations were not included in the solar service, but the coronagraph was successfully utilized for the study of the charac- terfstics of coronal lines, weak spectral lines of DrcnniFences ana chrmasoheric out3ursts. In particular, cormal ccndensations, which T. V. Krat first detected in 1949, were investigated in de- ta!l by I. A. Prokof'eva. The publication of the monthly bulletin "Solnechwe dame"

U (edited by IU. I. Vitinskii), in which, besides weent data of the services of the USSR and socialist cauntries, short scientific renorts are published. has a direct relation to the solar service. TI3 bvlletin has been published since 1954 by Pulkovo Observatsry jointly with the Commission for the Investigation of the Sun of the Astron2mical Council of the Academy of Sciences of the USSR. Amendices to the bulletin have apneared every half month since 196.2: detailed maps of the magnetic fields of sunspots are circu- lated to observatories and interested participants in the form of a seDaratc brochure. Pulkovo continues the publicati-n of the "CataloPs of Solar Activity."

A fnurth diraction of work w.-I? the creation of new instruments. Concerning many works of this genre, we hwe bsth already spoken in general ard in connection with solar irnrestigations, but atten- tfo)'lcl ust once more be turned to them, Bs these works undoubtedly have to do with a number of important achievements of the observatory, which stimulated all its subsequent observational and investieational activity. In 1967 one more solar telescooe was n out into operation at Pulkovo, the ATSV-5 (diameter of the coelostat mirror, the supolemertary and main mirrors D = 440 m, the focal distance of the main mirror f = 1750 cm, the secondary focus of 60 meters, the path of rays horieontal), placed in a special stone rcmm 2ot far from which was situzted a separate laboratory location, but which was cmnected with it by communications. The telescooe was supnlied with a four-chamber isothermal diffraction SDectrograDh of-high resolving Dower, the desipn of which was PrhciQS t eta: wrv a)o t worked out at the n . Astronomical. - n .<- the spectroqrq-ph was cmstructed acd built by the staff of the observatory. In accord with the name rf the apnaratus, four portions of the spectrum can be simultaneously 3hotoeraphed. A. second feature of it cwsists of "scanningn the solar surface. The image of the Sun from me edge of the disk to the other passes over the slit of the soectroeraph, which cuts sut a nortion of the surface (with a size up to 45" X 180"). The photopraphhg of spectra is auto- matically carried out over different swns of time. In such a way the soectroqraph gives infornation of the physical conditions of the determined repion of the solar atmosohere in three measurements: the slit cuts out an area, and the picture of the phenomena according to heisht is determined by the instrument in one or another portion of the spectrm. A spectrum ottcined with high dispersion contains abundant information about the magnetic field, radial velocities, relative intensities in the soectral lines and the *continuous backmwnd," from which the reductions and calculatCons infer diverse physical characteristics.

d 8- m The creatior! by V'. N. Karpinskii and N. I. Pechinskafa of a dauble Giffraction spectrog-caph wi.th digital read-out in 1969 was another achievement in this realm. Works on the construction of a Dhotoelectric monochromator for the double diffraction instrument were begun by Karpinski; at the enc! of the 1950's; the first results were nublished in 1961-1963. The new instrument alhWed *ghosts" (imaginary spectral lines peculiar tc diffraction gratings) and scattered light in the spectrograph to be wactically completely eliminated. Thanks to tkis, contours of the Fraunh2fer lines were obtained in clear view, which, undoubtedly, promoted the study of weak soectral lines which make UD the bwis c?f the sa-lars?ectrum. The subsequent imqrovement of the instrument in cornbinat;on with a calculatnry-decldinE mechanism led to the creation of a completely oris! nal scectrophctometer . On a princinally different basis, with the use of image n converters, A. A. Kaliniak develooed a d.ifferentia1 method of determininq soectral distinctions in the photos?here. His method was applied to the expcsure of ve;r; faint Fraunhofer lines and to the study of all sorts of soace-time variation- on the Sun and in the solar snectrum. The striving towards mlti- reqularity of informat€on led to the realization of a model of a two-chamber coronaqraDh (on the basis of the coronaeaph of Prokof'eva), which allowed synchronised observations of the solar corona to be produced in two wavelenqtihs with an arbitrarj' time scan between them* For monochromatic observation3 of the surface of the Sun A. V. Merkulov worked out a scheme and constructed a model of rl "static soectroheliograph." Especially imgortant was the participation of Pulkovo astronomers and inventors in the creation of stratospheric astronomical stations and their out- fitting, intended for direct pictures of tbe Sun (granulation) and the photographing of solar spectra (ultraviolet and visible spectra &-the central and edge portions of the Sun+ corresponding to the photosphere and chr~mosphere). fifth direction of work was radio astronomical. observations. Investigations of the Sun with the use of radio telescopes were carried out at the time of eclipses (partial, total, and annular) on site {at Pulkovo with the CPR) and with the departxe of expeditions to regicns of eclipses. Attention was concentrated on the study of bursts of sc.lar radio radiation, which hapnen at the beeinnink. of chromqsnheric outbursts, and local sourcesr which e.: iifferently called "radinsi~ots." The study of the latter i:1 especially favorable at the time of eclipses since, with thc hiding of them by the lunar disk (then with the emersion) on@ can con- fidentiy determine (localize) their locations ~n +he disk of ti 3 Sun and compare them with objects Jbserved optic...ly. Such a method increases the possib:lit*Ciof small r2dio telescopes. Tho /qqC Zulk-vc radiotelescnDe, pnssessine a siqnif icant resclvinp rowerr allows observat:ons and the localitaticn af 3curces to be carried out at any time (outside eclipses. but durinp the passage c.f the Sun thr-i@ +he meridfan- the directional ;ayc~: of the essectally at the time of the ICY for the organia,tinn of sinul-

&Lz-e-~s c5servatieFs of chrenospheric @:itburstsand bursts of radio radistirn with ootical and radio astrxw--:a1 methds. 93th methc2s eive similar results fo? the deteminatim of the

p? the idert_f!cation of local sources. Thus, accorc?ir.g to data r of 1'. S. Ikhse -xa, radiosoots often do not coincide w?tR sunsgots. As a result oA diverse observa +ions, thaoretical estimates

PY? :srve-r discussims, Pulkovc radio astronmers (e. 9. Gel-- r -. 0 fTeiFh, V. N. Ikhsanova, N. S. Scbrleva,A.P. Hoichanov and others)

*Cnr?StruCt2i :. n-uel" of local sourres in the form of condensa- tims of corcra! pas, d5scosed above the photcsqhere to a height out that zones of exceotionally high heating can arise above the visible flares. Pulkovo radio astronomers were the first to note this. The mechanism of formation was obvious, with the stmrqz heating, portions of the coranal gas acquire velocities on the arder of 1000 km/sec. which exceeds the velocity of escabe for the Sun (619 Ira/rec). A sixth direction of work mas tht investigation of the nature of solar activity and its manifestation in the solar stern. It ,-I icllorrs !iere to mepticn the works of b. I. Rubashev ani his =cup. At the oresent time it is quit? evident that a convection zone is the main czuse of all active formations on the Sua. Therefore, oraceedine: to a wcrking out of a theoretical method of predictire r relative Wclf numbers, E. M. Rubashev began with a detailed ztudy of the ch-wacteristics of th nvective zone and subphotospheric stratificztion. Having created a theory of the ccnvection tcne as t boundary layer, he found a new methcd of determining the thickness of the convection zone. In principle. the t'F.ickr.ess of it is fixed hy the sites of sunscotsc the lamer they are, the deener they lie. Xmce a rmeh calculating xiethod of oredicticn cam abcit, hawever, it still did not Five the Wolf numbers. T'nes- wcrks ccnt'nue . Ea~irical-st~~tistscalmcthods of DreCicticn of sclar activity were simultanecusly workcd out ar?d im:*r?ved at Pulkovo (A. I. Ol', /- " TV. I. ?'itlrsrf:\. They turned out to be less crude than the cslculatory n!ot.,Od. Preeictions ,If Wolf numbers, made ulj on their basis, uere used by pecnhysicel and r.xdiophyaica1 inst;tudes. A laree quantity of work on the problea of the "Sun-Earth" be- c- lowed to Bo H. Rubashev. In particular, he pro~oseda aethod of calculntion of the heating of the lower ianoachere (with a he'&t of 100 km above the terrestrial surface) according to the observed characteristics of magnetic storm. As fzr as meteorolnerical phenomena are cormected with the heating of the upuer atmosphere. the method. besides other applications of it, was used for the elucidation of the character of the influence P of solar activity on weather. Rubashev showed a direct manifes- tatian of solar activity in the lower layers of the atmosphere (trobosnhere), having established the connecticn of the intra- yearly fluctuations of solar activity with types of atmospheric circulatim. The presence of such a comecti-n helped in the w-rkII1p aut of long-term meteorolcqical predictions on the basis 0 of the oredictiors of Wolf numbers. Finally, Rubashov detected a manifestation of solar activity in the vzriations of briqhtness

of the nlanets Juniter ad Saturn, pericdlcal chanses of Tne zonal rctaticn of Jusiter, etc. 9

Thus, from "high matters." frzm sc?l;ir L ;er ir! its turning hot cmditicns (in the "fcurth state"), together with them, Q

9The examined questians are sarnnari:ed in detail in the litera- n t:m t 9. X. Rubashev. ProSlems of solar activity. Moscow-Ler,infrritd, P .- 1964: IU. I. Vitipskii. Predictions of solar activity. Moscow- Lesinurad, 1963; The_ mroholoEy 02 sclar activity. Lepinerad, 1966. rather fnsimficantly small part of it, having oarted cor- with the Sun in .She farm of a sea of highly agitated charged particles, \.-e mentally return to our Earth. The value Df aci- ence, esnecially natural science, is often measured by its practical applications. Thia was proven in full measme by the exarale of solar investigations. llodern astronomy contains two extensive rezh of inves- tieat€ons especially closely Felated to philosophy. They are cosmogony ami coerp

.??el bel.rnoPd to Linstein himself), whtch, thanks to and only tha-ks to such a orese1itatinn. quest;cns led in e;encr,i to a oic- 180

ture of the ultimate universe in space awl in t€ae, in spite of the historically assenbled representation concernlng the liaitlessness of the universe. The contradiction challenedd many arguaents. At times they flared up and intensified. taking on an ideological color- ing, at tires they subsided but did n3t come to an end. Cos- moeny, breaking into pieces its own object of kzowledge, was the arena of less violent battles, but, in essence, if the limit of the universe were to be proven by cosmclogy, the problem of its origin rszld quickly arise, and this DroSlem would signify cosmnsony in that nrimary and direct meaning of the wo-d, as it is understood in myths concerning the origin of the universe raachinq us from maFy ancient countries (Indians, Egyptians, Jews, Greeks and others). Both prDblems for a lcw time were or,qanized on a scieRtiflc basis. However, the decision of diverse questions of cosmalocr;y and cosmogony in an essential way rlerends on the accunulati-n of facts, observed data. Generalizatians of the achievements of astrophysics, stellar st2tistics and stellar dynamics led to definite conclusions concerning the ale and directims of development of stellar systems of di"ferent classes, several tyoes of stars and other forms of cosmic matter. Here it is sufficient to mention the works of F the oviet astroDhysicist and academician V. A. Ambar?sumian or: tho investimtion of stelhi- associaticns, th ? stability (and d!siqtearatic.n) of stell2.r systems and multiple systems of gal- avies and ether thinzs. His ConcLusim (1947) concernina the 181

fact that *the formation of stars contimes in the gdl- at the present time,. forced the models of the universe to be ir- proved,--accord*.nq to which the birth of galaxies and ;\~drsis computed as occasional and is wmmbiguously connected with an 'act of creatfon.v. The newest achfevements ir. radio astronomy- the discovery of quasar8 (1963) and the backPround radiation (1965) - led to armaments over the use of the ,-o6aal@cal model of an expanding, hot and ovmde.?se untverse fn the past, Now it is possible to n 6 quctte the words of the academician U. B. Zel'dovich: "the theory of the expandinn univw%e is one of the most inportant achievements of science of the M centutyan1 Radio astronomical observations confirmed the predictions of .a. theory that shows a criterion of truth in any theory cr hypothesis (at the borders 2 of its applicability), Born with the theory ,f relativity, it

h B. Zel'dovich aqd I. D. Novikov. Relativistic astrc- phYSiCSa MOSCOW. 1967, pa 307- 2 The theory of +h- * r,g itiiverse dezic ts the Metagalaxy- the supersystem u*\jT : ,'r 3 Fdlaxies- in its ?resent .. state in a Dhas; -. *.r . ?i~i:Iently. was creceeded by a state with - , t .ificantly hiqier tern

0era:ure. Only t.. '-c: L: -.-i ;*adio radiation confirms this anC the calc, :I ; :-. t~ tiensity of '.he distribution of quasars, i! j . L' -aidered, which is highly likely, as a Drsealactic form of ,n!tbc~, Gbservations never say anything 102

alscr demcnstrated the power of its parent. Henceforth, relativistic theary took its stand with a method of cognition of the universe. On this basis arose, and in a very short time developed, a new realm of astronomical science- relativistic astrophysics (or rather, the modern theory of -gravity) in the camcity of a orincia1 element for the decision of astrophysical problems, espec! ~llypi oblems of cosa.=logy and ccsmogmy. However, it does not follow to overstate the all-em3racing meaniw of it. The mathematical apparatus of the modern theory of crravity brilliantly justified itself as the mears of know- led= of the Metagalaxy. It follows ta once again emphasize how telescopes and radio telescooes reached the boun.5aries of this indeed immense supersystem, and how the theory described the scales of it alollp general lines, qualitJtively. Quantita- tive corrections (they were also essential) b,- -nt ir, the results of observation^.^ Observations also allowed a suitable

~~ ~~~ about the fact that the superdense state was primal, cLnsequently, they do not serve as a chnfirmation of the nrimary phases of the state of the un?verse, which the theory calcuiates in detail and affirms. 31n the 1930'~~on the basis of tkeory, the "radius of the universe" was comguted tc, equal 1.8 billim likht years. At that time it was thought that the lOO-ir?ch Mount Wiloon -1sscooe Denatrated to a denth of the univprse to one half of its "theoretical radius." In order to reach its "border" a telescope w;th choice among various theoretical models of the universe to be made. In this way much information concerning the Metagalaxy, in particular, the confirming observations, could be cmsidered as sufficiently proven. This cbnfirms the theory of an expanding universe, althouph on the whole it still is far from being com- eleted. All the more erroneous was the assertion of the advo- cates of the universality of the new theory concerning the fact that it includes the whole universe. It depicts the Met-laxy, and not the universe, and there was no necessity to identify these two different concepts. If the theory led to the conclusion about the limited nature of the universe, then it says, of ccurse, nothing about its weakness concerning the limited nature of the sohere of its applicability. Any physical and mathematical thecry is 3recisely such, because a theory builds on the basis of limited practice and does not allow a limitless extrapolaticn. Only a correct combination of theory with practice (the verifica- twice the size was constructed. Socn it was established that measured distances must be doubled and in this way it turned out that the new 200-inch telescope detected objects (galaxies) at distayces to 4.25 billion liaht years. Naturally, the "theoretical radius" had to 5e adjbsted to tnose things which were observed. Then it once more !nd to change, when objects (quasars) were detected by radio telescones at distances of 9-10 billion light years. tion of themetid co&€tiona of observaticms) and methodology (the theory of -knowledge of dialectical materialism) can lead to -*e- disclosure of ycit unknown mysteries of the infinite universe. Science does net repudiate, and has no basis by which to repudiate the-existeriee of other metagalaxies. - It is possible,

&ere dremdy €8 sore‘set of observ@t%ondl-da&fn‘favor of their .* existence, only we are not able torpsen3ly --a&l of the ------_ able decipher their authentic abundance‘-”l$acts,~_md’.- are bt to meanh;. Thus it ~as. for exaniple, with galaxies. Scientists mndered the existence of Qther galaxies. In the 1840’s A. Hum- boldt expressed thoqkhts on ‘world islandsSa or ‘island universes.’ - as those objects were ca1le.l in the first third of the XX century. Astronomers even made available observational data. As Zar back

RS the end of the XVIII century 3. Herschel cbsemed *unresolvable* nebulae.* among which were galaxies. However. only in 1916-1920 were they deciphered, as a result of which it was prmen that astronomers for a long. time had come into cmtact with extragalactic objects- other galaxies. The accumulation of facts and new. powerful means of observations were required for the proof . Warks of Pulkmo Observatory in a large part related precisely to the accumulaticn of cbservacional facts. Its rde in the decision of cosmoaonical and cosmological oroblelns can be described as modest: the role of any observatwy is such, if a scieqtist does not have to work on theoretical generalisdtions. 4 Howe\rer, at Pulkovo they had and have a dace. As far back as W. Struve. one of the problems of cosmology- the photometrical -=paradox- was daie into contact with and was successfully handled -at that time by them. Later. in 1929, A. A. Belopol'skii attempted to uncover tte non-Doppler explanation of the *red -shiftoNsIn

in the spectra of galaxies tonad the red L 9, which, in accord with the Doppler principle, signifies recession. For galaxies it means literal Nrecessionr* as the velocity of thcir recession is proportional to distance: the fur+'-.e? they are observed to be, the faster they recede. Precisely this law (Hubble's lriw) served as an exDerimenta1 basis for the "idealistic' thiory of the ex- L ?anding universe. Belopcl'skii attempted to give a material explanation of the "reddening" of the light on the basis of the "aginga of quanta, robbing them of energy: quanta traveling in space for hundreds of millions of years lose energy, which is equivalent to an increase of the wavelength of light (a disolace- ment toward the red wavelength side). The exalanaticn of Belo- 4 pol'skii, however, met insurmountable difficulties of Durely 1,hystcal means 186

/- the 1930.8 Pulkovo-astronomers (Be Fa Jerasimovich, A. F. Bogo- J bd rodskii. Y. S. Bigenson and others) enpried out a whole series of worm of a serious theoretical nature. In the past-war year8 V. A. Krat published some quantity of diverse investigations on the questfa- of cosmogony ("On the development of stars," "The origin of the solar systemr" etc.). rf 1953 V. A. I(rat suggested a proper hypothesi8 of the In - oriefn of the solar system which, in his opinionr was formed frm a cloud of solid particles of comet-like tyoe. The Sun itself at the time of formstion of the planetayy system had passed through several stages in its development. The formation of the outer planets took place in that period when the Sun was a hot B-type star with a mass of 5=5 presently sclar haasses. All, material inside the orbit of Jupiter evaporated because of the high temoeramre c+ the Sun. Subsequently, the star (Sun), according to Y. A Krat, underwent . evolution through the Wolf-Rayet, f Cygni and red giant stages. The star passed through these stages (from B .star tb red giant) in 10 million years. 8.8.) "very quickly," according to the age scale of the 9%;~. As stars of Wolf-Rayet and f' Cygni tyce are distfnguished by a cowerful outflow of matter from the surface, that Sun passinp; through the corresponding stages had to have "lost" a fundamental part of its matter, and its mass at the red piant ohase cogld not have exceeded 2.2 times that of the present. The red giant nhase was also not pr longed because of the loss of matter for a different reason (with the large radius escape" of particles was

~ .. ~ . -..+ ~ <'... , of the present. . ~ . . .. A p0.3fti.V~aspect in the hypothesis

-r fact that he was the -fiset 'toattembt tG- possible 'change of the-Sun iTself .dying the period of' formition

0. the planetary system &-in the-,early. period -of its evolution. With thisb the- formation of the planetary system, according to his .nesis, happened mere or less simultaneously with the i process of formatim of the central luminous object. In his ar-' ticles V. A. Krat expressed original understandings as regards the formation and evolution of the galaxy, gaseous-dusty nebulae and stars. A "corpuscular instability" plays an essential role in the develoDmsnt of stars (a principle formulated by him in 19bd), consisting of an accelerated dissipation of the atnosohere of stars Dcssessinp gierant4.c sizta and t. high temperature. Suler- massive hot s+ars,subsequcctly losing mass,quickly undergo evolution. They follow to be related to young objects which formed "not lone ago.'' At the present time such stars are observed only because they still have not succeeded to undergo evalution advsnce their devzhment to cl%Pr&of'-*laterW stars. and-_ in The The a@ of young stars estimated by Ye A. Wa*t was in agreement -n with esthetes of V. A. iiabar&umian, Y. 0. ~use~ovand other

authors QR the basis of different considerations. . As regards works which -re contributing h the accumula- of tiaka of astrophysicd md steUar- tfon ebserya$fons, -. astr,hncmktil invest@k&;ks_.. were of frrtemst for cosmogony. Work on the physics cf nla%eQt.,'-md stellar astronomy were elucidated -in the ~reviauechapter; now the question is one of works on the bhysics of stars. The work of G. A. Wel'nikov attracted great interest In this area. T-- l9U he completed an extensive spectrophotometric inves- tie ion of Cepheids on the basis of observations at Pulkuvo aM Simeie in 1936-1939. Because of the circumstarces of way time, the work was only publfshed in 1950. In several senses O1 A. Mela- L) nikov continued the line of investigations of A. A. Felcpol'skii and I. N. Lehman-5alanovskzia. However, he qave a profound analysis of the physical condltions in ths atmnspheres of CeDheids and a complete oicture of com!.lex nhenomena in them, on the basis of which several inferences of a ccsmogofiical nature could be ma?e. A second Dart of the work contained. a statistical inveetigatioh of lone-r>eri.nJ Ceoheids. The fundamental 13sult of Mel'nikov's imestigatinr, was a more cresise detaninatic of the magpi tude of cosmic absorDtion of iight and the zero-point rf the "period- 6 luminosity" curve. In accord with the new zero-pornt, the ne;?surea distarces in the uoiverse had to be &r-eased by approximately 1.3 tlmes.

It fnllawed tr! increase the linear she of tte Andromeda Nebala *- 'For several classes of-::o-callec physical variable stzirs. fer classical Ce~heids. clnater-tyw variables. etc.. tZsre exists a deoendence, established bk- obstivations. between the period of variab'lity and the brightness, or more precisely, the lunrinosity. -i.8.. wtth the general qua?tity of radiated stellar light. Tharks to this dependence of the period of change of the briehtt.ess, which is cornoaratively easy to observe. it is not difficult to establish ar-! a3solute brilrhtness of a star. But the absolute brightness would bear witness to the true 1min:sity of a star if all stars were situated at an identical distance. As the light of the star decreases pmportimal to the -square of the distance, the observed brierh'ness of a star (the apoarent stellar mqitude), in cmpari- son with its absolute 9,ri~htness. allows the distarxe to the star to be determined. In this way the "period-luminosity" dependence

allows the distance ta variable stars to be determined on the basis of the observed stellar mamitucle and the period of variation of briahtness. This deDendence is also ccnfirmed thecreti- cally. only from c'.servatims it fcllows tc determine the zero- point of the "period-luminosity" curve, but for this it is necessary tc know several initial distances, which often have to be estimated with indirect mnthnds, and besides this, it is necessary to determlnt? the maepitude of the cosmic abs2rption of light. "All intr:c:tcies" of method are c -ntained in this. in the same proportinn, which still more (not only by structure. but also by the actual site) made it shilar to our galaxy. Some time later. in 1952, W. Baade. utilhing results of proper obser- vatfms with the help of the 200-inch Palomar telescope. established that hter@$lac%icdistances had to be doubled, which was agreed by international decree. It is necessary to mention that the determination of the scale of distances, or the zero-point of the 'perisd-luminosity"

CUW~. demm3s on the fact that this hdds for any group of stars as far as they can belong to different "paaulation types." wh'ch can lezd te di4ferent results. 'Cluster-type variables," which, how2ver. are not observed in neigh5oring galaxies, as far as they are very faint, give a more certain result. Therefore, it is

71n 1943 Baride shnwed the diverse make-up of "stellar pcoula- tion." All stars in the galaxy (and other stellar systems) can be suhdivided into two tynesr I- the "population df the planar ccmoonent." which is found in the arms of spiral ~alaxiesand in irrermlar form palaxies; 11- the "population of the s:.herical comoonent," characteristic for the nuclei of ealaxios, 313bular clusters and elliotical qalaxies. The works of Soviet astronmers P- (B. V. Kukarkin, V. A. Ambartsunian and athers) of tha* neriod showed earlier tnat types of "stellar populatim" were mre diverse, and that the affiliation of st:drs to one or anqther type is determined by their "genetlc9"- the cmmunity of "Reneal?gS?al lines." desirable to have reliable scales "graCuated" for different types of ohysical variables. 0. A. Mel'nikov often returned to work on a more r?recise determinatim of the zero-point of the scsle of distances with the calculation of all sorts of circmstances, in particular, the make-up of "stellar pcroula- tion." The works of the astroohysical school of V. A. Krat alld 0. A. Kel'nikov were diverse. On the whde they were carried out 4th the methods of spectrophDtometry and electrozhotmetry. The o3jects of study were stars of different spectral classes, sitwted at different stages of evolution and on different oaths cf develoament. Hichly complex physical characteristics were obtained for stars makine up phot~metricbinkries. Con- cerning the abundance of material, a list, thoueh short, is as follows: soectrophctmetry of the ecliosim variables u iierculis

0- an3 RS Vulpeculae (15. #. Gol'd3erg-Rogozinskaia), an investirfa- tion of hot supereiants in eclinsine: binary systems (A. N. Dadaev),

c electroDh-trmetry of suheiant stars (A. V. Sofroiitsskii), colori- r' metry and snectrnnhot-metry of suhdwarfs (K. Kalchaev, A. X. Derni- cfova). Quantitative analysis of the cmtinuous spectrum and Snec+ral lines (sDectrophotometry)- a more Dmductive methnd of study of the nhysical cmd!tions in the atmospheres Df sinqle stars- was apalied in all cases when the means of observaticns were allowed, in osrticular for the studl/ of "white" and "yellow" suoereiants (T. W. Fofanova), stars in the Coma 3erenices arid Pleiades clusters (N. N. Corokhova), "pseudoce >hei-is"(V. S. Por-c?~), .,' and msmetic-variahle stars (T. N. Kuenetsova). This method uas utilized for the study of the interstellar absorbing medium (N. V. Eystrova). Now it is oossible the time has come to same- how summarize this material, which was o3-i-nined over two ar.d one half decades.

!bo more investicatims were closeiy related to these w?rks. which were connected with the wcrkfne: out of methods, but which were imolemented side by side with observations taken for the verification of the methdst the determination of stellar rariial velocities by means of a direct visior! objective prism (L. A. /--.Panaiotov) and a photometric study of 15 sciral galaxies (I). E. SHCHeeolev). the result of the latter merits special attention. The investitrated Ealaxies have, accordine to the photmetric data, simila- structure: the erimary zart of the radiatim is created by stars of the "sr?he-ical comconent," which fcrms the cmtinuous backzround of the nebula; the sniral arms c-nsist of stays of the "olanar cqmoonent." Absorbine m :terial is ccncentrated in the calactic plane less strcnely than stzrs of the srziral arms, but more strongly than s'zrs of the backeround. Cur g.laxy ?rob ably loqks like that from outside.

The works 5f N. A. Kozyrev stand by themselves, ir which the orchlem of the interaction of cne 3ady (of a mechanical cqm.lex) with ar.nther is stlidied as a nrincipal theme through the change of the 3rqDerties g.\f t'me on accnunt of the znines-sr. in their i-rcversi%le (cause an4 effect) orocessas. Cnly with such an interqcticn, accordinz t? Kozyrev's ooi?i?n, can tne :-hysiczl 193

features of the couipments of dauble stars be exolained, which were discoverqd by him on the basis of a statistical investimtion and which consists of the fzct that that the components of small mass and size seek to cme closOr, according to their means, to the more massive cam~~onents,and %hiais made potice- able because of the deviation from fundamental stellar-statistical regularities, before all from the "spectran-luminosity" diagram. 8

Kozyrev attemoted to investigate the universal orr\nert%esof time, determined in astromnical processes, experimentally and in laboratory cmditions. The appendix to his "causal mechar-ics," inci- dectally speaking, contradicting physical cit*Icns, was highly diverse.9

*The "spectrum-luminosity" dia,warn is one of the fundamental laws of conformity of stellar astronmy and astrophysics. It was first constructed by E. Hertzsprung (Holland, 1911), and some time later, and indenendently from him, by 3. 1:. Russell (USA, 1913), which is why it is aften called the Hertzsprung-Russell diaeran in orevirrus literature . The modern diarrrams are unusually invnlved and are strongly distiwuished from the originals, but OR all, as before, one can orck out the mair. sequence branch of stars, on which the stars of Frehter mass and lurninxity cwresDond to the h~tterstars (stars of the earlier mectral classes). This diagram undnubtedly has a "eenetic" ad evolutimary meanine: for all classes and su~classesof st:rs.

9The nrohlem of the orcperties cf time was set forth by ?ioA- Kozyrw ir! the bnnkt Causal x U-swmetric mechanics & 2% 194

At last, frm the investigations in the area of optical P astronomy, it follows to mentian the work of A. A. Kaliniak, carried c?ut jointly with V. I Krascvskiy and V. B. Nikonov, accardino to oh5togranhy of the aalactir: center in infrared light. The existerce and location of the galactic xucleus was established an the basis of the rotation of the palaxy, +served for stars. Xzwever, such a miehty and comoact stellar cluster at the center, which theory prescribes and which is visible on oh9tosaohs of qther s-iral Sklaxies, we do not visually observe in our mlaxy because of clcuds of absorbing matter (in the constellation of Sagittarius), which obstruct the

-lactic center from US. PhctoeraDhy carried out in l9ri8 with irnase converters at- a wavelaneth of about 1 micron, distinctly show the structure of the galactic nucleus. The yorlng scienqe of radio astrmcmy thrust oper. a new

"wir?dow tc? the universe," which impetuously developed in the years after World Xar I1 and which made at this time impcrtant discoveries of ereat sfgnificance. Before all, radio astronqmy decisively charwed the previous view of the universe as some- thine wh;ch stands its ground, chan-oes extremely slowly,

Qr,.rstp) Cb?rrt/q ,spy linear approximation. The n Astronomical A Lepinmad, 1958, an3 an Zrticle nublfshed in the collection: history -and methndolom of natura? science, v. 11. Physics. Moscow State University, 1963, pp. 92-106. AF. bstrophysical suc -1ement contains more snecial articles. invariable over the extent of billions of years, and is almost unfathomable .in its evolution. Undoubtedly, the disccvery of violent, energetic and short-lived processes has an influence on the success of modern cosmogony and c?sm-log. Not quite so fantastic now, as It was perceived in 1948, seems the thought. A exrressed by V. A. Ambartsumian concerning the possible existeme of "orotostellar bodies," from which the observed stellar asso- ciations are bom by means of an explcsion. Explosions in -~1- axies, far more cowerful than had been supposed, were established by radic? astrommical methcds. The Friedmann-LemaTtre model of the exDanding universe came to be oreferred in place of the stable-equilrbrium cosm?lcgical nodels of the universe. This very model was transformed from the thecry of a one-time forma- into tim of all galaxies aEd stars .A the "bic bars" theory. or the "catastrmhe which ameared at the beairmine: of all catastrophes" in the universe. 9adio astrmomical investigations still have that signifi-

cance for CosrnpIwy.I thanks tc the colossal power of the etlergy sources wfth whfch radio astroncrny deals; they allow the depths of the universe to Se Eenetrated at significantly Ereater distances than optical astror.omy. Truly, quasars (quasi-stellar radio scurces), which allow this to be done, at first were alsr, taken to be the objects (massive superstars) predicted by F. Hoyle and W. Fowler in 1963, precisely on the eve of the discovery of quasars. The disnlacements cf the lines observed for quasars can he internreted not only as casmeloqical (bopo?er-like), but also as gravitatimalr being calculated for collapsing superstars. lo In this case we would be dealing with objects situated comparatively nearby. although beyond the limits of the ealaxyr and which would sooRer be of interest for cosmogony than for cosmclogy. However, there almost remain no doubts nowB that the displacement of the spectral lines for quasars have the Dopcler-like interpretation and that these o3jacts are situated at cosmolocical distances.

"Gravitational collapser understood till now only theoretical€y, is the fall of the mass of a superstar towards i-:s center with the velocity of licht cr Rear the velocity of light, if the radius of the star for some reason is less than the critical gravitational radius for the nhenomenm of collapse. Priccipally, however, a collapsing superstar cannot be observed: it closes not only matter inside its volume (with a radius equal to the mavita tional radius), but also radiation. It c~ri3e prodUCedr but the material inside such a sghere must undergo a degree of corncression such that the eravitational radius for the Sun (or a bgdy Dossessinp its mass) equals 1 kn, and for the Earths 1 cm. The ccrncept cf gravitational radius (sometimes it is called the Schwarzschild radius) was introduced by the German astronomer Karl Schwarzschild (1973-1916), and had made significant theoretical enr;chments in different areas of stellar astronomy and astroDhysics, in Darticular, those which led to the thegry of radiative equilibrium in stellar atmosoheres and which advanced When in 1954 a department of radio astrcnany wxs orgazized 11 at Pulkovo Gbservatory, already over 20 observatories and institutions on the terrestrial glcbe (of which 4 oarticinants w"re from the USSR) had been :,roducing radio astronmical ob- * *& servations. S. E. KHaikin (1901-15168)~a well-known snecialist in the areas of nechanics and radio physics, created'-and headed

UT) the new section of the Princioal Astronomical Gbservatory. Since

n b e 1969 the talented young scientist IU. Ne Pariiskii has directed - '- the section. Still, up to the organization of observations at Pulkovo, naturally, a question arose concert--ing the choice of wrkins wavelenTths at the limits cf the "window of transparemy" fcr radio waves, which was defined by the characteristics cf the terrestrial atmsnhere, which lets in radio mves in a range frm millimeter tc decameter leneths. With this chr?ice was csn- nncted another question- ccrxerning the,nost rational constructim

the first thecry of the interior structure of the Sun and stars - (1905) 11 - At the end of 1969 the- denartmerit of ri.dio astronmy had an influence of the SAfl (Special Astriphysical Cbservat-ry of 1 the Academy of Sciences of the USSR, Zelenchukskaia villase, Ncrthern Caucasus), for the time beim rinair?.in,qat Pulkovo.

Cr?.ly a zrou? of ridio astronamers-heli-cohysicists fiak!ng up the

denartzent of s-,lar Dhys' 1,:s $.vas retained with the ?rirc;.pal

A s t r o n - 7 i (3 a!- C b s e r va t o ry. of radio telescopes. Almost all observational stations worked

then at the most advantapeous meter wavelengths. According to a beries of considerations for the work at Pulkovo a range of centimeter waveleprths was chosen. It to some degree "prede- termined" the construction of the radio telescope, the original P%J 4 decision for which was made by S. k. KHaikin U N. L. Kaidanov- ski?. With the erection of the Pulkovo radio telescope it was sought ta achieve the maximum possible resclving -power (about one minute of arc at the chosen Havelength of 3 cm). The resolution of a radio telescope (reflector), as- for an optical telescope, is proportional to the wavelength and inversely pro- mrtional to its diameter; given both quantities (the resolving power ami the wavelength), the third can be calculated- the size of the reflectors To construct a bowlshaped steerable telescope

(with a diameter OE +he xder of 100 meters) with a high precision Darabolic surface (the flexure cannot exceed 0.5 cm over its whole area) was -not technica2ly possible. Therefore, the construction of a non-steerable fan-tyne antenna was chosen, made up of separate flat elements of sheet duraluminum. On the whsle they ap- Droximate the surface of the shape of a paraboloid with a variable

Wora circular reflectcr the resolutim . + (measured in radians) is equal to 1.22 )./b , where 2 and D, respectively, are the wavelength of radiation gathered and diameter of the

reflector, both measured ir! the same units. The larger d is, the "smaller" the resolving power is, i-.g.* the ability to separate close snurces of rad€ation. (Tr. note) profile (an antenna of variable profile- AW) the profile depeding on the -altitude of .$he object fradio _source). which is. observed on the meridian with its passage through the mdi-

tivi~.q'i~~atof the radio,. teIescope. The variability -- I.*-. _.

the orofile (the change SheI'pw-%ers the parabolokj " of.. .. -of -of .- -~ - &.-

in extemive objscts, for-example, on the disks of the Sun and Maon, the visible diameters of which are about 32@-31'. For complete localization of smrces (&- both coordinates), obser- .vations must be taken in two azimuths; The radio telescope allows observations to be carried out with shifts of 15-20° to the east and west of the meridian. So arose the !&5c Pulkovo radio telescope (kR) in' 1956, the most powerful radio telescope in the world at centimeter waveleneths. The utilieation of it for radio astronomical obse-rvations warranted all estimates and hooes which were led by it. After 14 years of the radio telescope's use (with several interruptions in connectim with the removal of moving parts of the supports soon after its establishment and reconstruction in 1965-1967 with a change-over to millimeter wavelengt-krs), a se-ies of significant results was obtained; a number of them were mentioned 3n the previous chapter. The inspirer of almost all'af the investigations up to the- end of July 1968 was S. k. fi -.. KHaikin. In 1965, for work in the area of radio astronomy, the Academy of Sciences of the USSR awarded him the A. S. Popov gold medal. Constructional, ideas for the bRwere used as the basis of the design of the gigantic reflectiPe; radio telescope at centimeter and decimeter wavelenPths, the RATAN-600, the con- c struction of which on the Zelenchukskaia plain, begun in 196?,

#-- J W has alrpady nrorressed a areat deal (IU. N. Pariiskii and N. L. J J Kaidanovskii embody the qe?eral scientific leadership with this undettakfrw). A circular fan-shaoed antenna (AVP) with a diameter 201

af 600 getkrsI. and ,-sd-auto~atic contra ~IIOWS oBservations

~:to be.':sltault/ineauS~y..c~~ied.out fn tee&ilsuths with a .-.

resolvi@'-po*F- three thi$e$~-..geattbr.. '%hen f6r -%heLPR; th? use of t?ie whcle:ring~aridthe Gackihg after k.n obsect -of obser- .. .

--=.- ~. , .. --*- to have staried 'with an ex$lo,i.ta$ion of _thef-&ceivingapparatus ..--~ ..-~ . and all metha of '6bsel.vatiohi;- hh a--&eatdeal .of trouble- ,,

was taken. .-bo"ects of prslimina& versions were.,woved. .._ ~ . and i .. i. ._- . replaced -. new eohstruc%&arik-a@. the woeking .mWarxi subse- .. ..

quent~im:3m%ement of methods.. .'ph;e', -. whole ... ..collective of ~ united^ _. . . .- . ~ *-.. . .. the radio astrormqy-- department was consmitly required for t' '5. r\ 7 The LPR ws highly effectively used by-ru' N. Pariiskii a*.d his woup for a. detailed investigation of "discrete sources" of radio radiation. The substantial resolving power of the l!JR since the very beginning of-its work allowed the sizes of iiiio murces and the distribution of the "radio brightness" in them to be determined, and to obtain their coordinates (by means of observations at two azimuths) with the purpose of identifying the radio sources with optical objects. The first significant result was the detection of the galactic nucleus, the intensity of which sharoly increases toward the centar, the determination of its size and mas3 being made according to observations at wavelengths of 3, 10, and 30 cm. The double-peaked distribution of the radio radiatiL;? in the source Cygnus A was finally eatab- 202

lished, and it revealed the erroneousness of the interpretatim of several results regarding this source. which were obtained by meas of a radio intsrfer-ter.l2 A detailed hvestigation was carried out on -radio nebulae" which coincided with optical observations of gasems clouds, such as the Crab lYebula in the cmstellation of Taurus, the Great Nebula in Orion, and the "Omega" Nebula in the constellation of Sagittarius; distinctive .'rai+s were found in the character of the distribution of "radio brightness' for tyoical gaseous (or gaseous-dusty) nebulae and nebulae unich ?resent themselves as supernova remnants (for examole, the Crab Nebula). The coordinates of a large number

l2Hi3h resolution can be reached not only with an increase of tht size of the telescooe (reflector), but also with the help of a radic interferometer- two antennas separated by a known distance and coi-mected to each other with a "h*gh frequency tract," so that the radio srmals brought in by both antennas are added

UD in one receiving aooaratus. The diractivfty dkapam of the radio telescooe has a "multi-petalled" form. Its "petals" are =eater (and also the resolving power), the lareer the base of the Interfemmeter is, i.~., the further the ar,tenna are separated. At the oresent time interfemmeters are used withcut cormctine tracts . 9bservaticns are spchrono!lsly registered on magnetic tape and then deciqhered by comouter and "added up," thanks to the strict synchrnqization. Here thr! high nrecision time service (see p. l3b)fWs an ap-lfc:!tion with the utilization of atomlc s kandards. of radio sources of galactic and extra@actic origin rere determined. After the reconstruction of +e'LPR (1967). new measurements were carried out and a high precision morphologi- cal cataloe of galactic sources of radio radiation was put t wether . Observations were made in parallel fashion of linearly- polarired radio radfation of nebulae at wavelengths of 3.2 and 6.3 cm (N. S. Soboleva and others). The polarization of radiation testifies to its non-thermal character8 for example. the radiation of the Crab Nebula wtly has this character, ard the radio smme Cygrrus A, where a noticeable portion of the radiation is polarized, does also. According to Pulkovo data. abaut 4.5$ of the radio ra'iation for the Crab Nebula at a wavelength of 3.2 cm is polarized. From observations of both the just-men- timed objects (galactic and extragalactic) it follows that the percentage of polarization increases wi,.. the decrease of the wavelewth of the rad12 radiation; therefore, observations at shcrt wavelengths are especially useful. As far back as 1953 /- I. S. SHklovskir set down the proposition concerning the preserxe for the Crab Nebula of an intensive magnetic field, which must decelerate electrow and force them to emit synchrotron radiation in the ootical ard radio-microwme ranges (magnetobrehmstrahlung or the synchrotron effect). The Leniqcrad astronomer V. A. Don- brnvskii ccnf irmed this assumption by detecting the polarized lirrht of the Crab Nebular radio astroncmical results cocfirm this. Polarizatimal observaticns in the millimeter and submillimeter 204

mnms could become a means of searching for supernova renimtnts. the outbursts of which were not earlier observed. fnvestt~ations,conditionally called %pectral" investigations. accrued weat interest. Observations were also conducted at dis+;*c* - wavelemhs, but in the given case it corresnonds to a discrete spectral Xne of some chemical element or compound. Its choice depends-on the purpose of the investigation. For sys- 0 teratic observations at Pulkovo by N. F. Ryrhkov, T. Y. Egorova,

P- b N. V. Bystrova. and I. V. Gosachinskiir two lines were selected: the lines of neutral hydroeen with a navelength of 21 ca, and the hydrcxylaalecule (OH)- 18 cm. Since the time of the discovery of the 21 cm hydroger, line in-1951, radia astrc-nomers at once realized what a powerful wems of imrcstigation they had obtained in the discovery itself, nmely the meazs and not the object, although at first hydrogen was a topic of investigation. Cold, neutral hydroeer. is found everywhere in the galaxy: to distinguish what regime of space it belongs to, it is indeed mssible according to its velocities. which are observed as a rule by the displacement of spectral lines (in the given case by the 21 cm line). Thus, a nap of the distribution of hydrogen was mt toeether. which crashically showed-that our galzxy. indeed. oresects itself as a sciral system, the arrangement of the sfiirals (arms) and the direction of motion of hydrogen in them now being known. although in need of beina more accurately determiTed. In passinq, it is indeed nossible to more accurately determine the ma?. The ftindamental prcblem of Pulkovo radio astror.orners xsists of utilizinle: the known distribution of hydrogen, in order tc obtain accurate information cancernine other sources cf radio radiation, their arrangemefit or structure (if the spurce is extended). In this case interstellar hydrogen is als- used as a means of investigation. Its line at a navelerjrth 2f 21

CB, considered till now 'a mess" because of its irregular cm- tour and the washed-cut ap-earance of its Breadth, was shonr. to be extraordinarily "advantagems" for the investigatcrs. This line nresents itself as a whale assemblage of frequencies, which corresponds to hydrogen moving with different velccities cbserved along the line of sight. Tming in several frequencies nearby the frequency of 1420 Mht (wavelewth 21 cm) and sir.ultanecusly taking informaticn in several channels (in the ?ulkovc, installation there are 10). radio astronomers 'lcrk throirgh" all of the plaxy's soace in the dated, -i.g., it is r.ossible to e..:tfmate the ciistarce to it, ard its ccordinates are determined with the directlor- of cbservation. The suhstantial res-lvirp pnwer of the LPR allows this tu be 206

done with sufficient accuracy (the reidvi~power for a wavelength of 21 cm is seven times "mrzefi*than at 3 cm). If the investigated source ap2ears to be dsskle, the "3ulZcv- methxi" allows the determination of whether bo' h scurces are ohysically connected to each rther (they arc situ .9ed in one velume of snace), or whether they accidefitally 15e on tc3 of each cther alorra the line of sight.

In such a way a laree fium3er of rdi- scurces was investieated. Of course, the first object Df invest5gaticn was the ealactic nucleus, and in a more recent representation Ff it as a scurce Dossessing strict s-vnmetry -elative to the direction taward the galactic center, essentiai ama.erxicent= to the repre- sentatim came to be in:r.-:duced. At fixt other cbserve1'S. in ?art:-czlar, Australia- radio astronomers, could not verify the results of the PulkovD rat?io astromaers. But the res-dt was also cn?.firrned wlth the obse,-vaticn of thc hydroxyl il( lecule lines at 18 cm at the very same Pulkovo irstall-ation. The hy- drqxyl molecule, like neutral hydrocer., is LASO used ir? the caoacity of a means cf investigatim, bi:. its distribution in snace has still hardly been studied, md therefcre, it presents itself, excent for what was just i,.entiznei, its ai object c?f investisration. Accnrdinp to Pulkovc dat-, IloGds of hydrzxyl m-lec.les Dossess different motions j3 snaco ana d? not match those of hybrcpsn. Most ISke'r, *hLs is not acci2ental: hydrG.ql molecules &:e very erereeti : a:*.idizers; they "readily" entar into rtacti-ii with alcost. e y chemical elc:i?er.t (in cmbsnaticn with hydroen they make water). In other words, the hydroxyl malsc-31% is the "building material' in the galaxy. But from whence it c-mes and into the creation of what it sees, is not well knwn at present; not withxt reascm it has been called "mysterium. '13 Attemyts to unravel the mysteries of ccsmic hydroxyl clouds, an3 at least firtd some ap?rcximate aRswsrs ta the questions, cmtinue at Pulkovo. Arcother direction of spectral (radio astronmical) investieations cnnsists of the detection of new lInss of mcmchro- P F. watic radio radiaticn. In 1958 N. S. Kardashev (GAISH)- calculated the "erereetic transitions' of a series of radio lines of excited hydroze- and indicated the cossibility of their prirtr. ?SI ka5Ct-b q)Or 7 beit-$ n3senred. In 1963 the 4 Astrwxmical x\ colleagues A A. F. and 2. V. DravsEkh detecterl one of tb,,ose lines with a wzvelewth of 5.1 cm in the radic radiatio:. of the "Qrneei' an3

0- 0 Crion Nebulas. Some t'me later R. L. Sorccher:Xo ami E. V. Eorod- r- esch (FIAS, loscow) ohserved one more line of the same series wtth a wavelewth nf 3.4 cm. The report of both of these ais- cwer5es at the IAU conference in Ha!Surg (1964) was met with great aporoval. All five authors ware hoznred with a dipl.>ma for the diszco-;ery, registered in 1966 by the C3m.ittee for

1 -3Thore are ?ow xany ssch "mysterisms." Zxcezt for OH, a va?iety of "buildine materials" has Seer: c3served by rdio astronnrninal rnetir-ds ir! interstell-lr SGzcer water, forna1dehy5eD several alc-hcls, etc. 208

Business of Inventions and Discoveries of the Council cf Einisters of the USSR. A -quasars service" was systematically put into zperation with the helo of the LPR, rhlch was conducted on an internati-nal scale for the study of their radio variability. In 1963 ootical. variability was shown on old photceraphic ?lates by n r\ two Koscow astronomers (A. So SHarov arxl IU. N. Efremov), acd shnultanecusly by two American astronomers (H. Smith ard D. HofCleit), soon after the discwery of the red shift of the lines in the spectrum of the quasar 3C 233 by M. Schmidt. The disolarement 02 the spectral lines towa-rd the red end (if it is to be interpreted as Doppler-like) indicates the recession of the scurce. The size of the displacement (the velocity of recession) testifies to the enormous distance to a quzsar. From the apcarent stellar magnitude and the known distance, the absolute stellzr maer.itude (luminosity) can be calculated, on the basis of which it car?. be concluded that a quasar radiates 100 times more erergy in the optical part of the spectrum than our whole elaxy. Gn the ather hand, the variability of its brightness indicates that this is a sir?zZe bTdy, and not a cowlomerate. The exolanztlon of the variability of quasars w;th the neriodical and co-rdin:tted outbursts of a hundred suuernovae was rejected. From the Yeriod of variability (frm several days to nne year) it follows that the diameter of a typical quasar daes not exceed 1 light-year. The sites, indeed, are small for a bcdy with 100 bill:m solar masses. These sizes are confirmed by aeasuremerts at the time of occultations of a quasar by the Moon and in the features of radiointerferometrfc measurements: the diameters of quasars seen to be significantly smaller than the visible sizes of the nost distart gklaxies. Till 1967 the radio variability of quasars remained in dsubt: the -?eriods, cot observed with certairty, did cot cotn- cide with thnse detected op?ically m phctozra?hs. At Pulkovo N. M.’Lipovka obtained a most prolonred series of radio observations of the quasar 3C 273. A 10-day period of radio varla- bility was found for it, although the radio observations of the varfa3ility were more com2licated than the ogtical nbservkticns because of ohtacles which arise in the cosmos itself, in inter- nlanetary and interstellar space. Confijent series of radio observations of quasars could be obtained on the basis of international coonerat!on. “Closely soacej seri5s” of observaticms are necess‘try for the revc ling of short Deri2d variations. Ob- servations of several quasars ?re cnnducted at Pulkovo at a wavelenrrth of 6 cm (1963-1967) and at 4 cm (since 1967); at t’mes they were taken every day with each passil?e cf the quqsar through ths neridian. The joint study of the variability of qujsars wlth radio astronmical and optical methxis ?robably sheds lirht on their nature. Finally. let us take one riore lwk at radio observations which are im.:ortant for cosm-logy. Lktely at Pulkmo attempts have beer made to discover fluctuaticns in the b-.ckercund raciia- tiqn. As msntioned earlier (see p. 181), the discovery of the 210

backermund thermal radiation was taken as indis3utable eviderce ir, favor of a non-statiwary model cf the universe. which was hot in the past. Indeed, if the universe was formed as a result of a bie bane, with which the temcerature reached billions of demees, then with the expansion it must have cooled down. The remainder of the radiation which 5s observed in the present epoch at different wavelenPths of the radio spectrum leads to a single backmound temoerature of about 3' K (3 decrrees above abs-lute zero). L.n.8 this is not sane kin4 of special radio radiation and is mecisely thermal radiation. In the optical range of the snectrum the radiation hss such a low temperature that it cannot be observed at all- ancrther advantage of radio astronomy. Pro- bably, the backfrromd registered by radio telescopes brines us infnrmation from the nost amient period of the universe (Keta- gslaxy), durine which the fcrmation of quasars and galaxies besan. 'cut is this backqround cont;nuous? Is it impossible to prck out senarate fluctuations. "clumps of energy," fr3m it? Gal;leo also row:'.ly viewed the mysterious Milky Way, layed out in stellar clouds and separate stars with the only difference beirig that he

"did not look" so far into the nast universe. In other words, is it imossible to observe that which came before galaxies and quasars- protogalaxies and nrotnquasars? Havine asked such questions, Pulkovo radio astronmers obtained a neqative answer. With great precision it was oossible to show that the backlrround has a structureless chtAracter. Ap- pareptly, between us and our most distant past, is situated a 211

"cmtinucus fog" in the form of-an "electron gas undereoing ThamCsan scattering." Such was the result of the observations and its unexpected interpretation. 212

CONCLUSION

We returr, to our life. Arriving at Pulkovo Observatory with a tour or alone, the conglomeration of towers is astonishing, the fantastic outlines of the ,domes, like the originals, used with some fantasy, as in abstract art, although this is no abstraction and no fantasy, rather, art expedient realieation of concrete projects with strictly scientific objectives. The strikingly flat metallic "semi-circular fence" - the fan-like antenna of the Pulkovo radi helesco pe \ with multiply repeating tuning mecnanisms or! the back side- attracts one's attention. And nearby are the bowl-shaped metal- constructions of radiotelescoqes of different sizes with retina or continuous reflecting surfaces. Almost all the structures are original, every one of interest. At Pulkovo there are architectural and historical monuments. Already at the entrance at the foot of Pulkovo hill one's attention turns to a stone arbor-fountain (architect nomas deThomon, 1809) standing to the right of the highway. This is one of.three- remain- ing ponds, some time ago standing on the Saint Petercburg-TSarskoe Selo road (twc of the others were transferred to the city limits). On the ascent of the Kiev hiehway one meets another architectural structure- an ancient ecrotto, made in 1807 according to a project F .* of A. 3. Voronikhin from Catchina limestone. In the Circular Reception Hall of Pulkovo Observatory there is a portrait gallery cf distinguished astronomers of the XVIII- XX centuries. A portion of the portraits 5s situated in the reading gallery of the science library. A collection of oictures (about 50) fills up the extent of the whole history of the oarticipants. In the majnrity of them the portraits, painted in oils, are originals and were executed by well known masters c)r present theaselves as good copies of the originals. Among them are two portraits of Wilhelm yon Struvet one in the library, ne made from a photograph of 1864 by N. L. Tiutriumov, the Dther, the work of the notable Danish Dortraitist Christian-Albrecht Jenser,. Several copies from portraits of forEign astronomers, located in the Circular Reception Hall, came from his brush. A There are portraits of: A. P. Briullov (original?), in L rendi- P fs tion of his brother K. P. Briullovr %to Struve, and A. N. Savich (originals)- works of the distiwished Russian pointer I. N. 4 Kramskoit 0. A. Saklund, in a rendition of anather artist-copyist, N. P. Boedanov-Belskiri fi. 6ylh , the work of the great Swedish artist 0.6;'%&: D. Gill, in the origiral impressionist brush style of h'za Baklund, oldest daughter of 0. A. Baklund, a well known artist, especially i.-r the oeriad of her liie in Sweden since 1916: P B. P. Cerashovich, made in 1957 by the Leningrrad artist N. G. Lopakinr and many others. In the very same Circular Receotion Hall (the form of the circle has only a stcne flnnr in the interior part of the hall, separated by massive columns from the sxterior part in the form of an octahedron, where, in essence, exhibits take place) a pho- toeranh!cal shew was nlhced, which was devoted to the history and scientific activ'ty of Pulkwo Observatory and its branches, 214

and also there is situated the museum of astronomical observa- tima1 equipment, various clockss demonstrating the development of measurement of the "custody of time," visual receivers and laboratory aoparatus, seveml manuscripts and a few books, per- iodically having been presented for review. Having existed until the war, the museum of old instrumenta was entirely destroyed: the present day collection was created anew in 1965.

In the central part bf thz Ball, on the Pulkovo meridian, in 1964, at the one hundredth anniversary of the death of Wilhelm von Struves wz . +ed his marble bust, in a rendition of

the Leningr.-*i * . A. Teplov. Outside (.. Glnises, in the niches of the northern facade of the main building of the observatory, are established the sculptures of the most notable astronomers who destroyed geo- centrism and who gave expression to the developmepjt of modern remesertations of the cosmos- Nicolaua Copernicus and Galileo Galilei (the sculptors were L. I". Eldlin and L. N. Barbas). OpDosite to the entrance in the small building of the seismo- logical station, having an attractive view of the metropolitan dachas or private summer homes, in the neighborhood of the painted Petrov stone mound, on a pedestal of red granite, towers a bronze bust of the founder of the station, the academician

A Grand Duke B. B. Go1;tsyn (sculptor N. Koghutov, 1955). To the northeast of the main buildin%, on a stee? slope of the hill, is situated a metwrial cemetery of astronomers. Here is buried the founder of the observatory Friedrich Georg Wilhelm Struve, next to him his wife Johanna Franciska Struve- 1 W Bartels (1807-1867), 0. A. BaklUnd, A. A. Relopol'skii, S. K. 4 / n L- Xostinskii, G. N. Neuimin, S. I. Beliavskii and many workers hlkovo, wlose memory and business science and the history hlkovo Obssrvatory oreserves. On the nortr:ern slope of the hill, sinca the time of the lsst -8 a milttarv cemetery with communal paves was formed, on which those who perished were enumerated and with nameless graves, which also are reverently protected. A large communal grwe of the guardsmen is situated on the Pulkovo meridian, on +ha the summit of the hill, in front of facade of the main building of the observatory. On the cemetery lawn is a modest monument of grey granite with a marble slab and the laconic inscription, carved in gold: "Zternal memory tc the heroes-guardsmen hav;.ng perished in defense of the city of Lenin. January- 1944."

That unforgettable January cost so many lives! Sacrifices were made but not in vain: Crawing here, the enemy found then only its destruction, as they found it on other fields of battle in the war which undid them. Yearly, thousands of peode from

'This was the second wife of W. Struve. His first wife, Emily Wall (1796-18341, died in Dorpat, having left after her eiyht children. The necessity to bring them up wi?s left to the second marriage. Of the second wife of W. Struve his son Otto Struve spoke not o~lyconcernine: the suitable choice of his father, but about the mcther dear to all the children. 2%

different topers GL' the country visit Leningrad and Pulkovo, ir, order to see the place of t?e bloody bat'les and tc bow their hea%isfcr the brzvery and those who Derished with courage and

"races of ths last battleLc are preserved :o the south of the observatory in the appearacce @f an anti-tank ditch, having eroded in places, passirg over the Kiev highway to the I

Cn ?~thsidec cf the hishwsy, which crosses the Pulkovc River, stand tnc rectilinear form structures of solid ccncrete, with the deenly embed.!ed fizures "1941-1Q44." The ,tone massifs one azd a haif kilometers fmm the south gates of the observatcry designate the one-time bcur?dary of the frmt, having stabilized after 28 mor:ths. Within three hutxired meters of tke very gates, ~m the left side of the road, a grsndiose mcntiment was buflt in 1947, in the form of a mural with mosaic designs, portray5.r-g the heroic victory of the Leningrad trcops in the Great Pztrictic

War. The cr-ject cf the mrnumect was worked qut at the LeninPrad

P Hieher Artistic-Industrib1 Academy by V. I. Mukhir,a , under the r 1e:rdershlo of its rector 'IA. N. Lukin. Ard ar. even more subllme mcr?.ume!?t to the heroes-defepders nr' Lecinmad is Pulkr.;rc Observatory itself, restored at the fcrk ir. the road and Drnsnerine to the glory of Russiar science and t~ the elcry of the hemic clty ad its Metherland. Ashbrook, Joseph, "The crucial years of Wilhelm Stmve,"Sky and

Telescooe, V. 23, no. 6 (June 1963). p. 326. Brouwer, Dirk, and Nassau, Jason J., "The dedication of the new

Poulkovo Observatory," Sky and Telescope, V. 14, no. 1 (Novemkr

199). Do 4. F. CI Dadaev, A. N., Pulkovskaia Observatoriia (Pulkovo Observatory), #scow-leninerad, 1958; also in English. /r P Duzhnikov, IU. A.. Pulkavskie vvsoty (Pulkovo heights), Leningrad. 1964 . r r Slavnsia astronomicheskaia observatoriia Akademii 1 Pulkove (182p-1952) (The Principal Astrcnsmical Observatwy of the Academy of Sciences of the USSR at Pulkovo), Wcscow- Leninmad, 1953.

#- e c - Cnevyshev. M. N., Kislovodskaia nordia astronomisheskaia ~tan- c -- tsiia (Koslcvodsk mcuntain astroncmical station), Hoscow- Lenimrad, 1965.

L ,-- A h?ikhailov, A. A., Astronmicheskaia stolitsa mira (The astronomical caoital of the wcrld 1 , stenoFra2hically nublisher'; lectures, Leninrrad, 1951 . - .-- c Wikhailov, A. A. , Pulkwskzia observatoriia (Pulkovo Cbservatcry),

MDSCOW, 1955.

./' L Mikhailov, A. A., ed.* Vasilii IAkovlevich Struve: sbornik statei

P -e --k lOO-letiic co dnia cmerti (Vasilif IAkovlevigh Struve; collirc- tian of articles at the hur?~redthyear since his i,eath), Moscow, 1964. 218

Newcomb. Simon, reminiscences of an astronmer. Bostcn and Xew York. Howhton. Wifflin and C0.m 1903. pp. 114, lk5, 309-

n 0 Novok&acova (Sokolovskaia) . 2. It. . Vasilii"- IAkovlevich Struve, UOSCOWm 19&. Otkrvtie rosstanovlennor- Pulkovsko'i observatorii t sbornfk dokladov, wstuDlenii, privetstvii ('Phe inauguration of the restoration of Pulkovo Obsemtoryt collection of lectures. sneeches, salu- tations). Hoscor-Leningrad, 1955. v e Pulkovskoi observatorii 125 let; sbornirr statei (Puikovo Observa- tory's 125 years; collection of articles). Moscow-Lenimad, 1945. --Sto let Pulkovskoi observatorii; s5crnik state; (One hundred years of Pulkovo Observatory8 collection cf articles), Moscow-Lenimad,

Stnave. Qtto. and Zebergs. Velta. Astronaw of the 20th Century, New York. MacMillan. 1962. VmSOtSkym Alexander No. "RemirGscences of Pulkovo Cbservatory."

Sky and Telescooe, V. 24, no. 1 (July 1962). p. 12.

Lecture artiJles of a more soecial character are located in the "Proceedincs of the Princlszl Astronmical Cbservatsry at Pulkovo." nos. 154 (1955), 160 (1957), 176 (1969, 177 (1964), ar.d 185 (1970).

220

Afaras'eva, P. Z., 132 iikhur?dcva, 3. V., 146 Al'bitsk::, v. A., 95

Asten, E., lis

falanovskli, I. A., 39.93 221

n- Bialshin, C. F., 16a SjGrck, sustaf- .sirar, 213

U 3wdanov-3elskii, X. P., 213

c Boavdskii. A. F., 98, 186

E!oss, Penjamin, 122

5s. 37

Zystrova, 3. V., 192, 294

Clark, Alvar, 5c Sons, firm of, 27 222 - Deich, A. N.. 88, 104, 118, 139, 143, 144, 146, 148 Denidova, A. R., 191 Dervit, T. E., 164 -% Dichenko, 1. P., 52

I Dneoravskii, N. v., 81, 83, 86 /- Dobychin, P. V., 111 Dollfus, Audouin Charles (1924- ), 30

Y Dcrmbrevsicii. V. A., 203 Doppler, Jchann Christian (1803-1853). 36 -3 Dravskikh, A. F., 175, 203 .? Dravskikh, 2. V., 207 Drozd. A. D., 37 Enrlinetcln,- Sir Arthur Stanley (1882-1944), 185 Bfrenov, IU. 3.. 209 Zgorova, T. M., 204 ‘1 kidlin, L. IU.. 214 &er?s*n, 1. S., 95, 98, 104, 186 Einstein, Albert (1879-1955j, 179, 185 Elistratnv, V. A., 99 Enikeev, A. V., 107

Ertel, master, 10

Euler, Leonhard (1707-1783). 41

Fatchikhin, N. V., llS Peclor-v, E. P.# 127 Feil, flrn of, 27 ?esenTicv. V. G., 185, 13Q Piearo, 3. A., 139 Fizeau, Arrr.a?d iiiomlyte Lcuis (1819-1¶90), 36 F-fsrova, T. Z., 101

Puss, C. (3. 1854), 11 224

Crubb(-Parsons), fir3 of (Dublir?.), 43, 71 Cglden, Hueo, 45, 53, 213 Hall, Asaoh (1829-1907). 27 Hasselberg, Clas Eernhari (l??@-l922), 25, 26, 34, 41, 50, 93 Henderson, Thomas (1798-1944), 6 Henry brothers (Paul and PrnsDer), firm of, 35 Herschel, William (1738-1822), 25, 18%

Hoff, S.. 51 Ifaffleit, Ellen 3orrit (1907- ), 205 3nyle. Slr Fred (1915- 1, 185, 195 Ifubble, Sdwk Powell (18s9-1953), 81, 32 %umbolOt, Saro2 irlexaq3er von (1769-1859), 184 Idel'scn, 13. I., 70, 194 Ikhsaznva, V. N., 175 Innes, Rcbert Th?rhurr. Aytcn (1961-1933), 144

IoanniS!2??!, Bwat K., llb Ioffe, S. 3., 109, 165 0- .? - I'i'Cenich, Ge?eral ::iX3lal Fiikclaevich (1462-1933), 2 .? It'dtna, I. V., 167 ,,-. Ivar?-v, Alekandr Aleksandrnvich (1967-1939). 4, 33, 43, 64, 69, 76, 98

I Jarssen, Fierre Jules Cesar (1824-1907), 40 Kanaev, I. I., 147 Kapteyn, Jacobus Cornelius (1851-1922), 57, 60, 88, 89 0 Kardashev, N. S., 207 J Karpinskii, V. Nor 167, 173 Kertrnbekov, Yt., 167 t- KHaikin, S. (19014968). 197, 198, 200

Kostina, L. D., 128 c-. Kotliar, L. M., 167 Q KOValeVSkah, S. V., 40 e fi Kozyrev, Nikolsf AleksaRdrovich (1908- ID 96, 97, 149, 151, 226

J Kranskoi, I. No, 213 Krasin, L. B., 72 4 Krascvskii, V. I., 194 Krat, T. V., 161, 163, 169, 170, 171 n Krat, Vladinir Aleksserich (1911- ), 97, 98, 104, 159, 163, 164, 166, 167, 169, 186, 187, 188, 191 /- Kucherov, #. I. (1905-1964), 114 Kucherova, V. No, 161 Kuiper, GerarZ Teter (1905-1973), 59, 144, 153 t- Kukarkin, Boris Vasilievich, 106, 185, 190 P Kuorevich, N. F., 113, 155, 163 Kktner, Friedrich (1856-1936) , 41, 42 n Kuznetsova, T. N., 192

Iehan, I. N., 39 r\ Lehrnan-PJalancvs'rzia (see Balancvskaia-iehman) r Lemai tre, Abbe Georees Edouard (1894-1966) , 185 c bntsman, V. L.8 156 Lindemann, E. E., 24-25 P Linnik, Vladimir Pavlovich (1889- 1, 111 LiLovka, N. M., 2?9 Lockyer, Sir Jcseoh Komar. (1836-1920), 40 Ln9akin, N. S., 213 f' Lukin, IA. N., 216 227

Mahler . Jose Dh, 11 Maksinova, E. A., 65 P hksutav, DmitrG Dnitrievich (1896-1964), 72, 75, 113, 114 0 blal'tsev, N. So, 48, 49 0 Markov, Aleksandr Vladimirovich (1897-1968), 113, 150. 131. 163

Markawitzr,fl William (1907- 1, 137 '- n Matkevich, L. L- (1878-19491, 65 n MelenlXov, Oleg Aleksandrovich (1912- 1, 56, 104, 111, 114, 164, 188, 191 Merblov, A. Yo, 134 Mere, Georg (1393-1867), 11 J n Mikhailov, Aleksandr Aleksandrovich (1888- 98, 1058 106, 112, 125, 139, 150 n Mikhel'son, N. No. 113, 114, 163 A Miloradovich. E. P.. 46 Hitrofan-va, L. Am, 158, 164 0 hiolcha?ov, A. P., 135 Moreran, Herbert Rollo (18?5-1957), 122

NeTiro, A. A., 81, 122, 125 " r Neuimin, Criscrii Nikolaevich (1886-1946), 64, 102, 105, 215 h'ewcmb, Simon (1835-1909), 13, 15, 16, 42 Nikon-v, V. B., 194 Nordmann, C., 56 Olber8, Heinrich Wilhelm Matthias (1?58-1849), 13 Onegina, A. B., 146

Oort, Jan Henarik (1900- )s 185 Oosterhoff, P., 115 Orlov, B. A. (1906-1963), 33, 81, 111, 123 Orlova, if. S., 130

Orlova, 0. l;., 146 -. *-. .--. Ostashenko-Kudriavtsev, B. P. 48

Pacova, G. V., 139 -1 Pariiskii, IU. N., 157, 197, 200, 2@1 Parsons, W. (see Rosse) Pavlov, N. N., 101, 104, 105, 109, 110, 126, 120-132, 135, 136 - ,.7 Pzchinskaia, N. I.# 173

h Perepelkin, E. 'IA. (1906-1937), 89, 91, 93, 168 Peters, Chrtstian August Friedrich (1806-1880), 11, 13, 16, 41 Pe+rov, S. S., 99 r Pliug!in, C. A., 147 P. Polohentsev, D. D., 121 Ponomarev, N. G., 75, 99

POOW, v. s., 191 Potter, KH. I., 126, 137, 149 Powker, G. E., 28 Pravdiuk, L. N., 169 Prokof’eva, I. Am, 113, 165, 170, 171 Renz, P. F., 58, 75, 99 Remold brothers (Johann Adolf and Oscar Philipp), firm of, 10, 27 Rom’Serg, H ., 52 c. Romanov, Konstantin Konstantinovich, 70

A /- Romanskaia, S. Y. (see Voroshilova) Rasen, P . - 24 c Rose, William Parsons, 3rd earl of (1800-186?), 28 f- Rubashev, B. 95, 1?6, M., - 177 Russell, Henry Norris (l8??-1957), 193 A RmhkaV, Nm Fa, 204 Sabler, G., 11 P. Sakharov, V. I., 128. 129

.0-- Savich, A. Ne, 213 Scheher, Julius (1858-1913), 57 Schiaparelli, Giovami-Virginio (183501910); 31 Schjellerup, Ch. (182?-1887), 52

Schmidt, Maarten (1929- 1, 208 Schwarzschild, Karl (18?3-1916), 196 Schwarzschild, Nartin (1912- 1, 166 Serafirnov, V. V., 33, 52

Severnyi, Andrex Borisovich (1913- ), 106

,-. e _A SHain, Grieclrii Abramovich (18924956) a 94 Shaoley, Harlow (18R5-1972), 81, 82

SHarov, A. S., 208 SHCHtsolev, D. E., 139, 140, 151, 192 ' '. SHCHusev, A. V. (1873-1949). 107 ,- L SHklvskii, I. S., 203 ,. ,. ,- SHmidt, 0. IU., 185

<- SHul'man, B. S., 99 .-. Sliusarev, C. C., lo9 Smith, Earla (1924- 1, 208 Sebolev, V. M., 169 Sobolsva, N. S., 175. 203 - - Scfrrnitsskii, A. V.. 191 Snkolov, A. P., 43 Sorochenlo, R. L., 207 Staritsyn, G. V., 126, 132 Stoianova, M. N., 169 StOYkO, 3.. 135 Strand, Kaj Aage (1907- 1, 146 Y .. Strugatskii, 9. N., lk-9 Strul-e, Zmily Wall (l796-1834), 215 Struve, Friedrich Georp Wilhelm vcp. (1793-1864), 3, 64, 10-13, 16, 17, 20, 22, 79, 81, 83, 87. 185, 213, 215 Struve, Georg Cttc (1886-1933), 3!: Struve, Gustav Wilheln Ludwig (1858-1920), 30, 31 Stwve, Karl Hernann (1854-1920), 29, 30, 35 Struve, Ctto (1897-1963), 31,'llJ Struve, Otto W'lhelm (1819-1305), 11, 20, 22-25, 29, 39, 31, 32, 59, 213, 215

Struve-Bartels, Johanna Frz. n;c' 3 (1807-18671, 215 n SUICIWSV. L. A.. 113, 125 c. Tavastsh*ms, KO No, 123 Tenlov N. A., 214

UlsoVD No Am, 39 Vastl'ev, A. S. (1868-1947). 52, 87 Vasil'ev, V. Men 130 fi Vasil'eva, G. IA., 168

7- 7- r. Vialshin, C. F., 170 VTazani$yn. V. P. (1908-1960), 91, 162 Vil'ev, M. A., 64 n Vitinskii, IU. I., 171, 176, 177

P. Vxmikhin, A. 212

1- c Voroshilova (Romartskaia), S. V. (1886-1969). 47, 70, 127 Woolley, Sir Richard van der Riet, 123 P Zeibot, IA. M., 52 Zeiss, firm of, 74 .' n - Zel'd-v!ch, IAkov 3crism *h (1914- 1, 181, 185