Figure 6.1: Above: The Nicholas Central Astronomical Observatory (Pulkovo Observatory) (the view before WWII) Below: The restored Pulkovo Observatory (the view after WWII) (Pulkovo Observatory, St. Petersburg) 60 6. The Pulkovo Observatory on the Centuries’ Borderline Viktor K. Abalakin (St. Petersburg, Russia) in Astronomy” presented in 1866 to the Saint-Petersburg Academy of Sciences. The wide-scale astrophysical studies were performed at Pulkovo Observatory around 1900 during the directorship of Theodore Bredikhin, Oscar Backlund and Aristarchos Be- lopolsky. The Nicholas Central Astronomical Observatory at Pulkovo, now the Central (Pulkovo) Astronomical Observatory of the Russian Academy of Sciences, had been co-founded by Friedrich Georg Wilhelm Struve (1793–1864) [Fig. 6.2] together with the All-Russian Emperor Nicholas the First [Fig. 6.3] and inaugurated in 1839. The Observatory had been erected on the Pulkovo Heights (the Pulkovo Hill) near Saint-Petersburg in ac- cordance with the design of Alexander Pavlovich Brül- low, [Fig. 6.3] the well-known architect of the Russian Empire. [Fig. 6.4: Plan of the Observatory] From the very beginning, the traditional field of re- search work of the Observatory was Astrometry – i. e. determination of precise coordinates of stars from the observations and derivation of absolute star catalogues for the epochs of 1845.0, 1865.0 and 1885.0 (the later catalogues were derived for epochs of 1905.0 and 1930.0); they contained positions of 374 through 558 bright, so- called fundamental, stars. It is due to these extraordi- Figure 6.2: Friedrich Georg Wilhelm (Vasily Yakovlevich) narily precise Pulkovo catalogues that Benjamin Gould Struve (1793–1864), director 1834 to 1862 had called the Pulkovo Observatory the “astronomical (Courtesy of Pulkovo Observatory, St. Peters- capital of the world”. burg) They served for decades as a reliable basis for fur- ther compilation by Simon Newcomb, August Auwers Abstract and Lewis Boss of the fundamental catalogues which contained data on stellar positions and proper motions The present paper deals with development of astrophysi- and incorporated the astronomical, celestial, frame of cal researches at the Pulkovo Observatory (now: the Cen- reference as frozen on a definite date (an epoch), i. e. tral (Pulkovo) Astronomical Observatory of the Russian for the begin of the Besselian annus fictus as designated Academy of Sciences) at adjacent time periods separated by above by using the symbol ‘.0’. the threshold between the XIXth and the XXth centuries. From the first days of Observatory’s existence the The Pulkovo Observatory, had been inaugurated in 1839. considerable attention had been paid by Wilhelm and Its traditional field of research work was Astrometry. The confirmation of the light absorption phenomenon in the Otto Wilhelm Struve to establishing an astronomical interstellar space by Friedrich Georg Wilhelm Struve had library which later was called by Simon Newcomb to marked the turn of the Observatory’s research programs to- be the “main instrument of the Pulkovo Observatory”. ward Astrophysics. Extensive catalogues of books and manuscripts (among New tendencies in the development of the contempo- them the famous manuscripts of Johannes Kepler!) of raneous astronomy in Russia had been pointed out by the Pulkovo Library were compiled by Wilhelm Struve Otto Struve in his paper “About the Place of Astrophysics and by Eduard Lindemann (“Librorum in Bibliotheca 61 Speculae Pulcovensis contentorum Catalogus Systemati- It should be noted that on the time span from 1816 to cus”. Tomus primus, 1845, tomus secundus, 1880). 1855 geodesists of Russia, Sweden and Norway (“trium gentium geometrae” as sculptured on the obelisk mark- ing the Southern terminal of the meridian arc) under permanent guidance of Wilhelm Struve had performed the immense work on astro-geodetical measurements of length of the meridian arc extending from Hammerfest (Fuglenaes) in Norway to Ismail (Staro-Nekrassowka) in Russia and being 25∘200 long. This meridian arc had been later named the “Russo-Scandinavian Arc”, or the “Struve Arc”; the measurements of it had served as a basis for establishing the Earth’s size and shape. They were in full detail described by Wilhelm Struve himself in his book “Arc du meridien de 25∘200, entre le Danube et mer Glaciale”. The Pulkovo meridian passes through the center of the Round Hall of the Observatory which is marked by the post on the floor symbolizing the origin of the geographic system of reference of Russia [Fig. 6.5]. The assumption about existence of the light absorp- tion in the interstellar space was made in 1840 by Wil- helm Struve, the first Director of the Observatory. The confirmation of his supposition in 1847 to be true which had been obtained by Wilhelm Struve from his profound analysis of the apparent distribution of stars and given in his well-known work “Les Études d’Astronomie Stel- lair” may be considered as the first result of an outstand- ing astrophysical significance obtained at the Observa- tory. It was of the decisive importance for solution of the Olbers’ photometric paradox (1826) having a major impact onto Cosmology and Philosophy. The steady development of the astrophysical research in the astronomical world community has been reflected in the communication read by Otto Struve (1819–1905) [Fig. 6.9], the second Director of Pulkovo Observatory, in 1866 in a session of the Petersburg Academy of Sci- ences, and entitled “About the Place of Astrophysics in Astronomy”. The very first astrophysical (rather geo- physical) observations at the Observatory were made by Otto Struve in 1868 who observed together with August Wagner the main lines in the spectra of the Aurorae Borealis. Problems related to the Astrophysics were included into the plans of the Nicholas Central Astronomical Ob- servatory’s research works at the time of the directorship of Otto Struve, so that he ordered in 1862 the Schwerd photometer which was obtained in 18651 shortly before the end of navigation, being installed only in 1866 in the tower specially erected for it because of the bitter frosts in the winter of 1865/1866 [Fig. 6.8]. This event had been noted by himself in his annual “Report” about Ob- servatory’s activities covering the time-span from June 1865 to May 1866. Otto Struve had written: “Due to the acquirement of the photometer the Observatory is now equipped with one of the main instruments for perform- ing the astrophysical research”, adding, however, also the following remark: Figure 6.3: Above: Czar Nicholas the First (1796–1855) Be- low: Alexander P. (Aleksandr Pavlovich) Brüllow “This will still more split up our forces and distract the (1798–1877) (Courtesy of Pulkovo Observatory, astronomers to such themes which, although belonging St. Petersburg) essentially to the Stellar Astronomy, do not bear any 62 Figure 6.4: The sectional view of the Nicholas Central Astronomical Observatory (Pulkovo Observatory) in the First Vertical Plane (Pulkovo Observatory, St. Petersburg) similarity to our main works because of the kind of their metric measurements for stars of various stellar magni- performance and of the state of their development.” tudes. Eduard Lindemann (1842–1897) [Fig. 6.6] had But from the other side, Struve agreed with the ex- begun to work with the Zöllner photometer in 1873 and traordinary importance of the astrophysical data con- observed the same star groups as Per Rosén did and by cerned with the properties of celestial objects and, there- 1874 he made already ca. 400 determinations which al- fore, he asked Giovanni Donati who was the director lowed to find out the luminosity ratios for stars from the of the Physical Observatory in Florence to take his 3rd to the 9th stellar magnitudes. Eduard Lindemann personal care and supervision over manufacturing the measured the stellar magnitudes until 1884. spectroscope for the Pulkovo Observatory which had His main results were published in the mono- finally arrived in Pulkovo in 1865.2 Moreover, due to graphs „Helligkeitsmessungen der Bessel’schen Ple- the increasing value of the Astrophysics in the astro- jadensterne"’ (1884) and „Photometrische Bestimmung nomical world community Otto Struve had acquired the der Grössenclassen der Bonner Durchmusterung"’ spectral device from Georg Merz and the photometer of (1889). Otto Struve noted in his “Reports” that the Karl Friedrich Zöllner. The Observatory obtained from weather in Pulkovo considerably hindered these observa- London the three instruments for the observations of tions, and in his letter addressed to Leopold Berkiewicz the passage of Venus across the Sun’s disk: the photo- (1828–1897), director of the Astronomical Observatory heliograph, the portable heliometer and the portable of the New-Russia University in Odessa, and dated refractor. In his annual “Report” for 1867 to 1868 Struve April 21, 1873, he proposed to perform there astro- wrote: physical and photometric investigations. These works “The permanent increase of the importance of the As- were continued at the Odessa Astronomical Observatory trophysics has prompted me in the past year to increase by its director Alexander Kononowicz (1850–1910), the the amount of instruments related to these subjects, i. e. successor of Professor Berkiewicz, who published sev- to order the spectral device from Georg Merz and the eral monographs on photometry [\Fotometriqeskie Zöllner photometer.” исследования planet Marsa Юпитera Saturna" After these instruments arrived at the Observatory (Photometric investigations of planets Mars, Jupiter the observations with the Zöllner photometer started and Saturn), \Opredelenie al~bedo belogo kar- already in 1868 and continued up to 1886, the first ob- tona" (Determination of the albedo of the white card- server being Per G. Rosén [Fig. 6.7] who made photo- board)]. 63 Figure 6.5: The Round Hall of Pulkovo Observatory (Courtesy of Pulkovo Observatory, St. Petersburg) In the same letter addressed to Berkiewicz Otto ∙ Secondly, Observatory was technically backward Struve had pointed out the meteors – the “shooting” as compared with observatories in Europe and the stars – as the worthwhile objects to be observed in United States of America.