" J Winter Solstice 1975 No. 10

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Canadian A's.tronomical ,S_OC,.....· ~~u..:.I ; " "' " '' • u ' ¢ ~ Societe Canadienne d'Astronomie;'\ Cassiopeia

------. ------. ------______0 No. 10 Winter Solstice Issue 1975

CANADIAN ASTRONOMICAL SOCIETY

SOCIETE CANADIENNE D'ASTRONOMIE

Editor: Dr. John F. Heard,

As soc. Editor: Dr. David L. DuPuy , st . Maryi s University

1976 June Institute

The Universi ty of TorontoQs Department of Astronomy and the will host the 1976 June Institute on Tuesday, June 8 to Friday, June 11 , inclusive. All are cordially invited to attend . Details of the programme are not yet final , but will be announced i n the Vernal Equinox issue of CASSIOPEIA. For more information, write to Dr. John R. Percy, Department of Astronomy, University of Toronto, Toronto , Ontario M5S lA7 0

t h DEADLINE for the Vernal Equinox i ssue of CASSIOPEIA is March 10 , Please send material to David L, DuPuy, Department of Astronomy, Saint MaryQ s University, Halifax, Nova Scoti a B3H 3C3. 2 NOTES FROM UNIVERSITIES

UNIVERSITY OF TORON TO

Vis i tors to the Observatory

Visi t ors who have recently given colloquia on Camp u s o r a t th e Observatory are:

Pierre Demarq ue of Yale on "Carbon Abund a nces in Horizo n tal Branch Stars". Amos Ya hil of Princet o n on "Bi g Bang Nucleosynthesis". Sandra Fabe r of Lick on "Elliptical Galaxies: Velocity Dispersions , In tern a l Dynam i cs, Gas Content". Gust av Tamma n, Hal e Ob s ., "Distances of Galaxie s in the Loca l Supercl uster". Donald Morton of Princeton on "M ass Loss from Stars". David Strangway, Geo l ogy, U. of T., o n "A Model for Lunar Evolution". Rog e r Bell, U. of Md ., "The Chemical Composition of Globula r Cluster Stars". Robert Kraft of Lic k on "The Origin and Evol ution of RR Lyra e Stars of Hig h Metal Ab undance ".

Staff and Student Note s

Phil ipp Kr on berg , on sabbatical l eave a t Bonn thi s session, paid a flying vi sit t o Toronto and to Green Bank in mid - November . He is enjoyin g his work at Bon n a nd hi s wife and child r e n a re rap i d ly learning German (in whic h Phil ipp is fluent) .

Radio and TV h ave been calling on us a goo d deal this past a ut umn. For a series entitled "Ideas" o n CBC fm John Lomberg, a To ron to a rti st and ga laxy "fre ak " conceived and wrote an eight -week seri es e ntitled "Into the Unive rs e"; Tom Bolton , Bob Garrison and Sidney van den Bergh took part. Bob Ga rrison app eared t wice on Global TV and on Ontario Educati o nal TV du r i n g October a nd had weekly talk s wit h Jud y La Marsh on her CBC morn i n g rad io sh ow during November and December . Rene Ra cine has been a re gu l a r gues t every ot her Frid ay morning a t 8:3 0 on CJBC (French language radio) , s peaking for 5 to 7 minutes on "Chronique d' Astronomie". This has been going on fo r about tw o years . Next tra nsm issions J a n . 2 , Jan . 16 . J Don MacRae was at DAD Dec . 13-14 , alo n g with othe r members of th e CF HT Boa rd, inspect i n g th e present state of th e 142 -inch blank . Then they went to th e Institute of As tronomy, Uni versity of Hawaii for Board and Committee meet in gs Dec. 1 5 -1 8, and on Dec. 19 they asce nded Ma un a Kea t o see the construction which has taken place there over th e past year an d a half.

Bob McLaren who has rec e ntl y been appointed to th e teac h ing staff in Astro n omy (joint l y with Physics) h as now taken up his duties. Bob's speci a lty has been infrared astronomy.

Re n ~ Racine recentl y visited t he University of Regina as a memb er of a n ad hoc adviso r y commi tt ee to th e Faculty of Graduate St u dies a nd Researc h and also visited The University of Montreal fo r discussions of their observatory project.

Helen Hogg a ttended the AAVS O Annual meeting Oct. 17 -19 at Co n cord Mas s ., a nd was a gues t of President Car l Williams of UWO for luncheon on Nov. lIon the occasion of the ope nin g th e re of th e Exhibit of the work of 19 Ca n adian Women Scientists.

During the week of Oct. 22-29, Bob Garrison was in France attending a CFHT Spectrograph Working Group meetin g at Haute Proven ce , a nd Ren~ Racine a l so visited Haute Provence and attende d a Scientific Advisory Co mmittee Meeting o f CFHT a t Meudon.

S i dney van de n Be rgh spoke on "Galaxy Evolution a n d Classification" at Rice Un iversity , Hous t on on Sept . 25, a t th e New York Astronomical Societ y meeti n g in Alban y on Nov. 1, t o the M. I. T. Ce n tre for Space Science on Nov . 1 8 and to the Yale Astronomy Depar tment on Nov . 20. He observed variable s t ars i n nearb y galaxies and supernovae remnant s with the 48-inch Schmidt tel escop e at Palomar on Nov. 2-9. At that time h e observed tha t (his) cornet 1974g was about t wo magnitudes bright er th a n pr edic t ed , at B ~ 17 .

Torn Bo lton a ttended t he Goddard Symposi um on X- Ray Binaries at the Goddard Space Centre in Greenbe lt, Md. Oct . 20-22, chairing a session o n Cy gnus X-I and g iving two papers.

Bob Garrison was in Chicago for th e A.A . S. meeting Dec . 8-10 and then went to Las Campanas for an observing session until Jan . 6 . Others a tt e nding the A.A.S . meeting were Sidney vdB , Christine a nd Ma uri ce Clement and Ernie Seaq u ist .

Receivin g de grees i n astronomy at the fall Convo cation were Ted Bednarek and Chris Pritche t (Ph. D.). and Richard Gr ay ) Martine Normandin a nd Gilles M~nard (M . Sc.) . Lrauuute student S t eve Shore attenueu the 1.I\ . U. Colloquium on I\p stars in Vi enna Sept. 7-12. Steve authored or co-authoreu four of the papers, presenting three of t h em himse l f. Other Canadians at t ending the Colloquium inc l uded R i l l !\' e h 1 au, C h r i s /\ i k ma n and J 0 h n Lan u s t r e e t ,

University of Western Ontario

At the fall co"vocation Louis Fortier and Arno Krautter r eceived their M.Sc. degrees . Loui s is spendi ng a year in Europe while Arno is working for Ameli a Wehlau and Serge Demers of Lauren­ tian.

The department has rented the i ce in the university's neW arena for a weekly hockey game, hel d each Thursday morning. The two teams are made up impartially from a selection of undergraduates, graduate students and faculty. Black eyes and sore muscles have also been distributed impartia lly.

Mike Marlborough presented a review paper on "Model s for the Circumstellar Envelopes of Be Stars" at I AU Sympo s ium No. 70 , "The Merrill-McLaughlin Symposium on Be and Shell Stars", held a t Cape Cod , l'1assachusetts, September 15-19. Graduate students Henry Lepar­ skas, Roland Poeckert and Ian Thompson a lso attended; Roland presented a paper on "Intrinsi c Linear ? olarization of Be Stars as a Function of V sin i."

Bill Wehlau attended a series of CFHT meetings in Pa ris and at Haute Provence Observatory during the las t two weeks of October, as well as a meeting of the CFHT board in Hawaii in mid-December.

Dave Gray gave a colloquium at the University of Texas entitled "Turbulence Measurements and Other Interesting Applications of Li ne Profiles." He was also in Texas to use the 107-inch telescope , collecting data pertaining to turbulence in the s olar photosphere .

Saint MaryUs University

The Depar tment of Astr onomy has an opening for a post-doctoral fellow, to begin March 1 , 1976, or earlier. For details, contact the CAS/SCA Employment Committee, or the University. RLSLAR C' H NL (US

Th e IlDO Ilicrodcnsitollletcr

by

Tom Bo I t on

!\ Ligh speed no l I er and Chi ven s PhotoTTict ric !Jut;] Syst ems llI i c r Ci­ densitometer 1,,15 install ed at t he David Dun l ap Oh servatory ill late Jul y , 1974. After an extended shakedol,·n pel·ioc!, r equirec to repa ir dama ge incurred in sh ipm ent, it hecame operation,ll in ~Iar c h, 1975. Since that tim e , it has provjded an enormous stimu l u~ to the spectrogrGphic research progTGm 5 unden'!;!), Gt \lUO. Since pu rt of the r at ionale for obtainil~g thi s machine was that it he made avai l ah l e for the usc of Canudi all astronomers in genera l, I ~ould like briefly to describe the hardh'are and soft l~arc current l y available a nd some of the cClpub ilities of the system. Visitors ' use of the system i s welcome and a num ber of visit ing investigator s have already ava iled them­ se lves of th e opportun ity to li se the ma chine. Anyone I'l ho ha s

The FDS 1l1icrodensitometer is <1 very high speed scanning syc;tem. It can scan at any r3te up to 60,000 microns per second taking data at intervals as sm~ll as 1 micron. The scan rate, scan pa ttern, and data interval are computer cont ro lled. The s tage has a 10 x 10 inch scanning ar ea but larger Flates can he accommodated. Positions are r ead Ollt t o the neare s t micron by the usc of linear optical encoders on both the \ - and Y- axes. The man ufacture r s pecifics r ead-out a ccuracy of " :': I mic ron per mi llime t er, not to exceed ± 3 microns i n the total s t age travel", and repeat3bility of ± 1 micron. Our tests indicate that ollr mac hine exceeds these specifications . The photometric amplifier is sensitive from 0.0 - 4 . 0 in density when us ing a 100 square micron saElp l ing aperture . It is linC'iH to t 0.02 dens ity and stable to the same limit over 10-hour ]leriods after a 45-minute harm-li p.

The com puter control is carried out by a J1fW s/r comput er with 16 K core l ocati ons . Peripherals include a high-speed parer - tape r eader/pullch, O[C\\'H ITrR , 2

Our early software development has concentrated on imp r oving the manufacturer ' s scanning program (Alex lIay ) and deve l oping a package of prog nms for spectrographic analysis (Alan Irwin and Austin Glliliver) The spectrographic analysis package can produce norma lized, rectified intensity vs. wavelengt11 tracings from density versus position data . An optional noise filtering r outine is included . A portion of the spectrographic analysis package can be used separately t o produce 11igh qua lity radial­ ve locity measurements from the scan data. Another package permits the add ition or subtraction of spectral scans . A program to calcul ate equivalent widths for specific Jines in the scans is now being prepared. Some preliminary work has begun on n package of two dimensional analysis programs . These wi ll eventually include programs to do photographic , isophotometry and astrometry.

We already have one hardware modification underway. A new plAte holder is under construction to replace the g l ass platen supp lied by the manufacturer . The removal of the g lass platen from the analyzing beam should yield a substantial decrease in the scattered light and greatly improve the photometric accuracy. A number of improvements to the system are available - such as a photog raphic playback system, 0-5 photometric system, interactive CRT, ro l l film attachment - and we hope to be able to slowly upgrade the system in the future.

Ancillary TnstrllmE2..J1t ation for the CFfl-Te l escope

Re n~ Racine

This is a short description of the initial instrumentation to 11e provided f or the Canada-France-llawaii 3.6 m telescope . It is present ed at this time for t he information of the Canadian astronomical community h'hile there sti 11 is time left for modifications or adeli tions. 1'\o ne of the instruments have yet reached the cons truction phase but detailed studies have begun on many of them. I t is expected that calls for tenders for t he realization of these instrument s will be sent by the ~, !eudon PI' oj ect Office (P . O. ) CR. Cayrel, G. Odgers) eluring the first half of 1976. Groups and individuals should forward t heir comments or requests ei ther to P. Charvin (chairman) or W. Wehlau (vice-chairman) of the Scientific Adv isory Council (SAC) and should let the P. O. know of their event ual interest in bidding for the construction of specific instruments.

Table 1 lists all the equipment currently proposed

Instrumentatiun for the CFli Te lescope

Instruments Responsibi lity Status Cash ($K)

1. Adaptor-Cui der-TV W1erick, Racine, Vin Ll (350)

2. Correctors fi.acinc, Wlerick, D (160) Wynne

.) . DAIC Walker, Bourlon c 280

4. Detectors (harvin, Stockton, A-C 300 Walker, Labeyrie

5. Photography Racine D 150 fl. Plate Meas. Engines Wlerick, Racine A 160

7 . Photoelec. Photom. Racine, f'hanes lJ 160 ---- 8. Filter Polarimeter Ra c ine, Land s treet, D 50 1'-lartin

9. Polariz. t-Jodulator Racine, Borra c 30

10. IR-Upper end Cruikshank c 110 lla. IR Photometer Cruikshank, Clarke, A-C 100 lIb. IR Spectrometer ~!aill ard

12. Fabry-Perrot Georgel i n_ C 40

13. Spectrograph I Wehlau, Crampton, D 250 Richardson, Garrison

14. Spectrograph II Wehlau , Baranne, D 550 Wlerick, Georgelin

15. Spectrograph I II Wehlau, Richardson, C 500 Crampton

16. Supplemental Spectro. Wehlau, Crampton, A-C 350 Georgelin

17. Lab. Equipment S .A.C. C-D 250

TOTAL $3.28~J + ( ~O.51M) Croup (We) clwj I'lIlCn ;lr(' under! incd. They s hould he cont;lcted for detai l ed j nLluiries. The present SUltus of the ins t rum{;nt i s gj ven as : 1\: accepted by SAC, B: no design studies made; C: conceptual design comp l ete ; LJ: de tai l ed spccificDtions comp l eted, ready for-call for tenders . lite estimated cost s given in the Li s t column range in character from weJ I -docllme nted figures to "educated guesses" . Costs in par enthesis arc assigned to the Telescope Budget, others to Instrument

The general philosophy behind this "shopping list" prep3 r ed by the SAC in collaboration with the various WG's is to provide a complem ent of general purpose ins truments \vhich are users -oriented and should not no rmally require development of new technology for their realization or extensive training of tIle observer s for their operation. Most instruments will be remote-controllable and will interface to the Data AC~lisi tion s and II1 strument Con t rol (DAIC) computers. Manual operations of the key functions will also be possible as a help in setting up and debugging the instrument and as a redundant system. Short notes on each instrument fo l low.

1. Adaptor-Guider-TVSystems

Oetailed studies of the Cassegrain unit are well advanced . At the prime focus mo st of the fU1lctions will be incorporated in the instruments themselves . These adaptors provide wide ( ~ 10') field TV viewing (diagonal mirror) and small ( ~ 2 ' ) field viewinr, of the star image (reflected from slit jaws, photometer aperture, etc) . Programable off-sets and off- axis automatic guiding (quadrant detectors) will be included as well as visual centering and guiding. At least one side port fed by a diagonal flat with a 10' field will be available at the Cassegrain adaptor to permit quick interchange bet ween spectroscopy or photometry and photography . Another import ant function of these adaptors is to provide rotation of the instrument packages about the optic axis .

2 . Correctors

A large triplet corrector designed by Wynne for the prime focus (scale: lS" / mm) will gjve a 1° flat field on a 10" x 10" p late at F/3 . 8. Sma ller field (~ 20') doublet correctors optimized f or the UV and near-lR are also planned at this f ocus. At the F/B Cassegrain focus (scale 7~2/mm) doublet corrector s will give a 27' flat field. All correctors are r emovab l e.

3. Data Acquisition and Instrument Control (OAlC)

CPU mainframes will be Hewlett-Packard 2lMX series minicomputers (same model as for Telescope Control System (TCS)) with disks and tape peripherals, fast line printer and punched tape units , graphic display and keyboard consoles with VOU' s . CAMAC interfaces and associates modules have been opted for. Close cooperation with the Project Office (P. Sourlon) is 9 required to ensure compa tibility of instruments control l ers il nd data lines with the DAIC. A second sys tem pJrallel Gme! identicul to the IlAIe will ex i s t to llermit the t esting of equipment before install a tion on the t cl escope and as kick-up l!nits for the DA IC or the TCS them sel ves . Although DMA cap:lbiliti es and benchmark performances of the lIP ma inframe are s li gh tly inferior to thosc of "hotter" commercial machines , manu fac turers reputation and, mo s tly, guarant eed r e lia bility of the mainframe and periphera l S at high altitude \V ere decisive in the se l ection of this syst em. It is not yet certa i n that other groups on ~ I a una Ke a (NASA, U.K .) will make the same choice .

4. Detectors

State-of-the-ar t detectors are to be provided for use at most instrumen t s. First and foremost will be the "cameras e lectronographique s de La llemand" (W l erick) but some difficulties ar e foreseen i n the ir use in an "upside-down" configuration at the prime f ocus. Two - dimensional pulse­ counting detectors using I-SIT or channel plates vidicons (Labeyrie) or I -CCD ' s (Wa lker) ar e also planned. A 256 x 256 CCD system i s currently being developed at UBC. Stockton is in charge of converters and intens i fiers . Detai l ed studies of a t wo-stage, optically-coupled RCA tube and of a singl e­ stage, 90 - mm f ibre op tics coupled ITT intensifier are unden,a), .

5. Photogr aphic Cameras

A conventional camera similar to the KPNO-CTIO 4-m. prime -focus camera will be useable for wide- fie ld work at both the prime and cassegrain foci . I t wi ll incor porat e a spot-s ensitometer and its own automat ic guider since vignetting problePls \Vi II prevent the use of the adaptor's guider . Sma ller plate holders or jmage-tube holders \ViII be provided for the auxilIary cassegrain par t es).

6. Plate-Measuring Engines

This is still an ill-defined catego r y and its shopping lis t includ es SUC!l items as l ight tabl es , microscopes and a PDS (?) micro­ densitometer for evaluati on of electronographic p l ates.

7 . Photoelectric Photometer

A sing l e universal photometer useable at both foci is proposed. It consist s of a photomet er head including viewing opt ics (eyepiece and TV), calibrat ion sources , filter, diaphragm and chopper wheels. Inter­ changeable cold-boxes will attach to t he he ad. Single or dual beam modes are possible in either a one- or two-photomultipliers configuration. Onl y one colour is mea sured at a time. Photocathodes ' responses range from S4 (lP2l ) through Sll, S20, S25 to III-V (RCA-3l034A) for a total of e l even cold-boxes. Da ta acquisition will be by pulse counting modu l es . 10

~. l-'i Iter l'uLlri llleter

/\ specia l -purpose Stoke-meter (linear ;lnd c ircular po lari za tion). Thi s rotatabl e instrument uses a Pock e ls ce ll modillator . It u ~es the photometer he:ld, to which it i.s attached, and the pUlse-counting electronics of the ph otometer. Co ntinuulll and line work \"i II be possible using variable­ ti lt interference filter . The instrument proposed is s imilar to those usee! by Landstreet and Martin at KPNO and ~1cDonald .

0. PoLtrization Modulator

Thi s narrow ( ~ ~') field modul ator also llses a Pockels cell and can he i.nstalled ahead of the focal plane for direct two dimentiona l polarimetry or ill front of a slit for spectro-polarimetry. This is simi lar to the 200-inch arrangement used by Borra and Land street with Oke ' s scanner.

10. Infrared Upper End

Thi s special -purpose low-emissivity telescope upper-end "a l a Ricke and Low" will contain <1 sub-diameter (zero field) rocking secondary glvlng an F/35 Cassegrain beam. Detailed design will be done in consultation Kith the group responsible for the NASA IR-telescope on I- launa Kca.

lla. IR Photometer

To be used in conjunction with the IR upper-end this broad-band photometer will contain up to three dewar-detectors for simu ltaneous or quick-beam swit ching work from 1)1 to 350)1. Doped Ge crystals, PbS and In Sb detectors will be provided . A proposal for a liquid-helium-cooled, mu lti ­ element IR spectrum scanner of intermediate resolution has also been received.

lIb. IR CFT?) Spectrometers

Numerous proposals for moderate-to-very-high-resolution IR spectrometers have been received by the SAC. It is still unc l ear which configuration and spectral coverage will be adopted but very high resolution instruments for the I-to-lO-micron range arc currently being studied.

12. Fabry-Perrot [tal ons

The very successful nebular studies by the /,larsei lIe group (Court~ s , Georgelin, Cruvelier) makes this a natural instrument for the CFHT . The actual configuration is still to be defined but will probably lise a real-time 2-D pulse- counting detector. 11 1:< . Spectrograph I ("UV and Quasar s")

This is a modular spectrograph for use at the Cassegrain and prime focu s and designed along the lines of the DAO 72- i nch instrument. Throughput and wide spect r al r ange will be max imi zed for faint stellar work from the UV to the near IR. Dispersions will range from about 300 o 0 A/mm t o about ::'0 A/mm. Conv entional short slits and image - s hcer s will be used. Fast cat adioptric and folded Schmidt cameras (aspherized gr at ings are also contemp l at ed) wi l l have sufficient back-foca l distances to accommoda t e image intensifiers as we ll as photographic plates.

14. Spectrograph I I (" Ne bular")

This is a massive Cassegrain spectrograph of the "pupille blanche" design with very l ong s lits (7' or 60 mm), 20 cm gr atings and e lectronographic cameras as detectors , although plates and intens ifiers will a lso be used. Intended especial l y for nebular work, this i nstrument is now being studied in detail by Baranne and the Marseill e group .

I S. Spect rograph II I (coude)

Des i gned along the lines of the DAO interchangeable small-mir ror coud~ this will be fed by an F/ 160 beam transformed to F/20 before the s lit or s licer . The vastness of the two coude rooms (65-ft diam.) and of Harvey Richardson ' s imagination (-) _, ) r enders the possibilities staggering . As a first priorit y a 20 -c:w-grating system with a Schmidt camera giving di spersions of about 5 A/mm an d a very-high-dispersi on F/20 camera for use wi th detect or arr ays are being planned.

16 . Supplemental Spect rosc~ic Equipment

This ill -defined category comprises : more cameras, different spectral ranges, mor e gr atings (including l arge mosaics), eche lle and eche l ette systems f or Cassegrain and coud~ spectrographs , and a photo­ e lectric line scanner of high resolution .

17. Laborat ory Equipment

Th is inc ludes : cryogenics, liquifiers , dewars, st andard calibration sources , monochromators, sensit ometers, preparation rooms and equipment for e l ectronographic cameras , photographic mat erial preparation (evacuat ion , bak ing , hypersensiti zing) and processing, optical testing l abs , electronic supplies and t est equ ipment. 12

COile III s i OI~

Th e latest P[ IZT eh agr8m of the proj ect (No v . 19 75) sh ows the fo ll o~ing comm issioning dat es:

Prime Focus: Nov 19 70 Cass o Focus: Mar. 1979 Coude Focus: May 1979 (comp l etion date)

Since the origi li al completion date established in I:eb . 19 7.7) was Jan . 1979 it is cl ear that the Project Office has done a super b job of keeping the s lippag e down to 4 months in two years . It i s 81so clear that to a l ar ge ex t ent the ti me scal e for the realization of the i ns tru­ mentat ion \,'ill dictate wh en the CFlI -tel escope will begin to yi eld its first scientific results.

Frequency Allocations for Radi o Astronomy

Preparations have begun in Canada for a World Administrative Radio Conference in 1979 . These conferences are hel d under the auspices of the Internationa l TeJec ommunications Union with the pur­ pose of amending , as required, the Radio Regulations which govern t he international use of the radio s pectrum. Among the vari ous services to which spectrum space is allocated , radio astronomy i s t he mos t suscep­ t ible to radio interference. Radio astronomers need to be continually vigilant to ensure that existing a llocations are not withdrawn or are not damaged by all ocati or.s to other services i n the same or adj acent frequency bands.

The 1979 Conference will be the first conference since 1959 where all ocati ons to all se~v ic es are open to examination and possible amendment . It will be the first confer ence since 1971 where changes to r adio astronomy a llocations may be made. Since 1971 radio astronomy has seen major improvements i n sensiti vity, and increased use of fre­ quencies above 10 GH z. The i mportance of spectral line observations which wa s developing during preparation for the 1971 Conference i s now very evident . The growing use of satellites for communication a nd earth and atmospheric s ensing is an i nterference thr eat from whi ch the most remote observatory cannot escape. Thes e items, and others , need to be examined in preparati on for the 1979 Conference .

A government committee has been established to prepare a Canadian position for the 1979 Conference. As NRC represenative I have some responsibility for seei ng that a ll scienti fic uses of radio are given consideration in preparing the Canadian position. In additi on Gilles Beaudet and Don MacRae have asked me to represent the CAS and Associate Committee on As tronomy in this work . I would be pleased to hear from any astronomer with views on the matter of frequency allocati on or with a concern for a specific interference probl em. Although the Conference i s more than three years away it i s important to present views early before firm positions are adopted .

Lorne Doherty Herzberg Institute of Astrophysi cs 1J D01'1TNION i\ STROP lI YS TCi\ L ()BS I':J{ ')i\,[,() I{Y

During the pas t f ew months t h e re lwve b een seve r :J l visitors. Dr. T. R. Stoeckley of Mi chigan State V. ,grrived c.l rly in Sl'p t cmbe r to !~p(' nd a sabbat i cal year as Gu es t Inve stigator to s t udy slelLlr rOLll i on and soon afterwards Dr. S. Ru c inski a rrive d from Wa r saw <1S o ur fir s t R(>sc:J r ch i\ssoc Llt e to work wi t- h ol.\r gr oup on close bina ry stars . Relatively brief vis i ts h;lve b een made by Dr. Anne Cowley of Mi ch igan a nd Dr. Geraldine Peters of V.C . I. . A. to use o ur ARCTURU S measuring machine , whil e Dr. J. Andersen dropped in fo r a few days on hIs wa y back to Copenhagen f r om Chil e . Dr . A. S,gnyal comple t ed his work on e Lyrae and Nova Cygni 1975 ilt the end of November and lef t for a year a t Iowa Sta t e U. Dr. Grah:J m Hill retllrned from St . Andrews a t the e nd of the summe r and left a lmos t i mme diately to observe stars ne ar the south galactic pole at Cerro Tololo ; he obta ined 300 spectra and made 1200 photometric HS observations. Chris Aikma n ob served 35 nights at Las Campanas using the Ric hardson spectr ograph on t he Toronto 24-inch telescope to obtain 700 spec t ra of 150 othe r so uth galac tic pole s t ars . Hill and R. W. Hilditch (S t . Andrews) have completed several papers on star s near the north gal act' c pole. Dr . Dave Cramp t on and Dr. Harvey Richardson spent a week at Mar seille \-lith the CFH. s p ec trograph working group and the Scientific Advisory Council. Gr a ham Odgers was home f or couple of weeks in Sep t embe r and a t t he begLnning of December t o confer with the staff on our cont ribut i ons to the CFH telescope. Sever al membe rs of the CFH Board of Directors also visited the Observatory o n December 13 on their way to a Hawaii board mee ting .

Roy Dan c ey r e 00rts that the 3.6 m mirr or blank is progressing satisfactorily. The prirl:ary has been fine ground to spheri cal form and has r e ceived a n initial i"h>lishing of abol t 12 hours duration to enable optical tests t o b e !,crfo:::-n:ed. On Decemb2r 1, 1975 the first knife- edge and e qual plate i n!: ' ~rfe ru1Deter t ests we r e made and the follow ing results ob tained. Th(-: radius of curvature was measured at t~~ metres whic h is within, but near the top of, the initial f igurin g . 10 tolerance (27.10 metres m axi~um) . This number will shorten toward the mean as the asphe r ic correcti on is a p plied. The mirror figure fits the bes t sphere within 2 wavelengths a s determined by the interferome ter , with astigmatism 2. 1 wCi velcI1gth which will be removed during the figur ing and aspherizing process. Knife e dge t es t s s how the mirro r form to be a fairly smooth slight aspheric, as expected, wi t h the centre of curvature blur circle due to this me asured at 0.4 mrn or 3 arc seconds . The mirror was then given an add itional 15 hours po lishing s o that the above resul ts can be confirmed by square screen Ha r tmann t es ting f o llowed b y t he COITUnencemen t o f cor r ection and figuring in January as scheduled .

The 48" mirror for the Hindle testing of the E',ecundary has been completed , and t he 73 11 spherical mirror for the complemen t a ry Richardson tes t is in the grinding process . De s i gn of t he tool ing for the secondary itself will be gin in Janua ry so that it will be ready for use when the 73" mirro r is completed .

K.O .\.]. 14

It's Good t o be Back

For t he sake of astronomy and to have a bit of advent -Jre , I accepted in 1974 an invitation to spend my sabbatical year at the University of Chile in Santiago. Astronomers understand why someone wants to go to Chil e , but our neighbours who had never heard of the clear skies of the "Norte Chico" thought that we were out of our minds. To go to Chile at a time when the neWs media reported mostly terribl e stories was considered q~ite amazing.

A stay at the University of Chile offered not only the accessi­ bility to modern observatories , but also close contact with graduate students, non- existant at Laurenti an . Thanks to a NRC travel fellow­ ship, my Wife, our two children and I hopped into a plane on a sunny day of May , along with two trunks and nine suitcases .

Even though Carmen and I spoke Spanish and were familiar wi th Chile , it was still fairly complicated to relocate our family i n Santiago . The search for a house was , as expected , not too diffi cult because at that time nuny Chileans wer e leaving the country. However , most of them wa nted one year's rent in advance. And the car was with­ out doubt the biggest headache. He considered it out of the question to bring our own car, since ~ uch a car could not have been serviced in Chile, a license plate i n Santiago would have cost nearly $1000 , and we would have been without the car for at least four months, taking into account the return trip ,

We fiw~lly settled in a completely furnished house, ten minutes from Cerro Calan Obse:,:,vatory. We were fortunate to find a good maid. While driving a tiny ten year old rented car I dreamed of a hugh s tati on wagon .

During the first few JTlonths I prepared a graduate course on variable s tars which was givE.;D twice during my stay a t the Univer s i ty of Chi le. My trtps t o the observatories started in the spring of 1974 , and I travelled at least a dozen times to La Serena during the year in Chile .

From the astronomical point of view, my sabbatical was a success . Most of my research projects were done in collaboration wi th Bill Kunkel of Cerro Tololo. We obtained phot ometric data and C-M diagrams for the Reticulum cluster and the Sculptor and Fornax dwarf elliptical galaxies . I had the chance to observe during several nights with the new 4-meter telescope. We also started a photographic survey of the dwarf irregular gala,xies near the (e. g . Sextans , GR8 , Wolf-Lundmark-Melotte object, etc.). We have photoelectric s equences for most of them. During two observing sessions with the 60 -cm tele­ scope of the University of Toronto at Las Campanas, I collected a l arge amount of data on globul ar cluster variables. Amelia Wehlau is collaborating in these projects also . 15

Certainly the greatest moment of my sabbati cal occured in June 1975, one month before returning home! While investigating the connection between the newly-discovered cluster in Reticulum, the LMC and the Magellanic stream, Bill Kunkel and I discovered that eight stellar systems lie in a plane passing by the galactic center and the two Magellanic Clouds. We believe that this Magellani c Plane defines the orbital plane of the LMG around our Galaxy. The stellar systems lying i n the plane are t idal remnants l ost by the LMC . This idea and its implications could not be full y developed at that time because I had to r eturn to Canada. Our colla bora tion is now more difficult, but not at a ll i mpossible.

By July a ll the f a mily Was fed up with a t hird winter in 18 months. The kids had missed thei r friends and Were anxious to go back home. Our "adventure" ended up with a sour note . We discovered at the travel agent that our children, who had been residents of Chile for more than one yea r (Carmen and I had go ne to Cordoba), had to pay , like all Chileans, a travel tax of $250' each in order to leave Chile to go to Canada. (This law was changed on November 1, 1975.) We had to spend a weekend in Mendoza before leaving Chile for Canada .

In retrospect, a year spent in Chile on our own , was certainly quite an experience. This i s an experience We will never repeat! After several years of political unrest , 1974-75 Were years of reconstruction for Chile, plagued with a yearly infl ation of 4O'OIs and economic problems barely conceivable for Canadians.

Serge Demers Institute for Astronomy Laurentian University

CA S/SCA Employment Committee

The CAS/SCA Employment Committee i s asking all prospective employers and all job candidates to register with the Committee. All candidates are a sked to submit a neW registration form, to bring the Committee ' s records up to date. Please use the format as shown on page 6 of the Hinter Solstice No . 6 issue of Cassiopeia. Send these forms to CAS/SCA Employment Committee Dr. Ri chard Bochonko Astronomy, University Coll ege University of Mani toba Winnipeg, Manitoba R3T 2M8