the OBSERVER’S HANDBOOK 1975 sixty-seventh year of publication the ROYAL ASTRONOMICAL SOCIETY of CANADA editor: JOHN R. PERCY THE ROYAL ASTRONOMICAL SOCIETY OF CANADA Incorporated 1890 Federally Incorporated 1968 The National Office of the Society is located at 252 College Street, Toronto 130, Ontario; the business office, reading room and astronomical library are housed here. Membership is open to anyone interested in astronomy and applicants may affiliate with one of the eighteen Centres across Canada established in St. John’s, Halifax, Quebec, Montreal, Ottawa, Kingston, Hamilton, Niagara Falls, London, Windsor, Winnipeg, Saskatoon, Edmonton, Calgary, Vancouver, Victoria and Toronto, or join the National Society direct. Publications of the Society are free to members, and include the Journal (6 issues per year) and the Observer’s Handbook (published annually in November). Annual fees of $12.50 ($7.50 for full-time students) are payable October 1 and include the publications for the following calendar year. PRINTED IN CANADA BY THE UNIVERSITY OF TORONTO PRESS the OBSERVER’S HANDBOOK 1975 sixty-seventh year of publication the ROYAL ASTRONOMICAL SOCIETY of CANADA 252 College Street, Toronto M5T 1R7, Canada editor: JOHN R. PERCY INDEX PAGE Anniversaries and F e stiv a ls..........................................................................................3 Asteroids—Ephemerides at Opposition................................................................52,71 C lusters...........................................................................................................................98 C o m e ts...........................................................................................................................76 Constellations................................................................................................................. 5 Eclipses................................................................................................................ 40,57 G a l a x i e s ................................................................................................................... 102 Impact Craters...............................................................................................................77 Julian Day Calendar................................................................................................... 11 Jupiter—Belts and Z o n es............................................................................................. 50 —Longitude of Central M e r id ia n ................................................................73 —Phenomena of S atellites ............................................................................74 Mars—Longitude of Central M eridian......................................................................70 —M ap .....................................................................................................................54 Messier’s C a ta lo g u e ................................................................................................... 97 Meteors, Fireballs and M e te o rite s............................................................................76 Miscellaneous Astronomical D a t a ..............................................................................6 Moon—O b serv atio n................................................................................................... 58 —M a p ...............................................................................................................69 Moonrise and M o o n s e t............................................................................................. 22 Nebulae—G a l a c t i c ................................................................................................. 100 Occultations—L u n a r ................................................................................................... 59 —G r a z i n g ............................................................................................. 66 —Planetary, A p p u lses............................................................................57 Planets—G e n e ra l.........................................................................................................28 —Elements........................................................................................................... 8 Precession for 50 Y e a r s ............................................................................................. 79 Radio Sources............................................................................................................. 101 Satellites of Solar System............................................................................................... 9 Saturn—S atellites.........................................................................................................78 Sky and Astronomical Phenomena Month by M o n t h ........................................ 32 Solar System—E lem en ts............................................................................................... 8 —List of S atellites................................................................................... 9 Star M a p s ................................................................................................................... 104 Stars—B rightest.........................................................................................................81 —Double and M ultiple....................................................................................... 96 —Names, Finding L is t ....................................................................................... 80 —N earest...............................................................................................................92y —V a r i a b l e .............................................................................................. 48,9^ Sun—E p h e m e ris ...........................................................................................................7 —Physical O bservations....................................................................................... 56 —Sun-spot C y c le ................................................................................................... 28 Sunrise and S u n s e t ................................................................................................... 15 Symbols and A bbreviations......................................................................................... 4 Time—Correction to S u n - d ia l ................................................................................... 7 —Radio Time S ig n a ls ........................................................................................11 —Solar, Sidereal, Universal, Standard, Ephemeris ....... 10 —Map of Time Z o n e s ........................................................................................12 Twilight...........................................................................................................................21 Visiting Hours at Observatories, P l a n e t a r i a ..........................................................13 THE OBSERVER’S HANDBOOK 1975 THE o bserver’s h a n d b o o k for 1975 is the sixty-seventh edition. I wish to thank all those who assisted in its preparation: those whose names appear in the various sec­ tions, those mentioned below, and especially my editorial assistant John F. A. Perkins. There has been some rearrangement of material in this issue; both new readers and readers of past issues should skim through and find out “where everything is” . Also in this issue, metric units have been introduced wherever possible. There is a new section on “Impact Craters”, so that readers can find their way to visit some of these spectacular features. The h a n d b o o k is continually being expanded and improved. This year, I extend a warm welcome to three new contributors—P. Blyth Robertson, who pre­ pared the section on impact craters, Brian G. Marsden, who supplied the material on periodic comets, and Janet Mattei, who as the new Director of the A.A.V.S.O. supplied the predictions of Algol and of other variable stars. At the same time, I want to take this opportunity to thank Margaret W. Mayall who before her retire­ ment as Director of the A.A.V.S.O. supplied these predictions for many years. Once again, special thanks go to Leslie V. Morrison and Gordon E. Taylor, H.M. Nautical Almanac Office, for the predictions of total and grazing lunar occul- tations and of planetary appulses and occultations; to Maude Towne and Isabel Williamson for the tables of moonrise and moonset; to the David Dunlap Observa­ tory and Erindale College, University of Toronto, for financial, technical and moral support. Finally, my deep indebtedness to H.M. Nautical Almanac Office and to the American Ephemeris is gratefully acknowledged. Jo h n R . P er c y ANNIVERSARIES AND FESTIVALS, 1975 New Year’s Day........... Wed. Jan. 1 Victoria Day................. .Mon. May 19 Epiphany....................... Mon. Jan. 6 Trinity Sunday.............. May 25 Septuagesima Sunday. Jan. 26 Corpus Christi.............. Thur. May 29 Accession of Queen St. John Baptist Elizabeth (1952) Thur. Feb. 6 (Mid-Summer Day).. .Tues. June 24 Quinquagesima Dominion Day.............. .Tues. July 1 (Shrove) Sunday....... Feb. 9 Birthday of Queen Mother Ash Wednesday............ Feb. 12 Elizabeth (1900) .Mon. Aug. 4 St. David....................... .Sat. Mar. 1 Labour Day.................. .Mon.