T he O b serv er 's H a n d b o o k FOR 1941 PUBLISHED BY The Royal Astronomical Society of Canada C. A. CHANT, E d ito r F. S. HOGG, A ssistant Editor DAVID DUNLAP OBSERVATORY THIRTY-THIRD YEAR OF PUBLICATION TORONTO 198 C o l l e g e S t r e e t P r i n t e d f o r t h e S o c ie t y By t h e U n i v e r s i t y o f T o r o n t o P r e s s 1941 JULIAN DAY CALENDAR, 1941 J.D. 2,400,000 plus the following: Jan. 1......... 29996 May 1......... 30116 Sept. 1......... 30239 Feb. 1 30027 June 1......... 30147 Oct. 1 30269 Mar. 1 30055 July 1......... 30177 Nov. 1 . 30300 Apr. 1......... 30086 Aug. 1......... .30208 Dec. 1.......... 30330 The Julian Day commences at noon. Thus J.D. 2,429,996.0=Jan. 1.5 G.C.T. T h e O b ser v er 's H a n d b o o k FOR 1941 PUBLISHED BY The Royal Astronomical Society of Canada C. A. CHANT, E d ito r F. S. HOGG, A ssistant Editor DAVID DUNLAP OBSERVATORY THIRTY-THIRD YEAR OF PUBLICATION TORONTO 198 C o l l e g e S t r e e t P r in t e d fo r t h e S o c ie t y By t h e U n iv e r s it y o f T o r o n t o P r e s s 1941 CONTENTS PAGE Preface 3 Anniversaries and Festivals - - - - 3 Symbols and Abbreviations - - - 4 The Constellations - - - - 5 Miscellaneous Astronomical Data - - - 6 Ephemeris of the Sun - - - - 7 Solar and Sidereal Time - - - - 8 Map of Standard Time Zones - - - 9 Times of Sunrise and Sunset - - - 10 Times of Beginning and Ending of Twilight - - 17 The Planets for 1940 - - - - - 18 Eclipses, 1940 - - - - - - 25 The Sky and Astronomical Phenomena Month by Month - 26 Phenomena of Jupiter’s Satellites - - - 50 Phenomena of Saturn’s Satellites - - - 52 Lunar Occultations - - - - 52 Meteors or Shooting Stars - - - 54 Principal Elements of the Solar System - - 56 Satellites of the Solar System - - - - 57 Double and Multiple Stars, with a short list - 58 Variable Stars, with a short list - - - - 60 Distances of the Stars, with a list of the Sun’s Neighbours - 62 The Brightest Stars, their magnitudes, types, proper motions, distances and radial velocities - - - 64 Star Clusters and Nebulae, with Messier’s List - 72 Four Circular Star Maps - - - - - 75 List of Air Navigation Stars - - - 79 Tables of Meteorological Data - - - 80 PRINTED IN CANADA PREFACE The H a n d b o o k for 1941, which is the thirty-third issue, is arranged similarly to that of last year. The chief changes are: (1) The ephemerides of the bright asteroids have been omitted; (2) A list of stars used in air naviga­ tion has been added. The small star maps at the back necessarily contain only a few objects. Four similar maps 9 inches in diameter are obtainable from the Director of University Extension, University of Toronto, for one cent each. Observers desiring fuller information are recommended to obtain Norton’s Star Atlas and Reference Handbook (Gall and Inglis, price 12s 6d; supplied also by Eastern Science Supply Co., Boston, Mass.). The sixth edition contains late information. For the preparation of the material in the volume Dr. F. S. Hogg, Assistant Editor, is largely responsible; but hearty thanks are due to all the staff of the David Dunlap Observatory for their assistance. C. A. C h a n t . David Dunlap Observatory, Richmond Hill, Ont., December 1940. ANNIVERSARIES AND FESTIVALS 1941 New Year’s D ay.............Wed. Jan. 1 Dominion D ay...............Tue. Jul. 1 Epiphany........................Mon. Jan. 6 Birthday of Queen Elizabeth Septuagesima Sunday...............Feb. 9 (1900)............................Mon. Aug. 4 Quinquagesima (Shrove Labour Day....................Mon. Sep. 1 Sunday) ....................... Feb. 23 Hebrew New Year (Rosh Ash Wednesday......................... Feb. 26 Hashanah)................... Mon. Sep. 22 St. David....................... Sat. Mar. 1 St. Michael (Michaelmas St. Patrick....................... Mon. Mar. 17 Day).............................Mon. s 29 Palm Sunday..............................Apr. 6 All Saints’ D ay.............. Sat. Nov. 1 Easter S unday ............................ Apr 1 Remembrance Day.... Tue. Nov. 11 St. George.. Wed. Apr. 23 St. Andrew. Sun. Nov. 30 Rogation Sunday.......................May 18 First Sunday in Advent.. ... Nov. 30 Ascension D ay.............. Thu. May 22 Ascension of King George VI Empire Day (Victoria )............. ec. D ay)....................... .... Sat. May 24 Birthday of King George VI Birthday of the Queen Mother, ) ................................R Dec. 14 Mary (1867)................Mon. May 26 Christmas..D ay...............Thu. Dec. 25 Pentecost (Whit Sunday)— .Jun. 1 Trinity Sunday.......................... Jun. 8 Corpus Christi ...Thu. Jun. 12 St. John Baptist (Midsummer Thanksgiving Day, date set by D ay) Tue. Jun. 24 Proclamation SYMBOLS AND ABBREVIATIONS SIGNS OF THE ZODIAC SUN, MOON AND PLANETS ASPECTS AND ABBREVIATIONS THE GREEK ALPHABET THE CONFIGURATIONS OF JUPITER’S SATELLITES In the Configurations of Jupiter’s Satellites (pages 27, 29, etc.), O represents the disc of the planet, d signifies that the satellite is on the disc, * signifies that the satellite is behind the disc or in the shadow. Configurations are for an inverting telescope. THE CONSTELLATIONS L a t in a n d E n g l is h N a m e s w it h A bbreviations Andromeda, Leo, Lion........................ .Leo Leon (Chained Maiden) ...A n d Andr Leo Minor, Lesser Lion. .LMi LMin Antlia, Air P um p Ant Antl Lepus, Hare................... .Lep Leps Apus, Bird of Paradise.. Aps Apus Libra, Scales.................. Lib Libr Aquarius, Water-bearer. .Aqr Aqar Lupus, Wolf................... Lupi Aquila, Eagle....................Aql Aqil Lynx, L ynx.................... Lync Ara, Altar......................... Ara Arae Lyra, Lyre...................... Lyra Aries, Ram .......................Ari Arie Mensa, Table (Mountain)Men Mens Auriga, (Charioteer). .Aur Auri Microscopium, Bootes, (Herdsman) . Boo Boot Microscope........... Micr Caelum, Chisel................. Cae Cael Monoceros, Unicorn. Mon Mono Camelopardalis, Giraffe..Cam Caml Musca, F ly.................... Musc Cancer, Crab.................... Cnc Canc Norma, Square.............. Nor Norm Canes Venatici, Octans, Octant............... .Oct Octn Hunting Dogs..............CVn CVen Ophiuchus, Canis Major, Greater Dog.CMa CMaj Serpent-bearer............ Oph Ophi Canis Minor, Lesser Dog.CM i CMin Orion, (Hunter)............ .Ori Orio Capricornus, Sea-goat. .. Cap Capr Pavo, Peacock................ .Pav Pavo Carina, Keel....................Car Cari Pegasus, (Winged Horse) Peg Pegs Cassiopeia, Perseus, (Champion).. Per Pers (Lady in Chair)......... Cas Cass Phoenix, Phoenix.......... Phe Phoe Centaurus, Centaur........Cen Cent Pictor, Painter.............. Pic Pict Cepheus, (K ing)...........Cep Ceph Pisces, Fishes................. Pisc Cetus, Whale.................. Cet Ceti Piscis Australis, Chamaeleon, ChamaeleonCha. Cham Southern Fish............ PsA PscA Circinus, Compasses...... Cir Circ Puppis, Poop................. Pup Pupp Columba, Dove............... Col Colm Pyxis, Compass............. Pyx Pyxi Coma Berenices, Reticulum, Net.............. Ret Reti Berenice's Hair...........Com Coma Sagitta, Arrow.............. Sge Sgte Corona Australis, Sagittarius, Archer....... .Sgr Sgtr Southern Crown.......... CrA CorA Scorpius, Scorpion........ .Scr Scor Corona Borealis, Sculptor, Sculptor......... Scl Scul Northern Crown..........CrB CorB Scutum, Shield.............. .Sct Scut Corvus, Crow..................Crv Corv Serpens, Serpent............ Ser Serp Crater, Cup.....................Crt Crat Sextans, Sextant............ .Sex Sext Crux, (Southern) Cross. .Cru Cruc Taurus, Bull.................. .Tau Taur Cygnus, Swan.................Cyg Cygn Telescopium, Telescope. .Tel Tele Delphinus, Dolphin........Del Dlph Triangulum, Triangle. .Tri Tria Dorado, Swordfish..........Dor Dora Triangulum Australe, Draco, Dragon................Dra Drac Southern Triangle__ TrA TrAu Equuleus, Little Horse... Equ Equl Tucana, Toucan............ .Tuc Tucn Eridanus, River Eridanus. Eri Erid Ursa Major, Greater Bear. UMa UMaj Fornax, Furnace.............For Forn Ursa Minor, Lesser Bear.UMi UMin Gemini, Twins................Gem Gemi Vela, Sails...................... Vel Velr Grus, Crane.....................Gru Grus Virgo, Virgin................. Vir Virg Hercules, Volans, Flying Fish. Vol Voln (Kneeling Giant)........Her Herc Vulpecula, Fox.............. Vul Vulp Horologium, Clock..........Hor Horo Hydra, Water-snake.......Hya Hyda The 4-letter abbreviations are in- Hydrus, Sea-serpent.......Hyi Hydi tended to be used in cases where a Indus, Indian..................Ind Indi maximum saving of space is not Lacerta, Lizard...............Lac Lacr necessary. 5 MISCELLANEOUS ASTRONOMICAL DATA U n i t s o f L e n g t h 1 Angstrom unit = 10-8 cm. 1 micron = 10-4 cm. 1 meter = 102 cm. = 3.28084 feet 1 kilometer = 105 cm. = 0.62137 miles 1 mile = 1.60935X105 cm. = 1.60935 km. 1 astronomical unit = 1.49504 X1013 cm. = 92,897,416 miles 1 light year = 9.463 X1017 cm. = 5.880 X1012 miles =0.3069 parsecs 1 parsec = 30.84 X1017 cm. = 19.16 X1012 miles =3.259 l.y. 1 megaparsec = 30.84X1022 cm. = 19.16 X1018 miles =3.259 X106 l.y. U n i t s o f T i m e Sidereal day = 23h 56m 04.09s of mean solar time Mean solar day = 24h 03m 56.56s of sidereal time Synodical month = 29d 12h 44m; sidereal month = 27d 07h 43m Tropical year (ordinary) =365d 05h 48m 46s Sidereal year =365d 06h 09m 10s Eclipse year =346d 14h 53m T h e E a r t h Equatorial radius, a = 3963.35 miles; flattening, c = (a —b)/a =1/297.0 Polar radius, b = 3950.01 miles 1° of latitude = 69.057 —0.349 cos 2φ miles (at latitude 0) 1° of longitude = 69.232 cos φ —0.0584 cos 3φ miles Mass of earth = 6.6 X1021 tons; velocity of escape from O =6.94 miles/sec. E a r t h ’s O r b i t a l M o t i o n Solar parallax = 8."80; constant of aberration = 20."47 Annual general precession = 50."26; obliquity of ecliptic = 23° 26' 50" (1939) Orbital velocity = 18.5 miles/sec.; parabolic velocity at O = 26.2 miles/sec.