ASTRONOMICAL
HANDBOOK FOR
SOUTHERN AFRIC
1 990
published by the Astronomical Society of Southern Africa
ISSN 0571-7191 ASTRONOMICAL HANDBOOK FOR SOUTHERN AFRICA 1990
This booklet is intended both as an introduction to observational astronomy for the interested layman - even if his interest is only a passing one - and as a handbook for the established amateur or professional astronomer.
Front cover The exibition of amateur made astronomical equipment at the astronomy week held jointly by Planatariura of the South African Museum and the Cape Center in September 1989. Photograph courtesy of Mr J Joubert.
(5)the Astronomical Society of Southern Africa, Cape Town. 1989 CONTENTS
ASTRONOMY IN SOUTHERN A F R I C A ...... 1 DIARY ...... 4 THE S U N ...... 6 THE MOON. . . ,...... 8 COMPUTING AND SOLAR SECTIONS...... 14 THE PLANETS...... 15 THE MOONS OF JUPITER ...... 22 THE MOONS OF SATURN...... 26 COMETS AND M E T EORS...... 27 OCCULTATIONS BY MINOR PLANETS...... 29 THE S TARS...... 30 ORDINARY OCCULTATIONS...... 36 GRAZING OCCULTATIONS...... 40 TIME SYSTEMS AND TELESCOPE SETTING...... 45 ASSA OFFICE BEARERS...... 47 JULIAN D A T E S ...... 49
NOTE
All times are SAST unless otherwise stated.Right Ascension and Declination are given for equinox of date unless otherwise stated.
This handbook is produced for the Astronomical Society of Southern Africa. The data it contains has been adapted for Southern Africa from data obtained from the Royal Greenwich Observatory, Herstmonceux, from the British Astronomical Association, the International Lunar Occultation Centre,Tokyo and the Hydrographer of the South African Navy.
Assistance in the compilation of this booklet was received from the Directors of the observing sections of the ASSA and Mrs. P. Kramer.
All correspondence concerning this booklet should be addressed to the Handbook Editor, Astronomical Society of Southern Africa, 10 Bristol Rd., Observatory, 7925 from whom further copies are available at R5,00 per copy.
Although every care has been taken in the compilation of the Handbook.it is sold and distributed on the explicit understanding that neither the Society nor its members accept any responsibility for errors therein.
Dit spyt ons dat as gevolg van beperkte fondse en produksie fasiliteite dit nie moontlik is om die handboek in Afrikaans te laat druk nie.
P .J .Booth Editor ASTRONOMY TISJ SOUT1IJLCR1ST A FR I CJA
As one of the few parts of the Earth having both access to the rich southern skies and a suitable climate, Southern Africa holds a favoured position in astronomy. Consequently, it has seen the establishment of a number of professional observatories engaged in research while many individuals have become enthusiastic amateur astronomers. Planetaria and visiting nights at observatories convey to the general public much of what goes on in this field.
OBSERVATORIES The South African Astronomical Observatory (SAAO) was established in 1972, as a joint venture between the Council for Scientific and Industrial Research (CSIR) of SA and the Science Research Council of the UK,combining the facilities of the former Royal and Republic Observatories, and is directed by Prof M W Feast. On the closure of the Radcliffe Observatory in 1974,the CSIR acquired the 1.9-m telescope, and moved it to Sutherland in the Karoo, where there are also 1.0-m, 0.75-ra and 0.5-m telescopes. The headquarters in Cape Town also carrys out a limited amount of observing. Research is undertaken in many areas, with considerable effort being put into the study of variable stars, the Galactic Centre, the Magellanic Clouds and sources detected by satellites. These studies involve the use of spectroscopic, photometric and infrared techniques. Besides providing research facilities for its own staff, SAAO observing time is allocated to astronomers from South African universities and elsewhere in the world. Boyden Observatory, situated at Mazelspoort, 25 km from Bloemfontein, is owned by the Institute and Dept of Astronomy of the University of the Orange Free State. Observing facilities include a 1.52-ra and two 0.41-m telescopes, as well as the 0.25-m Metcalf camera, a 0.33-m refractor and a 0.20-ra solar installation. The main research areas include flare stars, short period variable stars, and atomic emissions from nebulae, the Sun and interplanetary space. The Hartebeesthoek Radio Astronomy Observatory, 30 km NW of Krugersdorp, is a national facility managed by the Foundation for Research Development. The Director is Dr G D Nicolson. The 26 ra telescope operates at 18, 13, 6, 3.6 and 2.5 cm wavelengths and is used for observations of interstellar and circumstellar molecules, pulsars, x-ray sources as well as quasars and active galaxies. The observatory provides research facilities for astronomers in South African universities as well as its own staff and frequently collaborates in global networks of telescopes using the technique of very long baseline interferometry. In addition to the professional observatories mentioned above, South Africa and Zimbabwe have numerous private observatories,built and operated by amateur astronomers.
OBSERVATORIES OPEN TO THE PUBLIC SAAO headquarters in Observatory, Cape Town is open to visitors on the second Saturday of each month at 20h00. It is not necessary to make a booking, unless there are more than ten persons in a party. Day visits are possible to the SAAO observing site near Sutherland, and enquiries should be made to Sutherland prior to the intended visit. Enquiries as to visiting nights at Boyden Observatory, Bloemfontein should be made to the Observatory.
PLANETARIA A planetarium is located within the South African Museum in Cape Town. This new planetarium, containing a Minolta Series 4 projector and seating 120, represents one of the most advanced of its kind in the world today. A planetarium is situated in the grounds of the University of the Witwatersrand in Johannesburg (entrance in Yale Road, alongside the Ml). It is equipped with a Zeiss projector and seats over 400 persons. Regular shows are given at both of these planetaria, from which details may be obtained. 2
UNIVERSITIES Several universities undertake research in astronomy and offer teaching courses. The chair of astronomy at UCT is occupied by Brian Warner, whose department uses the SAAO observing facilities at Sutherland. The Dept of Applied Mathematics, UCT has a group carrying out research in theoretical cosmology lead by Profs G F R Ellis and D R Matravers. The University of OFS has an Institute (created in 1981) and a Dept of Astronomy. Both are incorporated with the Boyden Observatory. The Dept of Physics and Electronics at Rhodes University, under Prof E E Baart, specialises in radio astronomy, and has its own observatory outside Grahamstown. The Dept of Mathematics, Applied Mathematics and Astronomy at. UN1SA offers a number of courses in astronomy and astrophysics. Prof W F Wargau is the head of Astronomy at UNISA.
THE ASTRONOMICAL SOCIETY OF SOUTHERN AFRICA The Astronomical Society of Southern Africa is a body consisting of both amateur and professional astronomers. Membership is open to all interested persons, regardless of knowledge or experience. In addition to this Handbook, the Society issues the "Monthly Notes of the Astronomical Society of Southern Africa" (MNASSA). Members also receive the popular monthly magazine "Sky and Telescope" published in the USA, which provides information on professional and amateur activities, together with news of space research and other related subjects. The Society's annual subscription is R75.00 and there is an entrance fee of RIO,00. A prospectus and application form may be obtained from the Honorary Secretary, Astronomical Society of S A, c/o S A Astronomical Observatory, P 0 Box 9, Observatory 7935, Cape.
LOCAL CENTRES OF THE SOCIETY Autonomous local centres of the Society hold regular meetings in Cape Town, Durban, Johannesburg, Bloemfontein, Pietermaritzburg, Pretoria and Harare.Visitors are very welcome at meetings and may, if they wish, join a Centre without becoming a full member of the Society. Centre members receive neither Society publications, nor "Sky and Telescope". 3
CAPE CENTRE (Cape Town): Formal meetings are held on the second Wednesday of the month (except in January and December) when professional and prominent local amateur astronomers present lectures on the latest topics in Astronomy. Informal meetings are held on most other Wednesdays except during January and December. At these informal meetings discussion groups and observing sessions are held. Two or three out.-of-town weekend observing sessions are held annually in areas where dark skies are available. The Centre publishes a quarterly journal, the "Cape Observer" which gives information on meetings, current activities and objects to observe. Further information may be obtained from the Secretary, P.O.Box 13018, Mowbray, 770b, telephone (021) 543028. Meetings are held at. the SAAO, Observatory Road. Observatory at 20h00.
TRANSVAAL CENTRE (Johannesburg): General meetings are held on the second Wednesday of each month, excluding December, in the Sir Herbert Baker building in the grounds of the former Republic Observatory, 18A Gill Street, Observatory, Johannesburg at 20h00. The meetings consist, of lectures, films or observing evenings. There are two small observatories on the site. One contains the Jacobs telescope, a 30cm F8 Newtonian and in the Papadopoulos Dome is housed a combined instrument comprising a 18cm F16 refractor, a 15cm refractor and a 30cm F16 Cassegrain reflector. Informal observing evenings are held every Friday night. The Centre publishes a monthly newsletter "Canopus”, which carries information on meetings and the Centre's activities. Secretarial address: P 0 Box 93143, Yeoville 2143, telephone (Oil) 9461998.
NATAL CENTRE (Durban): Regular monthly meetings are held at 19h45 on the second Wednesday of each month at Marist Brothers School, South Ridge Road, Durban. The Centre publishes a monthly magazine "Ndaba" which contains news and views and current information on astronomical and relaLed topics. Secretarial address P 0 Box 5330, Durban, 4000, telephone 031-(W) 867091 (H) 255979/823316/844751 and Fax no (031) 844392.
NATAL MIDLANDS CENTRE (Pietermaritzburg): Regular monthly meetings on the second Wednesday of each month (except January) at the PMB Music College, Havelock Road at 19h45. information on meetings and membership is available from the Secretary Mr J Watson, P 0 Box 2106, Pietermaritzburg, 3200 or by phoning 0331-33710 or 33646.
BLOEMFONTEIN CENTRE: Meetings are held every fourth Friday of the month. For information contact Miss L E Stone. 17 La Quellerie, Pres. Paul Kruger Avenue, Bloemfontein, 9301.
PRETORIA CENTRE: Meetings are held on the fourth Wednesday of each month (except December) at 19h00 at the Christian Brothers' College, Silverton Road, where the Centre's observatory containing a 30cm reflecting telescope is situated. For further information contact the Secretary Mr N Young at 201 Kritzinger St., Meyers Park, Pretoria. 0184 telephone 012-833765.
HARARE CENTRE: The Centre holds a meeting on the last Wednesday of each month (except December). These are usually held at 17h30 at the Queen Victoria Museum and consist of lectures, films or general discussions. Informal observing sessions are also hejd at the homes of members. Secretarial address P 0 Box UA 428, Union Avenue, Harare. Zimbabwe.
OBSERVING SECTIONS OF THE SOCIETY These sections exist to co-ordinate constructive observing prograforaes. Mention of the type of observations and equipment involved are made in the appropriate parts of this handbook together with the names and addresses of the directors. Computing Section see page 14 Solar Observing Section see page 14 Comets and Meteors see page 2? Minor Planet Occultations see page 29 Occul Lai: ions see page 36 Grazing Occultations see page 40 Nova Search Section see page 35 Variable Stars see page 34 4
DIARY OR PHENOMENA , 1 9 5iO CONFIGURATIONS OF SUN , MOON AND PI.ANF.TS
d h d h Jan 2 20 Neptune in conjunction with Sun Mar 28 10 Noon at perigee 4 13 FIRST QUARTER 30 9 Venus greatest elong. H. (46*) 4 19 Earth at perihelion 6 23 Saturn in conjunction vith Sun Apr 1 20 Jupiter 3* S. of Moon 7 21 Noon at perigee 2 12 FIRST QUARTER 9 4 Mercury in inferior conjunction 10 5 FULL MOON 9 10 Ceres O'.6 S. of Moon 12 22 Noon at apogee 10 2 Jupiter 4‘ S. of Noon 13 17 Nercury greatest elong. E. (20') 11 7 POLL NOON 14 1 Uranus stationary 13 23 Mercury 3' K. of Neptune 14 9 Antares O'.l S. of Noon 18 23 LIST QUARTER 16 13 Neptune stationary 19 1 Venus in inferior conjunction 16 21 Uranus 3' N. of Noon 19 18 Noon at apogee 17 6 Neptune 3’ N. Of Moon 20 5 Kercury stationary 18 3 Saturn l'.$ N. of Noon 22 10 Antares o ‘.3 N. of Noon Occn. 18 9 LAST QUARTER 23 17 Hars 4' N. of Noon 20 22 Mars 3'S. of Noon 24 15 Uranus 3‘_N. of Noon 22 3 Venus 4' S. of Moon 24 22 Mercury 5' N. of Noon 23 17 Kercury stationary 25 1 Neptune 4’ N. of Noon 25 6 NIK MOON 25 12 Saturn 3' N. of Noon 25 19 Moon at perigee 26 21 MEN NOON , 29 10 Jupiter 3’ S. of Moon 28 1 Mercury 0".8 K. of Neptune May 1 22 FIRST QUARTER Feb 1 3 Mercury greatest elong. 54.(25*) 4 2 Nercury in inferior conjunction 2 5 Noon at perigee 5 4 Saturn stationary 2 21 FIRST QUARTER 7 7 Pluto at opposition 3 17 Nercury o'.2 N. of Saturn 8 5 Juno at opposition 4 8 Mercury^ 7’ S. of Venus 9 22 FULL MOON 5 12 Ceres o'.3 N. of Noon Occn. 10 2 Moon at apogee 6 6 Jupiter 4’ S. of Noon 11 15 Antares 0 .2 S. of Moon 6 12 Ceres stationary 14 2 Uranus 2' N. of Noon 7 7 Venus 7' N, of Saturn 14 12 Neptune 3' N. of Noon 3 6 Venus stationary 15 10 Saturn 1'.5 N. of Noon 9 16 Kars o'.2 S. of Uranus 16 9 Mercury stationary 9 21 FULL NOON Eclipse 17 22 LAST QUARTER 14 19 Venus 7' N. of Saturn 19 22 Kars 6\s. of Moon 16 15 Moon at apogee 21 22 Venus 7' S. of Moon 17 3 Mars l ’.5 S. of Neptune 23 5 Nercury 9' S. of Noon 17 21 LAST QUARTER 24 5 Moon at perigee 18 18 Antares 0 ‘.3 N. of Moon 24 14 NEK MOON 21 2 Uranus 3' N. of Moon 25 13 Pallas in conjunction with Sun 21 12 Neptune 4' N. of Moon 27 4 Jupiter 2' S. of Moon 21 18 Mars 2' N. of Moon 31 5 Kercury greatest elong. W. (25') 22 2 Saturn 3' N. of Moon 31 10 FIRST QUARTER 22 6 Venus 8' N. of Noon 22 15 Venus greatest brilliancy Jun 6 6 Moon at apogee 23 3 Piuto stationary 7 21 Antares 0 .2 S. of Moon 24 3 Nercury 2' S. of Noon 8 13 FULL NOON 24 21 Jupiter stationary 10 7 Uranus 2‘ N. of Moon 25 11 NEW NOON 10 17 Neptune 3' N. of Noon 28 10 Noon at perigee 11 14 Saturn 1 .4 N. of Moon 28 19 Mars l'.O S. of Saturn 16 7 LAST QUARTER 17 18 Hars 7’ S. of Moon Mar 4 4 FIRST QUARTER 18 4 Mercury 4' N. of Aldebaran 4 22 Ceres l’.i N. of Moon 20 13 Venus 7' S. of Moon 5 11 Jupiter 4' S. of Noon 21 13 Moon at perigee 11 13 FULL NOON 21 18 Solstice 12 16 Vesta in conjunction ïith Sun 22 21 NEW NOON 16 10 Noon at apogee 24 0 Jupiter l'.6 S. of Noon 16 19 Juno stationary 29 17 Uranus at opposition 18 2 Antares O'.2 N. of Moon 30 0 FIRST QUARTER 19 17 LAST QUARTER 20 3 Mercury in superior counjunction Jul 2 19 Nercury in superior conjunction 20 13 Uranus 3 N. of Noon 3 17 Venus 4' N. of Aldebaran 20 22 Neptune 4' N. of Noon 3 18 Moon at apogee 20 23 Equinox 4 7 Earth at aphelion 21 16 Saturn 2' N. of Noon 5 4 Antares O'.2 S. of Noon 22 20 Mars O'.4 S. of Moon 5 13 Neptune at opposition 23 9 Venus 2' N. of Noon 7 11 Uranus 2' N. of Moon 26 22 NEK NOON 7 18 Juno stationary 5
DIARY OF PHENOMENA, 1 9 9 0 CONFIGURATIONS OF SUN,MOON AND PLANETS
d h d h Jul 7 22 Neptune 3* N. of Hoon 8 3 FULL (tOON Oct 4 14 FULL HOON 8 16 Saturn 1*.5 K. of Hoon 6 20 Hoon at perigee 14 20 Saturn at opposition' 8 21 Hars 5' S. of Hoon 15 8 Jupiter in conjunction with Sun 11 6 LIST QUIETER 15 13 LIST QUIRTEE 12 22 Jupiter l'.O N. of Hoon 16 10 Ears 8' S. of Noon 18 18 NEW HOON 19 13 Moon at perigee 20 14 Hars stationary 20 5 Venus 4’ S. of Hoon 22 6 Hercury in superior conjunction 22 5 HEW HOOK , 22 10 intares O ’.6 S. of Hoon 23 20 Hercury 3) H. of Hoon 22 18 Hoon at apogee 29 8 Hercury 0".04 H. of Regulus 24 17 Uranus l ’.9 N. of Hoon 29 16 FIRST QUIETER 25 4 Neptune 3* N. of Hoon 31 4 Pluto stationary 25 19 Saturn l ’.l N. of Hoon 31 10 Hoon at apogee 26 22 FIRST QUIETER lug 1 11 Intares O ’.l S. of Hoon Nov 1 17 Venus in superior conjunction 3 16 Uranus 2’^N. of Hoon 3 0 FULL HOON 4 4 Heptune 3’ H. of Hoon 4 1 Hoon at perigee 4 20 Saturn l ’.6 H. of Hoon 5 4 Hars 3’ S. of Hoon 6 16 FULL HOON Eclipse 9 9 Jupiter l ’.t N. of Hoon 9 7 Venus 7' S. of Pollux 9 15 LIST QU1RTER 11 22 Hercury>greatest elong. E. (27*) 10 11 Pluto in conjunction with Sun 13 1 Venus 0*.04 N. of Jupiter 13 12 Hars 6* N. of Ildebaran 13 18 LIST QUIETER 15 22 Vesta at opposition 13 21 Hars 7* S. of Hoon 17 5 Hercury 3‘ N. of Intares 15 12 Hoon at perigee 17 11 NEW HOON , 18 15 Jupiter^O"^ S. of Hoon 18 17 intares O'.7 S. of Hoon 19 2 Venus O ’.5 H. of Hoon 18 22 Hercury l'.7 N. of Hoon 20 15 NEW HOON 19 5 Hoon at apogee 20 18 Ceres in conjunction with Sun 20 6 Hars closest approach 22 14 Hercury O ’.2 N. of Hoon Occn. 21 1 Uranus 1 .6 N. of Hoon 25 2 Hercury stationary 21 12 Neptune 2’ N. of Hoon 28 5 Hoon at apogee 22 6 Saturn O ’.6 N. of Hoon 28 10 FIRST QUIETER 25 15 FIRST QUIETER 28 19 intares O ’.2 S. of Hoon Occn. 27 23 Hars at opposition 30 23 Uranus 2’N. of Hoon 30 15 Jupiter stationary 31 11 Neptune 3' N. of Hoon Dec 2 1 Hars 3’ S. of Hoon Sep 1 2 Saturn l’.7 N. of Hoon 2 10 FULL HOON 5 4 FULL HOON 2 13 Hoon at perigee 6 23 Venus O'.8 N. of Regulus 6 9 Hercury greatest elong. E. (21' 8 6 Hercury in inferior conjunction 6 18 Jupiter 2' N. of Hoon 9 13 Hoon at perigee 9 4 LIST QUIETER 11 1 Hars 6' S. of Hoon 10 10 Hercury l'.3 S. of Uranus 11 23 LIST QUIETER 10 13 Juno in conjunction with Sun 14 17 Hercury 3' S. of Venus 14 20 Hercury stationary 14 21 Uranus stationary 15 23 Intares O'.7 S. of Hoon 15 8 Jupiter 0 .3 N. or Hoon 16 6 Hoon at apogee 16 18 Hercury stationary 17 6 NEW HOON 17 22 Hercury 2' N. of Hoon 18 7 Hercury 0 ’.6 N. of Uranus 19 3 NEW HOON 18 20 Neptune 2' N. of Hoon 23 5 Saturn stationary 19 1 Hercury 1'.4 H. of Venus 23 9 Eguinox 19 12 Venus O'.6 S. of Uranus 23 18 Neptune stationary 19 17 Saturn O ’.2 N. of Hoon Occn. 24 6 Hercury greatest elong. W.(18 ) 22 5 Solstice 25 0 Hoon at apogee 23 5 Venus l ’.8 S. of Neptune 25 3 Intares 0 .4 S. of Hoon 24 10 Hercury in inferior conjunction 25 9 Hars 4' N. of ildebaran 25 5 FIRST QUIETER 27 4 FIRST QUIETER 29 3 Hars 2 S. of Hoon 27 8 Uranus 2‘N. of Hoon 31 2 Hoon at perigee 27 20 Neptune 3' N. of Hoon 31 18 Uranus in conjunction with Sun 28 10 Saturn 1'.5 N. of Hoon 31 21 FULL NOON 28 10 Vesta stationary 6
THE SUN
BASIC DATA: Diameter: 1 392 000 km (109 times Earth diameter)
Mass: 1,99 x 10 ^kg' (330 000 times Earth mass)
Surface Temperature: Approximately 6 000°C
Temperature at centre: Approximately 10 million°C
The Sun is our nearest star. It is composed chiefly of hydrogen and is in a gaseous state throughout. So hot and dense is its interior that nuclear reactions occur there - thus producing the energy that is eventually radiated from its surface. At times its surface is disturbed by sunspots (which may persist for some weeks) and short-lived flares.
The Earth's orbit round the Sun is not quite circular. In 1990 we will be closest to the Sun on January 4 (perihelion - approximate distance 147 million km) and furthest from the Sun on July 4 (aphelion - approximately 152 million km). During the year, the Sun appears to us to make a complete circuit of the sky (i.e. relative to the starry background) as indicated in the diagram*. Sumer Solstice
Permanent damage to the eye can be caused by looking directly at the Sun. The diagram below shows how a small telescope (or half a binocular) may be used to project an image of the solar disc onto a piece of white card. It may also be advisable to stop down the telescope aperture so that the eyepiece is not damaged by the intense light passing through it. Tiny black sunspots are generally visible on the otherwise white solar disc - if monitored over a period of a week or so. the rotation of the Sun should be apparent.
—— C»nJbo*rd Light Shield ___ WhU®White C»rCard Eveolece - * Sunlight D ~ T~T>^ r: i P L . , . , , Teleacop*Tele-cope Ad)u«tAd>u«l Focve
THE SUN'S DECLINATION AT 02 HOURS:
Jan 1 23 ‘'03'' S Apr i i 8'’08'’N Jul 20 20'’45'N Oct 28 12'‘58''S U 21 53 s 21 11 42 N 30 18 38 N Nov 7 16 08 s 21 20 00 s May 1 14 56 N Aug 9 16 00 N 17 18 52 s 31 17 31 s 11 17 45 N 19 12 56 N 27 21 02 s Feb 10 14 30 s 21 2Q 05 N 29 9 32 N Dec 7 22 33 s 20 11 05 s 31 21 51 N Sep 8 5 52 N 17 23 20 s Mar 2 7 23 s Jun 10 22 59 N 18 2 03 N 27 23 21 s 12 3 31 s 20 23 26 N 28 1 50 S 31 23 08 s 22 0 26 N 30 23 12 N Oct 8 5 42 S Apr 1 4 21 N Jul 10 22 18 N 18 9 27 s TIMES OF SUNRISE AND SUNSET FOR THE MAIN CITIES OF SOUTHERN AFRICA
CAPETOWN DURBAN BLOEMFONTEIN JOHANNESBURG HARARE sunrise sunset sunrise sunset sunrise sunset sunrise sunset sunrise sunset h m h m h ID h IB h ra h m h m h m h IB h m Jan 1 05 38 20 01 04 58 19 01 05 21 19 18 05 18 19 04 05 24 18 35 11 05 46 20 02 05 06 19 02 05 79 19 18 05 25 19 05 05 29 18 37 21 05 55 19 59 05 14 19 00 05 37 19 17 05 33 19 04 05 37 18 38
Feb 1 06 07 19 52 05 24 18 55 05 46 19 13 05 42 19 00 05 42 18 36 11 06 1/ 19 44 05 32 18 48 05 54 19 06 05 49 18 55 05 47 18 32 21 06 26 19 33 05 41 18 39 06 02 18 57 05 54 18 47 05 52 18 27
Mar 1 06 33 19 23 05 46 18 30 06 08 18 48 06 00 18 39 05 55 18 21 11 06 41 19 11 05 53 18 19 06 13 18 38 06 04 18 29 05 57 18 15 21 06 49 18 58 05 59 18 06 06 18 18 27 06 11 18 19 06 00 18 06
Apr 1 06 58 18 41 06 06 17 53 06 25 18 13 06 17 18 06 06 02 17 57 11 07 04 18 30 06 11 17 43 06 30 18 03 06 21 17 56 06 04 17 50 21 07 13 18 17 06 17 17 31 06 35 17 52 06 25 17 47 06 07 17 43
May 1 07 20 18 06 06 24 17 22 06 42 17 44 06 31 17 38 06 10 17 37 11 07 28 17 57 06 31 17 14 06 49 17 36 06 37 17 31 06 13 17 32 21 07 34 17 50 06 36 17 06 06 54 17 30 06 41 17 26 06 16 17 29
Jun 1 07 43 17 45 06 43 17 04 07 01 17 27 06 47 17 23 06 20 17 28 11 07 48 17 44 06 48 17 03 07 05 17 26 06 52 17 22 06 23 17 27 21 07 51 17 44 06 51 17 04 07 06 17 27 06 55 17 24 06 26 17 29
Jul 1 07 53 17 48 06 53 17 07 07 10 ) 7 30 06 57 17 27 06 27 17 32 11 07 51 17 52 06 51 17 11 07 06 17 34 06 55 17 30 06 27 17 35 21 07 47 17 58 06 48 17 16 07 05 17 39 06 53 17 35 06 26 17 40
Aug 1 07 39 18 06 06 42 17 22 07 00 17 45 06 48 17 41 06 23 17 42 11 07 30 18 13 06 34 17 29 06 53 17 51 06 41 17 46 06 18 17 46 21 07 19 18 20 06 24 17 35 06 42 17 55 06 32 17 50 06 11 17 48
Sep 1 07 06 18 27 06 12 17 40 06 31 18 01 06 21 17 54 06 04 17 49 11 06 52 18 34 06 00 17 46 06 19 18 06 06 11 17 59 05 55 17 51 21 06 38 18 41 05 48 17 51 06 07 18 10 05 59 18 03 05 46 17 52
Oct 1 06 25 18 48 05 37 17 57 05 57 18 16 05 50 18 08 05 39 17 54 11 06 12 18 55 05 25 18 03 05 45 18 22 05 39 18 12 05 30 17 57 21 05 58 19 04 05 12 18 09 05 33 18 27 05 27 18 17 05 23 17 59
Nov 1 05 46 19 13 05 02 18 17 05 24 18 35 05 19 18 24 05 16 18 03 11 05 38 19 23 04 55 18 26 05 17 18 44 05 13 18 32 05 14 18 08 21 05 31 19 33 04 49 18 34 05 12 18 52 05 06 18 39 05 11 18 13
Dec 1 05 29 19 43 04 48 18 42 05 11 19 00 05 07 18 46 05 12 18 19 11 05 28 19 50 04 48 18 50 05 11 19 07 05 08 18 53 05 14 18 25 21 05 32 19 57 04 52 18 57 05 15 19 14 05 12 19 00 05 18 18 31
ECLIPSES OF THE SUN The annular eclipse of January 26 and the total eclipse of July 22 are not visible from Southern Africa. B
The Moon
BASIC DATA Diameter: 3 480 km (0,27 of Earth) Mass: 7,35 x 10 2 x kg (1/81 of Earth) Surface Gravity: 0,16 of Earth Average distance from Earth: 384 000 km
THE SURFACE OF THE MOON In common with the bodies of our solar system, the Moon's surface suffered bombardment by numerous minor bodies during the period 4,5 to 3,0 billion years ago. This has produced the heavily cratered topography now visible. Some particularly large impacts, caused large circular depressions, which were flooded by molten lava from the Moon's interior. These are the maria basins which appear smoother and darker then the rest of the surface (the latin words mare and maria come from older times when the basins were mistaken for seas). The maria surfaces being younger have fewer large craters, but the entire surface is peppered with tiny craters produced by tiny bodies which have also served to plough up the ground thus forming the regolith - a layer of loose material a metre or so deep.
THE MOON'S ORBIT As a result of its motion around the Earth the Moon appears to make a complete circuit of the heavens in just under a month MOON The Moon's orbit around the Earth is slightly elliptical; the Earth is SCALE DRAWING situated at one of the foci of the / ellipse. Thus the Earth-Moon distance Perigee > varies slightly during the course of a revolution. Dates of Apogee, when the » EARTH moon is furthest from the Earth / Apogee (approximately 407 000 kra) and of Perigee, when the Moon is closest to the Earth \ / (approximately 357 000 km) are given on the next page. "..... ’* The Moon is best positioned for evening viewing from 3 to 4 days before First Quarter to shortly after Full Moon.
ECLIPSES OF THE MOON The total eclipse of the moon on February 9 will be in progress as the Moon r i ses. The last part of the partial eclipse on August 6 will be visible from the extreme eastern parts of Southern Africa. The eclipse data is as follows: d h m d h IQ Moon enters penumbra Feb 9 18 19.6 Aug 6 13 29.5 Moon enters umbra 19 28.6 14 44.2 Moon enters totality 20 49.2 Middle of the eclipse 21 11.1 16 12.3 Moon leaves totality 21 32.9 Moon leaves umbra 22 53.5 17 40.5 Moon leaves penumbra 10 0 02.6 18 55.1
Contacts of Umbra Position .Angles Contacts of Umbra Position Angles with limb of Moon from the North Point with limb of Moon from the North Point Fi rst 89° .9 to East First 106°.6 to East Last 41° .3 to West Last 151*.5 to West Magnitude of the Eclipse 1.080 Magnitude of the Eclipse 0.682 h m h m Moon rise at Harare 18 24 Durban 17 26 Durban 18 40 Johannesburg 18 47 Bloemfontein 18 58 Port Elizabeth 19 08 Cape Town 19 37 g
TERMINATOR AND LIBRATION During the changing phases,the terminator (the boundary between illuminated and dark portions) progresses from left to right in the diagram on page 10. Since the moon does not follow a perfectly circular orbit and its axis is not parallel to the Earth's axis, it is sometimes possible to see a slightly greater proportion of one limb than the opposite one. This effect is known as libration.
PHASES and VISIBILITY NEW MOON
d h m d h m d h m Jan 26 21 20 May 24 13 47 Sep 19 02 46 Feb 25 10 54 Jun 22 20 55 Oct 18 17 37 Mar 26 21 48 Jul 22 04 54 Nov 17 11 05 Apr 25 06 27 Aug 20 14 39 Dec 17 06 22
SCHEMATIC DIAGRAM OF MOON'S ORBIT FIRST QUARTER
d h m d h ra Jan 4 12 40 Jan 18 23 17 Feb 2 20 32 Feb 17 20 48 Mar 4 04 05 Mar 19 16 30 Apr 2 12 24 Apr 18 09 02 May 1 22 18 May 17 21 45 May 31 10 11 Jun 16 06 48 Jun 30 00 07 Jul 15 13 04 Jul 29 16 01 Aug 13 17 54 Aug 28 09 34 Sep 11 22 53 Sep 27 04 06 Oct 11 05 31 Oct 26 22 26 Nov 9 15 02 Nov 25 15 11 Dec 9 04 04 Dec 25 05 16
FULL MOON
d h m d h m d h ra Jan 11 06 57 Jun 8 13 01 Nov 2 23 48 Feb 9 21 16 Jul 8 03 23 Dec 2 09 50 Mar 11 12 58 Aug 6 16 19 31 20 35 Apr 10 05 18 Sep 5 03 46 May 9 21 31 Oct 4 14 02
MOON at 1PERIGEE MOON at APOGEE
d h d h d h d h d h d h Jan 7 21 May 24 5 Oct 6 20 Jan 19 18 Jun 6 6 Oct 22 18 Feb 2 5 Jun 21 13 Nov 4 1 Feb 16 15 Jul 3 18 Nov 19 5 28 10 Jul 19 13 Dec 2 13 Mar 16 10 31 10 Dec 16 6 Mar 28 10 Aug 15 12 31 2 Apr 12 22 Aug 28 5 Apr 25 19 Sep 9 13 May 10 2 Sep 25 0 10
LIBRATION Maxinun Minima Maxima Minimus Date Size P.A. Date Size P.A. Date Size P.A. Date Size P.A. d * d ' d d Jan 6.32 6.8 151 Jan 12.26 5.5 267 Jul 15.15 7.9 122 Jul 21.24 4.1 236 21.73 6.9 31 28.49 4.7 89 27.70 8.0 344 Aug 4.80 4.4 55 Feb 3.36 6.8 171 Feb 9.52 4.8 285 Aug 11.79 7.3 134 18.04 3.8 250 19.04 7.1 39 25.83 5.2 103 24.51 7.6 349 31.62 4.7 51 Mar 3.43 7.1 192 Mar 9.66 5.0 303 Sep 7.94 6.9 138 Sep 14.46 4.4 260 21.21 7.3 58 27.01 6.2 126 20.91 7.4 351 27.14 4.8 43 Apr 1.04 7.3 219 Apr 7.07 5.9 322 Oct 3.57 7.3 113 Oct 10.76 5.5 245 20.79 7.9 85 26.19 6.5 169 17.72 7.6 346 24.24 4.5 41 May 1.12 7.4 271 May 12.88 6.0 41 30.76 8.5 104 MOV 5.68 5.4 212 19.73 8.4 99 25.52 5.9 2 0 2 Roy 13.03 8.4 335 20.77 3.9 41 31.94 7.8 322 Jun 10.21 5.2 46 27.72 9.5 105 Dec 3.65 4.3 216 Jun 17.12 8.4 110 23.08 5.0 222 Dec 10.29 9.3 332 18.45 3.2 42 29.57 8.1 336 Jul 8.21 4.5 52 25.74 9.7 109 31.87 2.9 226
NOTE: Size of libration is given as an angle measured at the centre of the Moon Position Angle (P.A.) is measured through East on the face of the Moon from the North point of the disk. 11 1990 TIKES Of HOOK RISE AND SET CAPE TORN for PORT ELIZABETH subtract 28 MINUTES JANUARY FEBRUARY MARCH APRIL KAY JUNE Rise Set Rise Set Rise Set Rise set Rise set Rise Set h n h d t B b a h e b e b n h g h 9 h ■ h a h a 1 09 46 22 55 12 03 22 59 11 02 21 38 13 25 23 08 13 40 13 37 01 12 2 10 51 23 23 13 13 23 38 12 14 22 21 14 18 14 13 00 18 14 03 02 09 3 11 56 23 52 14 24 13 25 23 12 15 03 00 15 14 42 01 21 14 29 03 06 4 13 02 15 33 00 23 14 32 15 39 01 21 15 09 02 20 14 57 04 02 5 14 11 00 23 16 38 01 16 15 31 00 11 16 11 02 25 15 34 03 18 15 29 05 00
6 15 22 00 58 17 35 02 17 16 21 01 15 16 39 03 26 15 59 04 15 16 04 05 57 n 16 34 01 39 18 23 03 24 17 02 02 21 17 05 04 26 16 26 05 11 16 46 06 55 8 17 45 02 28 19 03 04 32 17 38 03 28 17 30 05 23 16 55 06 08 17 33 07 50 9 18 49 03 26 19 37 05 39 18 08 04 32 17 55 06 20 17 28 07 06 18 27 08 42 10 19 44 04 31 20 07 06 43 18 35 05 33 18 23 07 17 18 05 08 04 19 24 09 29 11 20 30 05 41 20 33 07 45 19 01 06 33 18 53 08 14 18 48 09 01 20 25 10 11 12 21 07 06 50 20 59 08 44 19 26 07 30 19 26 09 12 19 37 09 55 21 26 10 47 13 21 39 07 57 21 24 09 42 19 52 08 28 20 05 10 10 20 31 10 46 22 28 11 20 14 22 07 09 00 21 51 10 39 20 20 09 25 20 50 11 07 21 30 11 31 23 30 11 49 15 22 33 10 00 22 19 11 36 20 51 10 23 21 41 12 00 22 31 12 11 12 18 16 22 58 10 58 22 52 12 34 21 27 U 21 22 37 12 49 23 33 12 46 00 32 12 48 17 23 23 11 54 23 30 13 32 22 08 12 19 23 37 13 33 13 18 01 37 13 16 18 23 50 12 51 14 30 22 55 13 15 14 12 00 35 13 47 02 44 13 50 19 13 45 00 13 15 26 23 49 14 08 00 40 14 47 01 39 14 16 03 55 14 29 20 00 20 14 46 01 04 16 18 14 56 01 44 15 19 02 44 14 46 05 09 15 16
21 00 55 15 45 02 02 17 04 00 48 15 39 02 49 15 49 03 52 15 19 06 23 16 13 22 01 35 16 43 03 04 17 46 01 51 16 17 03 55 16 19 05 03 15 56 07 33 17 19 23 02 23 17 37 04 10 18 22 02 56 16 51 05 04 16 51 06 18 16 39 08 34 18 30 24 03 17 18 28 05 17 IS 55 04 02 17 22 06 15 17 26 07 35 17 32 09 25 19 42 25 04 18 19 12 06 25 19 26 05 10 17 53 07 30 18 06 08 48 18 34 10 07 20 52 26 05 23 19 51 07 32 19 56 06 19 18 24 08 47 18 54 09 54 19 43 10 41 21 58 27 06 29 20 26 08 41 20 27 07 29 18 57 10 02 19 51 10 50 20 54 11 11 23 00 28 07 36 20 57 09 51 21 00 08 42 19 33 11 11 20 55 11 35 22 04 11 39 29 08 42 21 26 09 57 20 16 12 10 22 03 12 12 23 10 12 05 00 00 30 09 45 21 55 11 11 21 06 12 59 23 12 12 44 12 31 00 57 31 10 55 22 26 12 22 22 04 13 11 00 12 JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set h e h a h n h b h n h b h d b ■ h a b d b B h B 1 12 59 01 55 13 22 03 35 14 54 04 42 15 46 04 22 17 51 04 20 19 06 04 10 2 13 29 02 52 14 12 04 30 15 57 05 20 16 50 04 52 19 05 04 55 20 18 05 04 3 14 03 03 50 15 07 05 21 17 00 05 54 17 57 05 22 20 20 05 37 21 23 06 08 4 14 43 04 43 16 06 06 06 18 05 06 25 19 05 05 52 21 34 06 27 22 18 07 19 5 15 28 05 44 17 08 06 47 19 09 06 54 20 16 06 26 22 42 07 25 23 04 08 33 6 16 20 06 37 18 12 07 23 20 16 07 24 21 30 07 03 23 40 08 31 23 41 09 44 7 17 17 07 26 19 15 07 55 21 24 07 55 22 43 07 47 09 41 10 52 8 18 17 08 10 20 18 08 25 22 34 08 28 23 52 08 39 00 28 10 51 OO 13 11 56 9 19 19 08 48 21 22 08 53 23 45 09 07 09 39 01 09 11 59 00 42 12 56 10 20 22 09 22 22 27 09 22 09 52 00 54 10 44 01 42 13 03 01 09 13 55 11 21 24 09 53 23 34 09 53 00 55 10 45 01 47 11 53 02 12 14 04 01 37 14 53 12 22 26 10 22 10 27 02 01 11 45 02 31 13 00 02 40 15 03 02 05 15 51 13 23 29 10 50 00 44 11 07 02 59 12 51 03 08 14 06 03 06 16 01 02 36 16 49 14 11 19 01 54 11 54 03 49 14 '30 03 40 15 08 03 34 16 59 03 10 17 47 15 00 34 11 50 03 03 12 49 04 31 15 08 04 09 16 09 04 02 17 57 03 49 18 43 16 01 42 12 26 04 08 13 52 05 07 16 13 04 36 17 08 04 34 18 55 04 33 19 36 17 02 53 13 08 05 04 15 01 05 38 17 16 05 03 18 07 05 10 19 53 05 22 20 24 18 04 05 13 59 05 52 16 11 06 06 18 17 05 31 19 05 05 50 20 48 06 16 21 08 19 05 15 14 59 06 33 17 20 06 33 19 17 06 00 20 04 06 36 21 40 07 14 21 46 20 06 18 16 07 07 07 18 26 07 01 20 16 06 33 21 03 07 27 22 27 08 12 22 20 21 07 13 17 19 07 37 19 30 07 29 21 16 07 10 22 00 08 22 23 08 09 11 22 50 22 07 59 18 30 08 05 20 31 07 59 22 14 07 52 22 55 09 19 23 45 10 10 23 19 23 08 37 19 39 08 32 21 30 08 34 23 13 08 40 23 45 10 18 11 09 23 46 24 09 09 20 44 09 00 22 29 09 12 09 32 11 17 00 18 12 09 25 09 38 21 46 09 28 23 28 09 56 OO 09 10 29 00 30 12 17 00 48 13 12 00 14 26 10 05 22 45 10 00 10 46 01 03 11 27 01 11 13 18 01 16 14 17 00 44 27 10 32 23 44 10 36 00 26 11 4i 01 52 12 27 01 46 14 21 01 45 15 26 01 18 23 10 59 11 17 01 24 12 39 02 36 13 29 02 19 15 27 02 14 16 38 01 58 29 11 29 00 42 12 03 02 20 13 40 03 15 14 31 02 49 16 37 02 47 17 51 02 46 30 12 02 01 40 12 55 03 12 14 43 03 50 15 34 03 18 17 50 03 25 19 00 03 44 31 12 39 02 38 13 53 04 00 16 41 03 48 20 01 04 51 12
1990 TIKES OF HOOK RISE AND SET JOBAHNESBOEG JAH0AEÏ FEBEOAE? HAKCH APEIL HAÏ JUKE Else Set Else Set Eise Set Eise Set Eise Set Eise Set h n h a h a h a h a h c h a b a b a b a h a h a 1 09 14 22 11 11 12 22 33 10 08 21 14 12 22 22 51 12 45 23 52 12 59 00 34 2 10 14 22 44 12 17 23 16 11 16 22 02 13 18 23 55 13 23 13 28 01 27 3 11 14 23 18 13 24 12 24 22 55 14 05 13 57 OO 50 13 59 02 19 4 12 15 23 54 14 31 00 04 13 29 23 55 14 46 00 58 14 27 01 46 14 31 03 12 5 13 19 15 35 01 00 14 28 15 22 01 58 14 57 02 39 15 06 04 06 6 14 25 00 33 16 33 02 01 15 21 00 57 15 54 02 55 15 26 03 32 15 45 05 00 7 15 34 01 18 17 24 03 05 16 06 02 01 16 24 03 50 15 57 04 24 16 28 05 55 8 16 42 02 10 18 09 04 10 16 46 03 03 16 54 04 43 16 30 05 17 17 17 06 49 9 17 46 03 09 18 47 05 13 17 20 04 03 17 23 05 36 17 06 06 11 18 09 07 41 10 18 43 04 14 19 21 06 13 17 52 05 00 17 55 06 28 17 46 07 05 19 05 08 29 11 19 32 05 21 19 52 07 10 18 22 05 55 18 28 07 22 18 31 08 00 20 02 09 13 12 20 15 06 27 20 22 08 05 18 52 06 49 19 06 08 16 19 20 08 53 21 00 09 53 13 20 51 07 29 20 51 08 58 19 22 07 42 19 47 09 11 20 14 09 44 21 58 10 30 14 21 23 08 28 21 22 09 51 19 54 08 35 20 33 10 05 21 10 10 31 22 55 11 04 15 21 54 09 23 21 55 10 44 20 29 09 29 21 24 10 58 22 07 11 14 23 53 11 37 16 22 23 10 17 22 31 11 38 21 07 10 24 22 19 11 48 23 05 11 53 12 10 17 22 52 11 09 23 11 12 33 21 50 11 19 23 17 12 34 12 29 00 53 12 45 18 23 23 12 01 23 57 13 29 22 39 12 13 13 16 00 04 13 03 01 55 13 23 19 23 57 12 55 14 23 23 32 13 06 00 16 13 55 01 02 13 37 03 01 14 06 20 13 49 00 48 15 16 13 55 01 15 14 31 02 03 14 11 04 11 14 57 21 00 35 14 45 01 44 16 04 00 29 14 41 02 16 15 06 03 06 14 49 05 22 15 56 22 01 18 15 40 02 44 16 49 01 29 15 22 03 17 15 41 04 12 15 30 06 31 17 01 23 02 07 16 35 03 46 17 30 02 30 16 01 04 20 16 18 05 22 16 18 07 33 18 11 24 03 01 17 26 04 49 18 08 03 32 16 37 05 27 16 58 06 35 17 14 08 27 19 19 25 04 00 18 14 05 51 18 43 04 34 17 13 06 36 17 43 07 46 18 17 09 13 20 25 26 05 01 18 57 06 54 19 18 05 38 17 49 07 48 18 35 08 52 19 25 09 52 21 26 27 06 03 19 36 07 57 19 54 06 43 18 27 09 00 19 34 09 50 20 33 10 27 22 24 28 07 05 20 12 09 02 20 32 07 51 19 08 10 08 20 38 10 39 21 39 10 59 23 19 29 08 06 20 46 09 00 19 55 11 09 21 44 11 20 22 41 11 29 30 09 07 21 20 10 11 20 48 12 01 22 49 11 56 23 39 11 59 00 13 31 10 09 21 55 11 19 21 48 12 29 JOLT AUGCST SEPTEHBEK OCTOBEE HOVEHBEE DECENBEE Else Set Else Set Eise Set Eise Set Eise Set Else Set h n 1) a h a h a h a h a b a b a h a b a h a b a 1 12 31 01 06 13 05 02 34 14 32 03 44 15 14 03 34 17 02 03 48 18 06 03 49 2 13 05 01 59 13 55 03 28 15 31 04 25 16 13 04 09 18 10 04 28 19 17 04 46 3 13 43 02 53 14 49 04 19 16 30 05 03 17 15 04 43 19 21 05 14 20 22 05 51 4 14 25 03 48 15 46 05 07 17 30 05 39 18 18 05 18 20 33 06 07 21 20 07 00 5 15 11 04 43 16 45 05 50 18 30 06 13 19 24 05 56 21 40 07 08 22 09 08 10 6 16 03 05 36 17 44 06 30 19 31 06 47 20 33 06 39 22 40 08 13 22 51 09 18 7 16 59 06 26 18 43 07 06 20 34 07 23 21 43 07 27 23 32 09 21 23 28 10 21 8 17 56 07 11 19 42 07 41 21 40 08 01 22 50 08 21 10 28 11 20 9 18 54 07 53 20 41 08 14 22 47 08 44 23 53 09 22 00 16 11 31 00 01 12 17 10 19 53 08 31 21 41 08 47 23 54 09 32 10 26 00 54 12 31 00 33 13 12 11 20 50 09 06 22 43 09 23 10 27 00 48 11 32 01 28 13 27 01 04 14 05 12 21 48 09 39 23 48 10 01 00 59 11 28 01 35 12 36 02 00 14 22 01 36 14 59 13 22 46 10 12 10 45 01 58 12 33 02 16 13 37 02 31 15 16 02 11 15 54 14 23 47 10 45 00 55 11 35 02 51 13 38 02 53 14 35 03 02 16 10 02 48 16 48 15 11 21 02 01 12 32 03 36 14 42 03 26 15 31 03 35 17 04 03 29 17 43 16 00 50 12 01 03 05 13 35 04 16 15 43 03 57 16 26 04 10 17 59 04 15 18 35 17 01 56 12 48 04 04 14 41 04 52 16 42 04 28 17 21 04 49 18 54 05 05 19 24 18 03 04 13 41 04 55 15 48 05 25 17 38 05 00 18 15 05 31 19 47 05 58 20 09 19 04 12 14 42 05 39 16 53 05 56 18 34 05 34 19 10 06 18 20 39 06 53 20 50 20 05 16 15 49 06 18 17 54 06 28 19 29 06 10 20 05 07 09 21 27 07 48 21 28 21 06 14 16 58 06 53 18 53 07 00 20 24 06 50 21 00 08 03 22 11 08 43 22 02 22 07 03 18 05 07 26 19 49 07 35 21 19 07 34 21 53 08 57 22 51 09 38 22 35 23 07 46 19 09 07 57 20 45 03 12 22 14 08 23 22 44 09 53 23 27 10 33 23 06 24 08 23 20 10 08 29 21 39 08 53 23 08 09 14 23 31 10 48 11 29 23 39 25 08 56 21 07 09 01 22 34 09 39 10 09 11 44 00 01 12 26 26 09 28 22 02 09 37 23 29 10 29 00 01 11 05 00 14 12 40 00 34 13 27 00 13 27 09 59 22 56 10 16 11 23 00 51 12 01 00 53 13 39 01 06 14 32 00 51 28 10 30 23 50 10 59 00 24 12 19 01 37 12 58 01 29 14 40 01 41 15 40 01 35 29 11 03 11 46 01 18 13 16 02 19 13 56 02 03 15 45 02 18 16 50 02 26 30 11 40 00 45 12 38 02 10 14 15 02 58 14 55 02 37 16 54 03 00 17 58 03 26 31 12 20 01 39 13 34 02 59 15 57 03 11 19 01 04 33 13 1990 TIKES OF KOOK RISE HID SET FOR DORBA* For BLOEMFONTEIN add 19 MINUTES .JANUARY .FEBRUARY . MARCH . APRIL . MAY . JUNE Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set h ■ b 1 h b h Ei b ■ h d h a b i h n h ■ b h b l 1 08 58 22 01 11 04 22 15 10 02 20 54 12 20 22 28 12 40 23 33 12 46 00 20 2 10 00 22 32 12 11 22 55 11 11 21 40 13 15 23 33 13 16 13 14 01 15 3 11 02 23 03 13 20 23 42 12 21 22 32 14 01 13 47 00 33 13 42 02 09 4 12 05 23 37 14 28 13 26 23 31 14 40 00 37 14 16 01 31 14 13 03 04 5 13 11 15 33 00 36 14 26 15 14 01 39 14 44 02 26 14 46 03 59 6 14 20 00 14 16 31 01 37 15 18 00 34 15 45 02 38 15 11 03 20 15 23 04 55 7 15 30 00 57 17 21 02 43 16 02 01 39 16 13 03 35 15 40 04 14 16 06 05 51 8 16 39 01 47 18 03 03 49 16 39 02 43 16 40 04 30 16 11 05 09 16 54 06 46 9 17 44 02 46 18 40 04 54 17 12 03 45 17 08 05 25 16 45 06 05 17 47 07 38 10 18 40 03 51 19 12 05 56 17 42 04 44 17 37 06 19 17 24 07 01 18 43 08 26 11 19 28 04 59 19 41 06 55 18 10 05 41 18 09 07 15 18 08 07 57 19 42 09 09 12 20 08 06 06 20 09 07 52 18 37 06 37 18 45 08 11 18 57 08 51 20 41 09 47 13 20 43 07 11 20 36 08 47 19 06 07 32 19 25 09 07 19 51 09 41 21 41 10 22 14 21 13 08 11 21 05 09 42 19 36 08 27 20 11 10 02 20 48 10 28 22 40 10 54 15 21 42 09 09 21 36 10 37 20 09 09 22 21 01 10 56 21 47 11 09 23 40 11 25 16 22 09 10 04 22 10 11 33 20 46 10 19 21 57 11 45 22 47 11 47 11 58 17 22 36 10 59 22 49 12 29 21 28 11 15 22 55 12 31 23 47 12 21 00 42 12 29 18 23 06 11 53 23 34 13 26 22 16 12 10 23 56 13 11 12 53 01 47 13 05 19 23 38 12 48 14 21 23 09 13 03 13 48 00 48 13 24 02 55 13 46 20 13 44 OO 25 15 13 13 52 00 57 14 23 01 50 13 57 04 06 14 35 21 00 14 14 41 01 21 16 01 00 07 14 36 02 00 14 55 02 55 14 32 05 19 15 33 22 OO 55 15 38 02 22 16 44 01 08 15 17 03 03 15 28 04 04 15 11 06 28 16 38 23 01 43 16 32 03 26 17 23 02 11 15 53 04 09 16 02 05 16 15 57 07 30 17 48 24 02 38 17 24 04 31 17 59 03 15 16 27 05 18 16 40 06 30 16 51 08 23 18 59 25 03 37 18 10 05 36 18 32 04 19 17 01 06 30 17 23 07 43 17 54 09 07 20 06 26 04 40 18 51 06 41 19 05 05 25 17 34 07 44 18 13 08 49 19 02 09 45 21 10 27 05 44 19 28 07 46 19 39 06 33 18 10 08 57 19 10 09 46 20 12 10 17 22 10 28 06 48 20 02 08 53 20 14 07 43 18 49 10 06 20 14 10 34 21 19 10 47 23 07 29 07 52 20 34 08 55 19 34 11 06 21 22 11 14 22 23 11 15 30 08 55 21 06 10 07 20 26 11 57 22 29 11 48 23 23 11 44 00 02 31 09 59 21 39 11 17 21 24 12 18 JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set h b h b h B b B b n b 1 h i b b b b b d h d b i 1 12 14 00 57 12 42 02 31 14 11 03 40 14 57 03 25 16 53 03 32 18 02 03 28 2 12 46 01 52 13 32 03 25 15 12 04 20 15 59 03 58 18 04 04 10 19 13 04 24 3 13 22 02 48 14 26 04 16 16 13 04 56 17 03 04 30 19 17 04 54 20 19 05 28 4 14 03 03 44 15 25 05 03 17 15 05 29 18 08 05 03 20 29 05 45 21 16 06 38 5 14 49 04 40 16 25 05 45 18 17 06 01 19 17 05 39 21 37 06 45 22 04 07 50 6 15 40 05 33 17 26 06 24 19 20 06 34 20 28 06 19 22 37 07 51 22 44 08 59 7 16 36 06 22 18 27 06 58 20 26 07 07 21 39 07 05 23 27 08 59 23 19 10 04 8 17 35 07 08 19 27 07 30 21 33 07 43 22 47 07 58 10 07 23 50 11 06 9 18 35 07 48 20 29 08 01 22 42 08 24 23 50 08 58 00 10 11 13 12 04 10 19 35 08 24 21 31 08 33 23 51 09 11 10 03 00 46 12 14 00 19 13 00 11 20 35 08 57 22 35 09 06 10 04 00 44 11 10 01 18 13 13 00 49 13 56 12 21 34 09 28 23 42 09 43 00 56 11 05 01 30 12 16 01 48 14 10 01 19 14 52 13 22 35 09 59 10 24 01 55 12 10 02 10 13 19 02 17 15 05 01 52 15 48 14 23 37 10 30 00 51 11 13 02 47 13 17 02 44 14 19 02 46 16 01 02 28 16 44 15 11 04 01 58 12 09 03 31 14 22 03 16 15 18 03 17 16 57 03 08 17 39 16 00 43 11 42 03 03 13 12 04 09 15 26 03 45 16 14 03 51 17 53 03 53 18 32 17 01 51 12 26 04 01 14 19 04 43 16 26 04 14 17 11 04 28 IS 50 04 42 19 21 18 03 01 13 19 04 51 15 28 05 14 17 25 04 44 18 07 05 10 19 44 05 36 20 05 19 04 10 14 19 05 33 16 34 05 43 18 23 05 16 19 04 05 56 20 36 06 32 20 45 20 05 14 15 26 06 10 17 38 06 13 19 19 05 50 20 00 06 47 21 23 07 28 21 21 21 06 10 16 36 06 43 18 39 06 43 20 16 06 29 20 56 07 41 22 06 08 25 21 54 22 06 58 17 46 07 14 19 37 07 16 21 13 07 12 21 50 08 37 22 45 09 22 22 24 23 07 39 18 52 07 43 20 34 07 52 22 10 08 00 22 41 09 34 23 20 10 19 22 54 24 08 14 19 54 08 13 21 31 08 32 23 05 08 52 23 27 10 31 23 52 11 16 23 24 25 08 45 20 53 08 44 22 28 09 17 23 58 09 47 11 28 12 16 23 57 26 09 15 21 51 09 17 23 24 10 06 10 44 00 09 12 27 00 23 13 19 27 09 44 22 47 09 54 11 00 00 48 11 42 00 47 13 27 00 53 14 25 00 33 28 10 13 23 43 10 36 OO 20 11 57 01 33 12 41 01 21 14 30 01 26 15 35 01 15 29 10 45 11 23 01 15 12 56 0? 14 13 41 01 54 15 37 02 01 16 47 02 04 30 11 19 00 39 12 16 02 07 13 57 02 51 14 41 02 25 16 48 02 41 17 55 03 03 31 11 58 01 35 13 12 02 56 15 46 02 58 18 57 04 10 14
COM PUT X NO AIMO SOLAR SECTIONS
COMPUTING SECTION This newly formed section invites all those interested in Astronomical Computing in any form to share their expertise and any Software they may have with other members in the Society. The objectives of The Computing Section were outlined in M.N.A.S.S.A. Vol 46 Nos. 5 & 6 June 1987 page 66. Please refer to this write up for detailed information. Persons interested in the activities of the Computing Section are urged to contact the Director of the Society's Computing Section: Mr Tony Hilton, P 0 Box 68846, Bryanston, 2021. Phone (w) 011-4032422. Mr Hilton is in the process of compiling a comprehensive DATA BASE of all interested person's, equipment, available software etc. This report will be available to all interested persons in the first quarter of 1988. If you wish to become a subscriber to this DATA BASE list please contact Mr Hilton for the relevant questionnaire. Furthermore, if you are embarking on any Computer Projects, Mr Hilton would like to hear from you, and would make himself or any other competent individuals available to supply expert advice or additional information where necessary.
SOLAR SECTION The work undertaken by this section covers a broad range of techniques to observe activity on the sun's disk. Members of the section note their observations on appropriate forms, which are then forwarded to various organisations in the United States of America, the United Kingdom, the Federal Republic of Germany and South Africa. The results we provide are further reduced by these organisations and incorporated with the information provided by other world-wide groups of Solar Observers, such as ours. The data produced is then fed to over 450 scientific institutions all over the world, where it is used by a very wide range of scientific disciplines. Observational techniques employed include the visual observation of the sun's disk (using suitable filters or by projecting the image onto an appropriate screen) to determine sun spots and active areas, the monitoring of solar flares by very low frequency radio waves and monitoring changes in the earth's magnetic field caused by solar activity. Other activities such as photographing and the drawing of visible solar features are also undertaken. A weekly update of solar activity is broadcast country wide on Sunday mornings at lOhOO and again on Monday evenings at 20h30 by the Amateur Radio League, enabling amateur astronomers and amateur radio enthusiasts alike to keep abreast of the latest developments as well as with all other interesting solar information. Short lectures are also given at this time. Towards the end of 1986, the Sun entered the new 11 year Solar cycle and this cycle is characterised by a steady climb over approximately 4h years, followed by a slower decline to minimum lasting approximately 6H years. 1990, will therefore experience a marked increase in Solar activity and provide the observer with much to look at. A word of caution - NEVER observe the sun directly without adequate filtration as permanent eye damage can occur,and do not use the screw-in filters provided with some commercial telescopes, as they are inclined to shatter! Large instruments are not a prerequisite! Any telescope from 50ram, reflector or refractor can be used and provides an ideal opportunity for owners of small instruments to contribute immediately to Science. If one has no filter, then the only safe method is to project the image on to a white card. Image quality will be enhanced if the card is kept in the shade, or enclosed in a screen. Details of suitable filters are best sought from experienced solar observers or from the Director of the Solar Section. Persons interested in observing the sun,or requiring information are invited to contact The Director of the Solar Section: Jim Knight, at Mars Street, Atlasville, Boksburg, 1459 or at 011-9731380. THE PLANETS
BASIC DATA Dist iron Period of Equatorial Rotation Inclination No. of Sun Revolution Mass Dianeter Period of Equator knovn 106 hi years (Earth = 1) 10 hi to orbit satellites Mercury 5« 0,24 0,055 4,98 58.65d o' 0 Venus 108 0,62 0,815 12,10 243d S 178' 0 Earth 150 1,00 1,000 12,76 23h56« 23*27' 1 Mars 22« 1,88 0,107 6,79 241)37» 23*59' 2 Jupiter 778 11,9 318,867 142,80 09h51n 03*04' 16 Saturn 1 426 29,5 95,142 120,00 101)14» 26*44' 17 Uranus 2 868 84,0 14,559 52,00 101)49» R 77*53' 15 Meptune 4 494 164,8 17,207 48,40 161)031 28*48' 8 Pluto 5 896 247,6 0,002 3,00 6.39d 118*? 1
GENERAL Apart from Uranus, Neptune and Pluto, the planets of our solar system are amongst the brightest objects in the night sky. Unlike the distant stars, their relative positions do not remain fixed,but continually change as, like the Earth, they orbit around the Sun. Their apparent movements against the starry background are complicated as they result from a combination of their own motion and the Earth's motion. Their brightnesses also vary considerably, as both their distances from the Earth and the visible portions of their sunlit hemispheres change. Since the period of a planet increases with increasing distance from the Sun, so we find that the inner planets - Mercury and Venus - appear to "overtake" the Earth in their orbits, while the Earth in turn "overtakes” the outer planets - Mars, Jupiter and Saturn. The terms given in astronony to the various Sun-Earth-Planet configurations are illustrated in the accompanying diagram. Dates of such configurations occuring in 1990 are listed chronologically in the Diary (pages 4 and 5) and are also mentioned in the text below.
OBSERVING THE PLANETS To the naked eye, planets appear as virtually point sources of light. However, their disks can be readily resolved with the aid of a small telescope. Even so, their angular diameters are of the order of 10 seconds of arc - roughly 1/200 of the Moon's angular diameter - so it is not always possible to distinguish details on their disks. The disks of Mercury and Venus are only seen fully illuminated when they are furthest from us - as they draw closer, their disks grow larger but the phase changes to a crescent as we see more of their dark hemispheres. In contrast, the disks of the outer planets are always seen fully or near fully illuminated. 16
TIMES OF RISING AND SETTING
The times of rising and setting given by the diagram are accurate for position 30° East, 30° South and approximately correct for other places in Southern Africa. Strictly speaking, corrections for latitude and longitude should be applied, but the latitude correction is in general sufficiently small to be ignored and in no case will exceed 15 minutes.
JAN FEB MAR APR MAY JUN 17
CORRECTION FOR PLACES NOT ON THE 30° E MERIDIAN
Approximate longitude corrections from the 30° East meridian are:
Bloemfontein +15® East London +8 Port Elizabeth +18“ Bulawayo +6® Grahamstown +14“ Pretoria +7“ Cape Town +46® Johannesburg +8“ Harare -4“ Durban -4“ Kimberley +21® Windhoek +52“
JUL AUG SEP OCT NOV DEC 5 p.m .
6 p.m .
7 p .m -
8 p.m.
9 p .m .
10 p.m ,
I 1 p.m .
A id n igh t
1 o.m.
2 o. m.
3 q. m.
A a. m.
5 o. m.
6 o.m .
7 o .m . 18
MERCURY The planet may be seen low in the east before sunrise between the following approximate dates: January 15 (at. mag.+1.8) to March 9 (at mag.-0.9), May 13 (at mag.+3.0) to June 25 (at mag.-1.4), September 16 (at mag.+1.7) to October 10 (at mag.-1.2) and December 30 to 31 (at mag.+1.4). The best conditions for viewing will occur from the last week in January when Mercury is in Sagitarius to the end of February when it is in Capricornus.
Mercury may also be seen low in the west after sunset between the following approximate dates: January 1 (at mag.+0.7) to January 3 (at mag.+1.5), March 28 (at mag.-1.5) to April 25 (at mag.+2.6), July 11 (at mag.-1.2) to September 1 (at mag.+2.5), and November 7 (at mag.-0.6) to December 18 (at mag.+1.4) The best conditions for viowing will be from the last: week in July until late August when Mercury is in Leo.
d h d h d b d h Superior Conjunction Jul 2 19 Oct 22 6 Greatest Elongation East Apr 13 1? (20°) Aug 11 22 (27°) Dec 6 9 (21°) Stationary Apr 23 17 Aug 25 2 Dec 14 20 Inferior Conjunction Jan 9 4 May 4 2 Sep 8 6 Dec 24 10 Stationary Jan 20 5 May 16 9 Sep 16 18 Greatest Elongation West Feb 1 3 (25°) May 31 5 (25°) Sep 24 6 (18°)
VENUS Venus will first be in the evening sky in the first week of January (at mag. 1.5) and again from mid to end December (at mag.-3.8). It will be in the morning sky from the end of January (at mag.-4.3) untill after mid September (at mag.-3.8).
MARS Mars begins the year in the constellation of Ophiuchus in the morning sky (at mag. +1.5) and will rise earlier each day becoming an all night object by the end of November (at mag.+2.0). It will move to Sagitarius (February), Capricornus (March, April), Aquarius, Pices (May), enter Cetus, return to Pices (June, July) before moving to Aries (August) and Taurus (September to December).
Jupiter begins the year in Gemini (at ma g . -2.7) where it is visible for most of the night. It will be too close to the Sun to be seen by late June. Jupiter re-appears in the morning sky in late July (at mag.-1.8) and in early August passes into Cancer where it will remain for the rest of the year. It will be at magnitude -2.5 at the end of the year. 19 SATURN Saturn will return to the morning sky a few days after mid January in Sagitarius where it will remain for the year. It will be visible all night by mid July and by mid October be seen only in the evening sky. Its magnitude will increase from +5.6 at the beginning of February to +0.1 in July and decrease to +0.5 by mid Octo b e r . South
APPARENT PLACES: Mercury Venus Mars Jupi.ter RA DEC RA DEC RA DF.C RA DEC * h m ■ h m • • h m ' h in * Jan i 19 49. 6 -20 19 20 32. 2 -16 49 16 34..4 -22 1 6 22..2 23 14 Jan u 19 3. 4 -19 20 20 1 >. 8 -L5 8 17 4. 7 -22 59 6 16. 6 23 18 Jan 21 18 42.,1 -20 23 19 3U. 2 -14 19 17 35..7 -23 36 6 11. 6 23 21 Jan 31 19 1 1 .4 -21 7 9 19 30. 6 -14 19 18 7. 1 -23 49 6 7. 6 23 23 Feb 10 20 2 ..5 -21 3 19 76..5 -14 50 18 38..7 -23 40 6 4..9 23 25 Feb 20 21 2. 1 -18 36 19 38. 3 -15 2? 19 10. 4 -23 7 6 3. 6 23 27
Mar 2 22 >.. 7 -14 0 20 2. 0 -15 .33 19 41 .9 -22 10 6 3..8 23 28 Mar 12 23 12 .2 - 7 13 20 3.3. 3 -15 7 20 13..2 -20 52 6 5. 4 23 29 Mar 22 0 22..3 1 24 21 9..8 -13 54 20 44 .0 -19 13 6 8..3 23 29 Apr 1 1 33. 3 10 40 21 49. 0 -11 55 21 14..3 -17 16 6 12. 4 23 29 Apr 11 2 30..8 1 7 32 22 29..5 -9 13 21 44..0 -15 2 6 17.,7 23 28 Apr 21 2 56. 4 19 46 23 10..8 -5 54 22 13.,1 -12 36 6 23. 9 23 26
May 1 2 47. 7 1 7 15 23 52..4 -2 9 22 41..6 -9 59 6 30,.9 23 23 May ! 1 2 28. 4 12 52 0 34. 4 1 53 23 9..6 -7 14 6 38. 6 23 17 May 21 2 30 .0 11 12 1 17..1 6 2 23 37..2 -4 25 6 46..9 23 9 May 31 2 57. 0 13 10 2 0..8 10 6 0 4,,4 -1 34 6 55. 6 22 60 Jun 10 3 46,.0 17 23 2 45..9 13 55 0 31..3 1 15 7 4. 7 22 47 Jun 20 4 57..2 21 59 3 32..7 17 15 0 57,.8 3 60 7 14..1 22 33 CM Jun 30 6 28..3 24 21 4 21 .4 19 57 1 24 .1 6 38 7 . 5 22 16
Jul 10 8 0. 6 22 25 5 11. 8 21 49 1 ‘>0. 0 9 7 7 33..1 21 5/ Jul 20 9 17 . L 17 20 6 .3..5 22 43 2 15 . 3 11 25 7 42 .6 21 35 Jul 30 10 16..2 11 2 6 55. 9 22 33 2 40..5 13 29 7 57..1 21 12 Aug 9 10 59 .9 4 55 7 48 .0 21 19 3 4 . 7 15 19 8 ! ,3 20 48 Aug 19 11 26..0 0 12 8 39 .2 19 3 3 27..8 16 5:, 8 10..3 20 22 Aug 29 11 26 .1 -1 10 9 28 .9 15 52 3 49 .4 18 13 8 19 .0 19 56
Sep 8 10 57.,9 2 50 10 17, 1 11 >7 4 9., 1 19 22 8 2/..7 19 29 Sep 18 10 44 . 3 7 32 11 4 .0 7 29 4 26 .7 20 16 8 34..8 19 3 Sep 28 11 21 .4 5 55 1 1 50. 1 2 39 4 39..8 20 59 8 41.,9 18 39 Oct 8 1 7 22 .8 -0 28 12 35 .8 -2 21 4 49 . 1 21 35 8 48 .2 18 16 Oct 18 13 26..2 -7 54 13 21. 9 -7 18 4 33. 1 22 4 8 53,. / 1 / 56 Oct 28 14 28 . 1 -14 39 14 9..0 -11 59 4 il .0 22 27 8 58 .2 17 39
Nov / 15 30 . 1 -20 8 14 57 .8 -16 12 4 42 .6 22 42 9 1..6 17 27 Nov 17 16 33 .7 -23 58 15 48 .5 -19 42 4 28 .9 22 46 9 3..9 17 19 Nov 7 1 17 35 .8 -25 46 16 41 .2 -22 19 4 12 .6 22 38 9 4..9 17 17 Dec 7 18 28 . 3 -73 17 17 35 .4 -23 49 3 57 .3 22 21 9 4 .6 17 21 Dec 1 / 18 40 .0 -77 57 18 30 ,4 -24 8 3 46 .0 22 4 9 3,.0 1/ 30 Dec 7/ ) 7 50 . 1 -20 29 19 25..1 -23 11 3 40,.3 21 56 9 0,,1 17 44 20
APPARENT PLACES: Saturn Uranus Neptune Pluto RA DEC RA DEC RA DEC RA DEC h m ’ h m ' h m ' h m ' Jan i 19 8.0 -22 14 18 25.3 -23 35 18 52.1 -22 3 15 15.7 -2 15 Jan n 19 13.1 -22 6 !S 27.9 -23 34 18 53.7 -22 1 15 16.7 -2 15 Jan 21 19 18.1 -21 57 18 30.4 -23 32 18 55.3 -21 59 15 17.5 -2 14 Jan 31 19 23.0 -21 49 1 8 32.8 -23 30 18 56.8 -21 57 15 18.1 -2 11 Feb 10 19 27.7 -21 40 18 35.0 -23 29 18 58.2 -21 55 15 18.5 -2 8 Feb 20 19 32.1 -21 31 18 36.9 -23 27 18 59.5 -21 53 15 18.6 -2 4
Mar 2 19 36.1 -21 22 18 38.6 -23 26 19 0.6 -21 51 15 18.6 -1 59 Mar 12 19 39.7 -21 15 18 39.9 -23 25 19 1.5 -21 50 15 18.3 -1 53 Mar 22 19 42.8 -21 8 18 40.9 -23 24 19 2.2 -21 49 15 17.8 -1 47 Apr 1 19 45.3 -21 2 18 41.6 -23 24 19 2.6 -21 48 15 17.2 -1 41 Apr 11 19 47.2 -20 58 L8 41.8 -23 24 19 2.9 -21 47 15 16.3 -1 35 Apr 21 19 48.5 -20 55 18 41.7 -23 24 19 2.9 -21 47 15 15.4 -1 30
May 1 19 49.0 -20 54 18 41.2 -23 25 19 2.6 -21 47 15 14.4 -1 25 May 11 19 48.9 -20 55 18 40.4 -23 26 19 2.2 -21 48 15 13.4 -1 21 May 21 19 48.1 -20 58 18 39.3 -23 27 19 1.5 -21 49 15 12.3 -1 18 May 31 19 46.7 -21 3 18 38.0 -23 29 19 0.7 -21 50 15 11.3 -1 16 Jun 10 19 44.7 -21 8 18 36.4 -23 30 18 59.7 -21 51 15 10.4 -1 15 Jun 20 19 42.2 -21 15 18 34.7 -23 32 18 58.6 -21 53 15 9.6 -1 16 Jun 30 19 39.4 -21 23 18 33.0 -23 33 18 57.5 -21 54 15 8.9 -1 17
Jul 10 19 36.3 -21 31 ! 8 31.2 -23 35 18 56.3 -21 56 15 8.4 -1 21 Jul 20 19 33.2 -21 39 18 29.5 -23 36 18 55.2 -21 58 15 8.1 -1 25 Jul 30 19 30.2 -21 46 18 28.0 -23 37 18 54.1 -21 59 15 8.0 -1 30 Aug 9 19 27.4 -21 53 18 26.7 -23 38 18 53.2 -22 1 15 8.1 -1 37 Aug 19 19 25.0 -21 59 18 25.7 -23 38 18 52.3 -22 2 15 8.4 -1 44 Aug 29 19 23.1 -22 4 18 24.9 -23 39 18 51.7 -22 3 15 8.9 -1 52
Sep 8 19 21.7 -22 7 18 24.5 -23 39 18 51.2 -22 4 15 9.6 -2 0 Sep 18 19 21.1 -22 9 18 24.5 -23 39 18 51.0 -22 5 15 10.5 -2 9 Sep 28 19 21.2 -22 10 18 24.8 -23 39 18 51.0 -22 5 15 11.6 -2 18 Oct 8 19 21.9 -22 9 18 25.5 -23 38 18 51.3 -22 5 15 12.8 -2 27 Oct 18 19 23.4 -22 7 18 26.6 -23 37 18 51.7 -22 5 15 14.1 -2 35 Oct 28 19 25.5 -22 4 18 28.0 -23 36 18 52.4 -22 4 15 15.6 -2 43
Nov 7 19 28.2 -21 59 18 29.7 -23 35 18 53.4 -22 4 15 17.0 -2 50 Nov 17 19 31.5 -21 52 18 31.7 -23 34 18 54.5 -22 3 15 18.5 -2 57 Nov 27 19 35.2 -21 45 18 33.9 -23 32 18 55.8 -22 1 15 20.0 -3 2 Dec 7 19 39.4 -21 36 18 36.3 -23 30 18 57.2 -21 59 15 21.5 -3 7 Dec 17 19 43.9 -21 25 18 38.8 -23 28 18 58.7 -21 57 15 22.8 -3 10 Dec 27 19 48.6 -21 14 18 41.4 -23 25 19 0.3 -21 55 15 24.1 -3 13
EVENTS OF INTEREST Morning sky: late Jan. to early Feb. Mercury (the brighter object) close to Saturn 4 Feb. Venus in conjunction with Mercury 7 Feb. Venus in conjunction with Saturn 14 Feb. Venus in conjunction with Saturn late Feb. to early Mar. Mars (the fainter reddish object) close to Saturn 28 Feb. Mars in conjunction with Saturn mid Aug. Venus close to Jupiter 12 Aug. Venus in conjunction with Jupiter mid Sep. Venus (the brighter object) close to Mercury 14 Sep. Venus in conjunction with Mercury Evening sky: second week of Oct. Venus (the brighter object) close to Mercury mid Dec. Venus (the brighter object) close to Mercury 18 Dec Venus in conjunction with Mercury end D e c . Venus (the brighter object) in the sky with Saturn URANUS Uranus remains in Sagitarius all year. Its magnitude at opposition on June 29 is +5.6. Path of Uranus
Magnitudes 6 • 7 •
NEPTUNE Neptune is also in Sagitarius all year. Its magnitude at opposition on July 5 is +7.9. Path of Neptune
------• 5 J S g r * T T S g r •
* m a y j u n O S g r ( JUL AUG APfi N*S€P
X C NOV ^ o c r * • V JS g r • • • • »v's r •
%______t
12 08 04 19h00m 56 52 48 18h44m
Magnitudes: 34) 4* 5 • 6 * 7 • 8 •
PLUTO Pluto at magnitude +14 in Serpens is an object for a large telescope. 22
THE MOONS of JUPITER
One of the most popular sights for an observer with a small telescope is Jupiter and its moons. Four of the sixteen - lo, Europa, Ganymede and Callisto - are generally clearly visible - they would just be visible to the naked eye were it not for the glare from the mother planet. As the diagram below indicates, the system is seen almost edge-on so the moons always lie close to a straight line extending from the planet's equator. South
Ganymede Jupiter
As they orbit, so they appear to oscillate from one side to the other, alternately passing in front and behind the planet. This motion is represented in the diagrams on page 24 which cover the period when Jupiter is clearly visible in the evening sky. When the moons pass in front and behind the planet, transits, occultations and eclipses occur. Details of such phenomena occurring between the end of astronomical twilight and just after midnight (and when the planet is above the horizon in Southern Africa) are given in the table below.
EXPLANATION OF THE TABLE. - Date and predicted times are given; these are for mid-phenomean and are not instantaneous. - The moon concerned are I - Io, II - Europa, III - Ganymede and IV - Callisto. - Phenomena - the abbreviations used are D - Disappearance; Ec - Eclipse ie.the satellite passes through the shadow of Jupiter; R - Reappearance; Oc - Occultation ie.the satellite is obscured by the disc of Jupiter; I - Ingress; Sh - Shadow Transit ie.the shadow of the satellite transits the d i s c ; E - Egress; Tr - Transit ie.the satellite crosses the disc of Jupit
d h 1 d h 1 d h s d h ■ Jan 01 21 26 II.Ec.R. Jan 13 03 22 III.Sh.E. Jan 25 00 20 II.Sh.E. Feb 07 19 41 I.Sh.E. 04 05 01 I.Oc.B. 03 51 I.Ec.R. 28 01 50 I.Tr.I. 08 00 59 II.Tr.I. 05 02 09 I.Tr.I. 22 19 I.Tr.I. 02 34 I.Sh.I. 09 23 44 II.EC.R. 02 22 I.Sh.I. 22 45 I.Sh.I. 23 08 I.OC.D. 10 00 05 IV.Tr.I. 04 23 I.Tr.E. 14 00 33 I.Tr.E. 29 02 10 I.Ec.R. 01 44 IV.Tr.E. 04 36 I.Sh.E. 00 59 I.Sh.E. 20 16 I.Tr.I. 19 25 III.Sh.E. 19 25 III.Tr.I. 19 37 I.Oc.D. 21 03 I.Sh.I. 12 23 52 I.Tr.I. 20 21 Ill.Sh.I. 22 20 I.Ec.R. 22 30 I.Tr.E. 13 00 53 I.Sh.I. 22 23 III.Tr.E. 15 19 27 I.Sh.E. 23 17 I.Sh.E. 02 05 I.Tr.E. 23 21 III.Sh.E. 23 00 II.Oc.D. 30 20 38 I.EC.R. 21 11 I.Oc.D. 23 27 I.Oc.D. 23 55 IV.Oc.D. 22 11 III.OC.R. 14 00 29 I.Ec.R. 06 01 56 I.Ec.B. 16 01 24 IV.0C.R. 22 26 III.EC.D. 19 22 I.Sh.I. 20 35 I.Tr.I. 02 37 II.Ec.R. 31 01 31 III.Ec.R. 20 33 I.Tr.E. 20 50 I.Sh.I. 17 20 38 U.Tr.E. 22 37 II.Tr.I. 21 36 I.Sh.E. 22 48 I.Tr.E. 21 43 II.Sb.E. Feb 01 00 16 Il.Sh.I. 16 21 29 II.Oc.D. 23 04 I.Sh.E. 20 02 02 III.Tr.I. 01 15 II.Tr.E. 17 20 20 Ill.Sh.I. 07 02 34 II.Tr.I. 02 56 I.Oc.D. 02 57 II.Sh.E. 23 25 III.Sh.E. 03 06 n.sh.I. 21 00 04 I.Tr.I. 22 18 IV.Ec.D. 18 19 14 II.Tr.E. 20 00 IV.Tr.E. 00 39 I.Sh.I. 02 00 35 IV.Bc.R. 21 28 II.Sh.E. 20 25 I.Ec.R. 02 17 I.Tr.E. 21 07 II.EC.R. 20 23 01 I.OC.D. 21 04 IV.Sh.I. 02 53 I.Sh.E. 05 00 56 I.OC.D. 21 20 09 I.Tr.I. 22 54 IV.Sh.E. 21 22 I.Oc.D. 22 04 I.Tr.I. 21 17 i.sh.i. 08 20 45 II.Oc.D. 22 00 15 I.Ec.R. 22 58 I.Sh.I. 22 23 I.Tr.E. 09 00 01 II.Ec.E. 20 44 I.Tr.E. 06 00 17 I.Tr.E. 23 31 I.Sh.E. 12 03 53 I.Tr.I. 21 22 I.Sh.E. 01 12 I.Sh.E. 22 20 53 I.Ec.R. 04 16 I.Sh.I. 23 01 16 II.Oc.D. 19 23 I.Oc.D. 23 23 55 II.Oc.D. 22 42 III.Tr.I. 21 30 III.Ec.R. 22 34 I.EC.R. 24 19 38 III.Tr.I. 13 00 20 Ill.Sh.I. 24 20 17 II.Tr.I. 22 40 III.0C.D. 22 38 III.Tr.E. 01 11 I.Oc.D. 21 39 Il.Sh.I. 07 01 40 III.OC.R. 25 00 20 Ill.Sh.I. 01 40 III.Tr.E. 22 56 n.Tr.E. 02 26 III.Ec.D. 21 24 Il.Sh.I. d h « d h ■ d h d d h D Feb 25 21 42 Il.Tr.E. Apr 17 20 26 I.Sh.E. Oct 08 05 00 i.a .i. Hov 30 02 10 n .a .i. 26 00 05 II.Sh.E. 22 03 IV.Tr.I. 09 05 35 I.Oc.R. 04 30 II.Tr.I. 28 00 52 I.Oc.D. 19 18 29 III.Ec.D. 10 02 54 I.Tr.E. 05 03 n.a.E . 22 01 I.Tr.I. 21 44 III.Ec.R. 11 04 45 IV.Ec.D. Dec 01 02 30 IV.Oc.R. 23 12 i.sh.i. 21 20 49 II.Oc.D. 13 03 10 II.Ec.D. 04 18 I.Ec.D. Nar 01 00 14 I.Tr.E. 23 18 36 II.Tr.E. 15 02 38 II.Tr.E. 02 01 37 I.Sh.I. 19 20 I.Oc.D. 20 55 II.S.E. 16 02 59 III.OC.D. 02 15 II.OC.R. 22 48 I.Ec.R. 21 48 I.OC.D. 04 00 I.EC.D. 02 44 I.Tr.I. 02 19 55 I.Sh.E. 24 18 58 I.Tr.I. 17 02 34 I.Tr.I. 03 54 i.a.E. 03 23 24 III.Tr.I. 20 07 I.Sh.I. 03 38 I.Sh.E. 05 01 I.Tr.E. 04 21 33 Il.ïr.I. 21 12 I.Tr.E. 04 50 I.Tr.E. 03 02 13 I.OC.R. 05 00 00 Il.Sh.l. 25 19 41 I.EC.R. 20 02 40 IV.Tr.I. 23 28 I.Tr.E. 00 11 II.Tr.E. 26 19 48 IV.Ec.R. 22 02 25 II.Tr.I. 05 01 50 III.Ec.D. 06 20 53 II.Ec.R. 21 04 III.Oc.R. 02 46 II.a.E. 07 04 46 n .a .i. 22 44 IV.Oc.D. 30 18 38 II.Tr.I. 05 18 II.Tr.E. 08 23 37 III.Tr.E. 07 21 37 III.Ec.R. 20 47 Il.Sh.l. 23 02 02 III.Ec.D. 23 41 II.Ec.D. 23 53 I.Tr.I. 21 19 II.Tr.E. 24 03 15 i.a .i. 09 01 37 IV.Sh.E. 08 21 13 I.Oc.D. Hay 03 18 46 I.Sh.E. 04 29 I.Tr.I. 03 31 i.a .i. 09 19 36 I.a .i. 04 20 16 IV.Tr.E. 25 03 56 I.Oc.R. 04 33 I.Tr.I. 20 34 I.Ir.E. 07 19 38 III.Sh.E. 28 03 15 IV.Ec.R. 04 38 II.Oc.R. 21 50 I.Sh.E. 09 20 16 I.Oc.D. 29 02 30 n .a .i. 10 00 40 I.Ec.D. 10 19 12 I.Ec.R. 20 34 II.Ec.R. 05 03 II.Tr.I. 04 02 I.OC.R. 12 00 05 II.Tr.I. 10 18 26 I.Sh.I. 05 21 II.Sh.E. 23 00 I.Tr.I. 13 23 31 II.Ec.R. 19 42 I.Tr.E. 31 03 00 II.Oc.R. 23 03 II.Tr.E. 14 20 19 III.Oc.R. 20 42 I.Sh.E. 05 08 i.a .i. U 00 15 i.a.E. 22 28 III.Ec.D. 14 19 48 III.Tr.E. Hov 01 02 15 I.Ec.D. 01 16 I.Tr.E. 15 21 04 iv .a .i. 20 24 III.Sh.1. 02 01 53 i.a.E . 15 23 17 m .a.E . 23 06 I.Oc.D. 16 18 33 II.Oc.D. 03 08 I.Tr.E. 23 35 III.Tr.I. 23 52 IV.Sh.E. 17 19 28 I.Tr.I. 03 04 38 III.Tr.E. 16 02 14 II.EC.D. 16 20 15 I.Tr.I. 20 22 I.Sh.I. 05 05 06 Il.Sh.l. 03 10 III.Tr.E. 21 32 I.Sh.I. 18 19 54 I.EC.R. 06 01 38 IV.Tr.E. 17 02 34 I.Ec.D. 22 28 I.Tr.E. 25 18 46 I.Oc.D. 08 04 09 I.Ec.D. 04 44 IV.Ec.D. 23 46 I.Sh.E. 18 59 II.Tr.E. 09 01 30 i.a .i. 22 32 II.Tr.I. 17 21 08 I.Ec.R. 26 19 02 I.a.E. 02 45 I.Tr.I. 23 33 n.a.E . 20 20 47 II.Oc.D. Jim 01 19 03 II.Tr.I. 03 46 i.a.E. . 23 52 i.a .i. 21 21 12 III.Oc.D. 02 18 41 i.a .i. 05 01 I.Tr.E. 18 00 46 I.Tr.I. 22 21 13 n.a.E . Auq 23 05 17 I.Tr.I. 10 02 12 I.OC.R. 01 26 II.Tr.E. 23 22 10 I.Tr.I. 26 06 06 n.a.E . 03 26 m .a.E . 02 08 i.a.E. 23 27 I.Sh.I. Sep 02 05 51 n .a .i. 05 01 III.Tr.I. 03 03 I.Tr.E. 24 19 30 I.OC.D. 03 04 54 III.Oc.R. 14 02 43 II.Ec.D. 19 00 16 I.Oc.R. 23 03 I.Ec.R. 07 05 36 I.Ec.D. 04 43 IV.Oc.D. 22 23 43 m .a .i. 25 18 52 I.Tr.E. 08" 06 04 I.Tr.E. 16 02 23 II.Tr.E. 23 03 04 III.Tr.I. 19 31 III.Sh.E. 10 05 41 III.Ec.R. 03 23 i.a .i. 03 16 m .a.E . 20 10 I.Sh.E. 05 45 III.Oc.D. 04 37 I.Tr.I. 04 47 II.Ec.D. 27 23 24 II.Oc.D. 15 04 50 i.a .i. 17 00 31 I.Ec.D. 24 04 28 I.EC.D. 29 21 07 Il.Sh.l. 05 46 I.Tr.I. 03 55 m .a .i. 23 15 n .a .i . 21 13 II.Tr.E. 16 05 12 I.Oc.R. 04 04 I.OC.R. 25 00 53 II.Tr.I. 31 21 26 I.Oc.D. 20 05 08 II.Tr.E. 18 01 21 I.Tr.E. 01 45 i.a .i. Apt 01 19 51 I.Sh.I. 21 03 42 III.Tr.E. 21 02 29 III.Oc.R. 02 09 n.a.E . 20 22 IlI.Sh.I. 23 03 51 I.Ec.D. 05 17 II.Ec.D. 02 32 I.Tr.I. 20 49 I.Tr.E. 24 03 29 I.Sh.E. 22 03 06 iv .a.i. 03 47 II.Tr.E. 22 06 I.Sh.E. 04 31 I.Tr.E. 23 02 01 II.Tr.I. 04 02 i.a.E. 02 19 27 I.Ec.R. 27 05 01 II.Tr.I. 02 27 n.a.E . 04 49 I.Tr.E. 05 21 13 II.Tr.I. 05 43 n.a.E . 04 55 II.Tr.E. 22 19 IV.Tr.I, 07 20 42 II.Ec.R. 28 03 36 m .a.E . 05 16 i.a .i. 22 56 I.Ec.D. 08 19 19 III.Tr.I. 04 28 III.Tr.I. 24 02 24 I.Ec.D. 26 02 02 I.Oc.R. 20 32 I.Tr.I. 30 05 45 I.Ec.D. 23 49 II.Oc.R. 03 03 IV.Tr.E. 21 47 I.Sh.I. Oct 01 03 06 i.a .i. 25 00 55 I.Tr.I. 22 27 II.Oc.R. 22 23 III.Tr.E. 04 12 I.Tr.I. 02 00 i.a.E. 22 30 i.a.E. 09 21 22 I.Ec.R. 05 22 i.a.E. 03 11 I.Tr.E. 23 15 I.Tr.E. 22 26 IV.EC.D. 02 03 38 I.Oc.R. 26 00 23 I.Oc.R. 30 03 40 m .a .i. 16 19 49 I.Oc.D. 04 05 28 Il.Sh.l. 28 01 25 III.Ec.R. 17 19 14 I.Tr.E. 05 04 07 III.Sh.1. 02 37 III.Oc.D. 24
THE CHANGING CONFIGURATIONS OF JUPITER'S MOONS
The 4 bright moons of Jupiter always appear close to a straight line passing through the planet since their orbits are seen nearly edge on. The main part of the diagram shows how their positions along such a straight line change during the 8 months when Jupiter is prominent. For each month, time increases downward; the disc of Jupiter is stretched to make the central column, and horizontal lines representing 2 am (0 hours Universal time), are shown for every day of the month. The wavy lines show how the moons appear to ossilate from each side of the planet to the other.
JANUARY FEBRUARY MARCH APRIL 25
SEPTEMBER OCTOBER NOVEMBER DECEMBER 26
THK MOONS OF SATURN
Saturn's moons are considerably fainter than the 4 Galilean moons of Jupiter. The diagram shows the orbits of 4 of Saturn's moons. The easiest to find is Titan (magnitude +8.5),according to the diagram and information in the table below.
North
TITAN Eastern Elongation Inferior Conjunction Western Elongation Superior Conjunction d h d h d h d h Jan 4 23.9 Jan 8 23.5 Jan 12 18.9 Jan 16 19.6 21 00.8 25 00.2 28 19.6 Feb 1 20.5 Feb 6 01.6 Feb 10 00.8 Feb 13 20.2 17 21.2 22 02.2 26 01.2 Mar 1 20.5 Mar 5 21.6 Mar 10 02.5 Mar 14 01.4 17 20.6 21 21.7 26 02.5 30 01.2 Apr 2 20.4 Apr 6 21.4 Apr 11 02.1 Apr 15 00.6 18 19.7 22 20.7 27 01.2 30 23.5 May 4 18.6 May 8 19.5 May 12 23.9 May 16 22.1 20 17.0 24 17.8 78 22.1 Jun 1 20.3 Jun 5 15.1 Jun 9 15.7 Jun 13 19.9 17 18.1 21 12.8 25 13.2 29 17.4 Jul 3 15.6 Jul 7 10.3 Jul 11 10.6 Jul 15 14.8 19 13.1 23 07.7 27 07.9 31 12.2 Aug 4 10.6 Aug 8 05.2 Aug 12 05.4 Aug 16 09.7 20 08.3 24 03.0 28 03.2 Sep 1 07.6 Sep 5 06.4 Sep 9 01.1 Sep 13 01.4 17 05.9 21 04.8 24 23.7 29 00.0 Oct 3 04.7 Oct 7 03.7 Oct 10 22.7 Oct 14 23.2 19 04.0 23 03.1 26 22.2 30 22.8 Nov 4 03.8 Nov 8 02.8 Nov 11 22.0 Nov 15 22.9 20 03.9 24 02.9 27 22.2 Dec 1 23.3 Dec 6 04.3 Dec 10 03.3 Dec 13 22.6 17 23.9 22 05.0 26 03.8 29 23.3 27
COMETS AND METEORS
COMETS A typical comet consists of a solid nucleous surrounded by a very large envelope of gas and dust, called the coma; in some instances, comets might develop a tail. Depending on the length of their periods around the Sun, comets are classed into 2 groups: Short-period comets, with an average of a 7 year period, an orbital inclination of about 13 degrees and small orbital eccentricities, (0.2 to 0.9) and usually travel in a direct motion; Long-period comets have a period greater than 200 years, random orbital inclinations and about 0.9999 eccentricity and random motion.
About a dozen comets are observed each year and of these, 5 or 6 are new discoveries. As a comet approaches or moves away from the Sun its visual appearance changes drastically and it might become bright enough to be observed with modest equipment such as a good pair of binoculars or a telescope with an aperture not less than 75mra; on rare occasions a very bright comet may become visible to the naked-eye.
Interested observers can contribute with valuable information by reporting on their visual appearance such as coma magnitude, apparent diameter and degree of condensation; if the comet sports a tail, its length in degrees and its p.a. (position angle) should also be reported, as well as the type of instrument and magnification used.
Another area much in need of observers, is that of regularly conducting visual searches of possible new comets, namely in the southern celestial hemisphere. Interested members are asked to contact the Director of the Comet and Meteor Section: Jose Campos, 19 Fiskaal Place, Woodhaven, Durban 4001.
METEORS Orbiting within the solar system, METEOROIDS often collide with the Earth's atmosphere and as a result, they heat to incandescence by friction with the atmosphere's gaseous molecules and an emission of light takes place due to ionization; while in flight through the atmosphere they are called METEORS and they disintegrate completely. There are two types of meteors: Sporadic ones which may be seen at any time of the night, anywhere in the sky; the shower meteors are associated with known meteor showers that are active during certain times of the year (See Table next page). Bright meteors of visual magnitude equal or greater than that of Venus (-4.0 mag.), are classed as Fireballs and if they explode while in flight, they are termed Bolides. Fireballs of visual magnitude equal or brighter than that of the Full Moon are known to produce debris that when found on the ground are called METEORITES. Interested persons are asked to contact the Director: Jose Campos, 19 Fiskaal Place, Woodhaven, Durban 4001. In the event of Fireballs, please phone 031-423684 at any time. 28 Predicted Heteor Hadiant Date Transit of Conditions Recomended yatch at Hax. Lilits Shover (1950) at Radiant at 2.H.R. Beginninq: Ending: K.A. Dec Haxiiui SAST Alt Haxieun SAST Alt. SAST Alt.
Feb 06-15 Theta Ceataurids 14h20 -44 reb 08 05h05 76 Unfavourable ? OlhOO 40 041)00 70 Har 01-12? Pyxids (ney) 09h00 -35 Har 06 221)02 85 Good 6? 21b00 76 038)15 26 Har 13-1« Corona Australids 16D20 -4« Har 16 04h43 72 Poor 5 OlhOO 44 04h30 71 Har 21-Apr 0» Delta Payonids 20hl0 -65 Har 29? 07b43 55 Good 7 021)00 28 041)00 41 Apr 19-2« April Lyrids 181)08 *33 Apr 22 041)06 28 Favourable 15 031)00 26 051)00 26 Apr 11-Hay 12 Alpha Scorpids 16b00 -22 Hay 03 01hl6 12 Favourable 7 21b00 33 041)30 46 Apr 20-Jul 30 Sco-Sqr Systei 18b00 -30 Jun 14 00029 90 Favourable ? 211)00 45 041)00 44 Apr 21-Hay 12 Eta Aquarids 22h24 -01 Hay 03 07h23 60 favourable 20 041)00 31 051)00 43 Hay 25-Jim 20 Chi Scorpids 16h28 -13 Jun 05 23h30 73 Favourable 6? 191)00 25 04bl0 25 Jim 0Í-16 Sagittarids 20bl6 -35 Jun 11 02D59 85 Poor 4? 218)45 26 058)10 62 dun 08-16 Theta Ophiucbids 17b4« -28 Jun 13 001)23 88 Poor 5? 201)00 M 051)00 30 Jun 10-21 June Lyrids 18h22 +35 Jun 16 00b53 25 Favourable 8 238)30 22 018)30 2« Jun 17-26 Ophiuchids 17h20 -20 Jun 20 23h22 80 Good 10 19h00 30 03h30 35 JUil 26-29 Cetids (ney) 02h00 -15 Jun 28 071x35 75 Favourable ? 031)00 25 05h20 56 Jul 10-Auq 05 Capricornids 21b00 -15 Jul 26 001)47 75 Good 8 201)30 30 051)15 25 Jul 14-Auq 25 Horth Delta Aquarids 228x36 -05 Auq 12 01bl3 65 Unfavourable 10 211)00 26 041)30 37 Jul 15-Aug 10 Alpha Capricornids 20h36 -10 Jul 30 231)41 70 Very qood 10 201)00 33 041)00 29 Jul 15-Auq 20 Piscis Australids 22h40 -30 Jul 31 021)03 89 Very qood 12 21D30 32 051)00 51 Jul 15-Aug 25 South Iota Aquarids 22hl3 -15 Auq 05 011)29 75 Unfavourable 12 221)00 40 04(100 52 Jul 15-Sep 20 Horth Iota Aquarids 21h48 -06 Auq 20 231151 66 Very qood 10 201)00 31 041)00 28 Jul 21-Auq 29 South Delta Aquarids 22hl2 -17 Jul 29 021)07 77 Very qood 40 22h00 33 05h00 47 Sep 15-Hoy 26 Southern Taurids 03h22 *14 Hoy 03 001)31 46 Unfavourable 5 21b30 28 031)00 3« Sep 19-Dec 01 northern Taurids 03h53 *22 Hov 13 00h27 3« Favourable 10 238)30 36 OlhOO 37 Oct 02-Hoy 07 Orionids 06h24 *15 oct 21 04h23 45 Good 20 02b00 33 031)50 44 Hoy 14-20 Leonids 10b08 *22 Hov 17 061)21 38 Favourable 10 031)00 18 03b30 23 Dec 03-05 Decenber Phoenicids OlhOO -55 Dec 05 201)07 65 Favourable 5 19b«5 65 OlhOO 33 Dec 04-16 Geiinids 07h28 +32 Dec 14 01h55 28 Favourable 50 238)30 19 031)00 26 Dec 05-Jan 07 Velaids 09D56 -51 Dec 29 03h25 69 Unfavourable 15? 001)30 58 03h30 69
NOTE: The times (SAST) and the altitudes (Alt in degrees) given, are for an observer stationed at E 30.5 S 29.5 (Durban). The Zenith Hourly Rate (ZHR) is the no. of meteors seen by an experienced observer during 1 hour, with a naked-eye limiting magnitude of +6.5 and the radiant in the zenith. 29
MINOR PI^ANET OCCULTATIONS .
A number of A.S.S.A. members and professional observatories form part of a worldwide network which observes the above events. The observations are very useful to astronomers who study the Solar System.
Often an amateur is located on or near an occultation path, and the observation which he or she can make may be of considerable value. The equipment requirements are modest. A 60ram telescope and means to record the time of multiple events will suffice in some instances. The timing equipment comprises a tape recorder tuned to ZUO, WWV or an ordinary FM station as advised by one of the regional co-ordinators listed below. If a continuous time signal cannot be received reliably, then an assistant can read off time intervals of, say, ten seconds from a quartz watch synchronised with the SABC "six pips" time signal. The commentary of the observer and timekeeper is thus recorded for later analysis.
From time to time instructions will be sent to observers wishing to participate in the programme. These will assist observers to locate and identify the occulted s t ars.
If you are in touch with one of the A.S.S.A. Centres and would like to participate, then you are invited to contact one of the conveners listed below. If you do not live near a Centre, then please contact M.D. Overbeek, P 0 Box 212, Edenvale, 1610. Tel Oil 535447. Further updated information may also be obtained from him.
Local Conveners: CAPE TOWN P van Blommestein, 4 Belmont Road, Simons Town, 7995. PIETERMARITZBURG Mr C S Lake, Budleigh Road, Winterskloof, 3240. WITWATERSRAND M D Overbeek, P 0 Box 212, Edenvale, 1610. HARARE J Vincent, 2 Dungarvan Flats, Willson Ave., Borrowdale, Harare. DURBAN R K Field, 303 Wakesleigh Road, Bellair, 4094. PRETORIA Dr J Smit, Dickinsonrylaan 1183, Waverley, 0186.
The Editor regrets that information on possible events during 1990 was not available at the time of publication. 30
Tlie Stars
CONSTELLATIONS Apart from our Sun all the stars that we see are so incredibly distant that, despite their high speed velocities, their apparent positions change by only minute amounts each year. Consequently the patterns that they form appear unchanged. The Greeks and other ancient civilisations identified these patterns, or constellations, with various mythological characters and creatures, and most of the names they gave are still used today. In all there are 88 constellations, roughly one half of which would be above the horizon at any one time. Some contain distinctive patterns of bright stars and are relatively easy to find; others are difficult to locate, even with suitable maps. The Southern Cross and Centaurus, Orion and Taurus, Scorpius and Sagittarius, are featured later in this section. Detailed information on other constellations is beyond the scope of this handbook and interested observers are advised to obtain a suitable star atlas.
STAR NAMES Within each constellation, the brightest star is generally labelled a (Alpha), the next B (Beta) and so on through the Greek alphabet. Most of the brightest stars also have their own names - usually of arable origin. For example a Cants Majoris, otherwise known as Sirius, is the brightest star in the constellation Canis Major.
STELLAR MAGNITUDES The apparent brightness of a star - which depends both on its true luminosity and its distance - is indicated by its magnitude. Equal intervals of magnitude represent equal ratios in light intensity. A star of magnitude 1,0 (typical of the brightest stars in the night sky) would be exactly one hundred times more luminous than a star of magnitude 6,0 (about the limit of visibility to the naked eye). The maps in this section show stars down to magnitude 4,5.
STELLAR DISTANCES Distances are often expressed in units of light years - the distance light would travel in a year (equal to 9,5 x 1012km). DOUBLE STARS It now appears that single stars such as our Sun are the exception, the majority of stars being double or multiple - two or more suns in orbit around one another.
STAR CLUSTERS These are two completely different sorts. Galactic clusters, having of the order of 100 stars, are found close to the plane of the Milky Wav. The ones we can see are relatively nearby. Globular clusters are much larger and far more distant. They contain of the order of 100 000 stars each and are seen above and below the Milky Way on that side of the sky towards the centre of our galaxy. So great is their distance that small telescopes fail to resolve individual stars - instead they appear as fuzzy balls.
NEBULAE Possibly one third of the matter in our region of the Galaxy is in the form of gas and dust (the remainder being contained in stars, plus a tiny amount in planets). Condensations of this material are called nebulae, some of which are illuminated by nearby stars while others are dark. They are usually referred to by their numbers in Messier's catalogue (M) or the New General Catalogue (NGC).
THREE POPULAR REGIONS The dominating constellation of the summer skies is Orion, that of the winter skies is Scorpius, while the Southern Cross is conspicuous for most of the year. The regions around these constellations are also rich in interesting objects - visible either to the naked eye, or with the aid of binoculars or small telescope - and are featured in the maps and text below. It mav be necessary to rotate the maps to match the orientation of the constellations in the sky. 31
THE ORION REGION
© • Riger^A
CAMS •
'•.TAURUS y •* MAJOR Hyadcs * • G reat Nebula Pleiades , \ @ u , ya © •* : m Aldebaran (©-Siriu.c £ * © ORION
- >^ Betelgeuse
, " TC'Crab rab Nebula K V M 1 L
© .
(T) The constellation of Orion. The figure of the legendary hunter of Greek mythology Is unfortunately upside down when seen from Southern Africa. The faint stars by X represent the head, a and Y the shoulders, 6 - e - n the belt, and P and k the legs. Orion forms part of the "great hunting scene" in which he faces the onslaught of ( 2 ) Taurus, the bull. Only the forepart of the bull is depicted and, like Orion, it is upside down, a and e are the eyes, Y the noso. Orion is accompanied by Canis major, the large dog, and the small dog (off map) while Lepus, the hare, crouches at his feet.
( 4 ) A section of the .Ecliptic - a line encircling tho entire sky and representing the plane of the Earth’s orbit. As the Earth rovolves around the Sun, the Sun appears to move along the ecliptic through the constellations of the Zodiac, of which Taurus is one.
( 5 ) A portion of the Milky Way (looking out towards the edge of our Galaxy). © Sirius - the brightest star in the night sky. It is somewhat brighter than our Sun and relatively close by - at a distance of 9 light years. It is a double star but the companion is a white dwarf (only slightly larger than the Earth, and with a mass comparable to our Sun ) and is only visible through a large telescope.
( t) Betelgeuse - most famous of the red giant stars. Its diameter is of the order of the size of the Earth’s orbit and its luminosity is nearly 10 000 limes that of our Sun. Its red colour should be obvious to the eye. It is 520 light years distant. © Rigel, despite being physically smaller than Betelgeuse, is more luminous (higher surface temperature - bluish colour) and more distant.
( 9 ) The stars in Orion’s belt are distant hot blue stars.
(19) The Pleiades or Seven Sisters form the best known nearby star cluster. Six or seven stars are visible to the naked eye, binoculars or a small telescope show more. (ÍÍ) The Hyades is another nearby galactic cluster, but Aldebaran is not a member (it lies closer to us).
( £ 2) The Great Nebula in Orion, just visible to the naked eye, shows up as a fan shaped mass of luminous gas through binoculars or a telescope. A telescope will also show a liny "Trapezium" of four stars in the centre. © The Crab Nebula, the remnant of a supernova recorded by the Chinese in 1054, requires a moderate sized telescope for observation. Jn its heart is located the extraodinary pulsar which emits a double flash of light 30 times every second. The current belief is that it is a rapidly rotating neutron star - a star with the mass of our sun but with a diameter of only 10 km. 32
Crux, the Southern Cross, is one of the most compact patterns of bright stars to be found In the sky. It lies on the border of that region of the sky which never sets as seen from Southern Africa.
( 2) The two ’’Pointer" stars lie close to the Cross. (A similar pattern to the Southern Cross - called the false Cross - lies just outside and above the map, but has no accompanying pointer stars).
( 3) The South Celestial Pole: This is one of two opposite.points in space towards which the Earth’s axis of rotation is directed. As the Earth rotates so the sky appears to pivot about this point. It always lies above the south point on the horizon, elevated by an angle equal to the observer’s southern latitude. (The north celestial pole lies below the northern horizon and can never be seen from the Earth's southern hemisphere) (T) The intersection of a line extended through the major axis of the Cross and the perpendicular bisector to the Pointers indicates the approximate position of the South Celestial Pole.
( 5) a Centauri has the distinction of being the closest star to our solar system - at a distance of approximately 40 million million km or 4,3 light years. A small telescope readily shows that it is a double star - the two components take 80 years to revolve about one another. A much fainter third star also belongs to the system. (jT) a Crucis can also be resolved as a double star by a small telescope {separation 5 sec of arc). © The region indicated is one of the brightest sections of the entire Milky Way. (8) The Large and Small Magellanic Clouds are the nearest of the external galaxies (see also next section). They can be seen with the naked eye provided the sky is reasonably dark.
( 9) The Great Looped Nebula - possibly the remnant of a supernova explosion - in the Large Magellanic Cloud. (Naked eye or binoculars). The "Coal Sack" - á dark mass of gas and dust obscuring a part of the Milky Way. (Naked eye or bino culars). Herschel’s "Jewel Box” - a galactic cluster contáíning stars of different colours. (Small telescope or binoculars).
(l^ w Centauri and ( £ $ ) 47 Tucanae are perhaps the best known globular clusters. Binoculars will show their fuzzy appearance. (£$) NGC 362 and @ NGC 2908 are fainter globular clusters. (l^ NGC 3760 - a fine galactic cluster. (Binoculars or small telescope). @ The n Carinae nebula - site of a slow supernova that brightened to magnitude -0,8 in 1843 and is now of magnitude 6,4. 33
THE SCORPIUS REGION
(T) The constellation of Scorpius. The creature is depicted with a in the centre of the body and S and ?i the claws. The distinctive tail e — c — 6 curls round to the sting X.
( 2) Sagittarius - the figure of the centaur archer is very difficult to make out.
( 3) A section of the Ecliptic. Like Taurus, Scorpius and Sagittarius are constellations of the Zodiac.
( 4) The direction of the centre of our Galaxy - the Milky Way is that part of our Galaxy visible to us. Un fortunately the central nucleus is obscured by foreground gaseous and dusty matter - both dark and luminous - hence the irregular shape of the Milky Way in this region. Luminous nebulae include @ the Lagoon nebula and (fT) the Omega nebula. These are best seen with the aid of binoculars. (j) Antares - a distant red giant, several hundred times the diameter of our Sun - is so named because its red colour rivals that of the planet Mars. (jT) £ Scorpii can be resolved as a double star (separation 16 sec of arc) with a small telescope. In fact the brighter component is in itself a triple star, and the fainter component a double star'.
This region includes a number of galactic clusters including M7, M8, M4 and (T£) NGC 6067. (Use binoculars or a sm all telescope).
Further from the plane of the Milky Way are some globular clusters: M 80 @ M19 and @ M22. 34
VARIABLE STAR OBSERVING The latest (1985) edition of the "General Catalogue of Variable Stars" lists more than 28 000 stars. Professional observatories cannot possibly monitor all of these, and this makes the observation of variable stars a field in which amateurs can make a real contribution to astronomical knowledge.
Of these 28 000 stars at least 2 000 are suitable for visual monitoring in the southern hemisphere. However, the number of active observers in this part of the world remains woefully small, and less than 400 variables are at present being observed from Southern Africa.
The Variable Star Section of the A.S.S.A. exists for the purpose of encouraging observers and of acting as a medium communication. The Section disseminates incoming information amongst observers, and will forward (on request) the observations of individuals to various variable star bodies. These include the American Association of the Variable Star Observers (AAVSO) and the Variable Star Section of the Royal Astronomical Society of New Zealand. These bodies combine the South African light estimates with those from other parts of the world. The resulting "light curves" and tables are made available to a large number of professional observatories where astronomers are interested in investigating certain of the stars more fully. / In recent years amateur observers have played an invaluable part by alerting the operators of orbiting satellite observatories whenever outburst occurred of certain eruptive variables.
Visual estimates of magnitude are made by comparing the variable with two or more comparison stars, respectively brighter and fainter than the unknown variable. Suitable comparison stars are shown on special charts, which have been prepared for each variable, mainly by the two variable star organisations mentioned above. The use of these charts is essential for accurate, standardized observations and intending new observers are therefore advised to obtain the necessary data by contacting the Director of the Variable Star Section, Mr. J. Hers, P.0. Box 48, Sedgefield, 6573, Telephone (04455) 31736. They will then be sent charts of a few easy objects and data on stars which may be observed with the equipment at their disposal.
Prospective observers should, when writing, give brief details of their equipment. Larger, more powerful telescopes will naturally greatly increase the number of stars which may be measured, but many variables are bright enough to be observed through most of their cycles with quite modest equipment, e.g. binoculars. Some stars, such as 071044 L2 Puppis, are so bright that they may be observed without optical aid whatever.
Variable stars are designated in two ways. The first of these, the Harvard designation, consists of six figures which give the position for 1900; the first four figures give hours and minutes of R.A., the last two give the declination in degrees, underlined for southern declinations. The second name consists of one or two letters (or letter V plus a number) and the name of constellation.
Variables can be divided into three main classes: pulsating, eruptive and eclipsing binary stars.
Most suitable for beginners are the long period variables (or Mira variables, named after the typical representative Mira - o Ceti) which belongs to the class of pulsating stars. They are giant stars which vary through a range of brightness of 2.5 to 5 magnitudes or more, and which have well defined periodicities, ranging from 80 to 1000 days. In most cases one observation per observer every 10 days will suffice. 35
Typical examples include: Approximate magnitude range 021401 o Ceti(Mira) 2.0-10.1
092962 R Carinae 3.9-10.0
1006£i S Carinae 4.5-9.9
Among the eruptive variables, two groups are of special importance:
U Geminorum type. These are dwarf novae which have long periods of apparent quiescence at minimum, with sudden rises to maximum. A typical representative in the southern hemisphere is 040971 VW Hydri.
R. Coronae Borealis type These are high luminosity variables with slow, non-pcriodic drops in brightness. A typical representative is 191033 RY Sagittarii.
Eclipsing. Binary Stars have orbital planes which lie close to the line of sight of the observer. The two components periodically eclipse each other, thus causing variations in the apparent brightness of the system. Periods are generally short, of the order of hours, so that observational programmes need very careful planning. Monitoring these interesting stars is therefore for experienced observers only.
NOVA SEARCHING On rare occasions a star may undergo a nova outburst, its light increasing tremendously. The result is that a "new" star appears where previously no star was visible to the naked eye, or even with a small telescope. The light of the nova may fluctuate for a time, then gradually fades over a period of days, weeks or m o n t h s . Even observers having no telescopes can perform a useful task in keeping a watch for such novae in an allocated area of the sky. A good knowledge of the constellations is a recommendation, since part of the procedure is to scan the whole sky for bright novae before the more detailed search in the allocated area is begun. However, anyone can be given training in star recognition. 36
ORDXNARY OCCULTATX ONS
This Section and that following concern a specialised branch of observational astronony in which both professional and amateur participate. The tables of predictions roust necessarily occupy a number of pages as this handbook is the sole published source for Southern Africa.
An occultation occurs when the disk of the Moon moves in front of a star. Timings of occultations, to a precision of one-tenth of a second if possible are very valuable for studies of the Moon's shape and motion. Since only very modest equipment is required, amateurs can make important contributions in this field. Persons interested in making and reporting occultation observations are urged to contact the Director of the society's Occultation Section: Mr. M.D. Overbeek, P.0. Box 212,Edenvale, 1610 Tel: (Oil) 535 447
Predictions of occultations of all stars brighter than magnitude 7,5 supplied by Hydrographic Dept.,Tokyo are given below.The main set of tables give predictions for three stations,namely: Longitude Latitude Cape Town 18°.475 E 33°.933 S Johannesburg 28°.075 E 26°.182 S Harare 31°.100 E 17°.800 S
This does not restrict its use to observers in those centres. The approximate time of an occultation at a place A A degrees west and A
Occulted stars have been identified by their Z.C. numbers, that is their numbers in the "Catalogue of 3539 Zodiacal Stars for the Equinox 1950.0" by James Robertson (U S Naval Observatory, 1939).
Note: That the times of these occul tations are given in U.T.
EXPLANATIONS OF ABBREVIATIONS USED IN THE TABLES:
Z.C. the number of the star in the Zodiacal Catalogue. An "ra" following the number indicates the star is not single, Mag. the visual magnitude Ph the Phase: D - Disappearance, R * Reappearance h.m. the time of the occultation in UT a,b parameters in minutes for predicting times other than at standard stations (as explained above in the text) P . A. The Position Angle on the Moon's limb measured eastward from the north point 37
CAPE TOWN JOHANNESBURG HARARE OT 18.5 S 33.' E 28.1 S 26.2 31.0 S 17.8 DATE s.c. Xaq. Hi ELG TINE a. b. P.A. TINE a. b. P.A. TINE a. b. P.A X D ' h ■ a ■ ' h ■ ■ i ' h » n g ‘ Jan 1 3308 6.2 DD 56 18 54.3 -0.6 +1.7 66 19 10.3 -0.2 +1.5 60 Jan 1 3311 7.0 H> 56 19 34.1 -0.5 +1.3 87 Jan 8 771» 6.1 DD 150 23 33.3 -1.0 +0.2 119 23 48.0 -1.2 +0.9 86 24 3.4 -1.8 +2.0 54 Jan 13 1466» 5.2 RD 214 21 18.2 -0.9 -2.8 343 Jan 14 1567 6.3 RD 226 22 13.2 -1.1 -1.7 294 22 9.7 -1.2 -2.1 316 21 52.4 -0.9 -2.9 339
Jan 18 1970» 6.2 RD 271 23 34.7 -0.9 -0.6 247 23 34.9 -0.7 -1.3 280 23 24.5 -0.4 -1.6 303 Jan 20 2084 6.5 RD 282 1 0.9 -2.6 +0.5 242 1 2.9 -1.4 -0.9 277 Jan 22 2366» 1.2 DB 307 7 45.2 -2.7 +2.8 54 Jan 22 2366» 1.2 RD 308 3 56.2 -2.6 -2.2 318 Feb 1 243 6.9 DC 76 17 40.5 -1.7 +1.7 53 18 2.2 -1.5 +2.4 34
Feb 1 245 6.1 DD 76 17 50.5 -2.0 +0.1 109 17 59.7 -1.7 +0.7 87 Feb 2 390 5.4 DO 90 19 4.9 -1.7 +1.4 67 19 32.9 -1.5 +1.9 50 19 59.1 -1.9 +3.8 18 Feb 3 529 6.2 DD 104 20 48.3 -0.4 -0.8 128 Feb 5 885 5.7 DD 131 22 20.9 -0.8 -0.2 131 22 31.9 -1.1 +0.6 96 22 44.8 -1.7 +1.7 63 Feb 7 1170» 3.7 DD 154 17 03.4 -0.3 +0.0 52 17 13.2 36
Feb 9 1415 6.2 RD 181 20 33.6 -2.8 -0.8 278 Feb 12 1635 5.4 RD 207 1 40.9 -1.3 -1.5 322 1 26.0 +1.1 -4.9 13 Feb 12 1637 6.0 RD 208 3 6.8 -1.0 -1.0 320 2 53.5 11 Feb 13 1815 4.8 RD 227 20 9.2 +0.1 -2.0 322 19 50.0 +0.2 -2.7 346 Feb 15 2039 5.6 RD 250 22 48.4 13
Feb 16 2045 6.4 RD 251 0 25.0 -0.4 -2.7 330 Feb 16 2051 5.7 RD 251 1 11.6 +0.8 -4.5 1 Feb 17 2268 4.8 RD 272 22 51.4 -1.5 +0.9 236 Feb 17 2273 5.9 RD 272 23 34.6 -1.0 -0.5 256 23 30.0 -0.6 -1.1 285 Feb 20 2558 6.2 RD 296 2 18.9 -0.3 -2.3 305
Feb 22 2872» 6.2 RD 319 2 14.6 -0.4 -0.1 236 2 13.2 -0.2 -1.0 273 2 0.9 +0.4 -2.2 309 Feb 22 2875 6.1 RD 319 2 21.7 -0.4 -0.0 234 2 21.6 -0.3 -0.9 271 2 10.0 +0.2 -2.1 307 Nar 2 490 5.7 DD 73 19 25.7 -0.9 +0.9 99 Har 3 638 5.1 DD 85 16 52.8 24 Nar 7 1269 7.0 DD 137 19 22.7 -2.6 -0.3 86
Nar 7 1277 5.5 DD 139 22 40.7 -1.7 ‘0.6 99 Nar 15 2108» 6.4 RD 230 22 54.5 -2.7 +0.2 244 23 8.5 -1.8 -1.5 290 22 56.6 -1.1 -2.4 318 Nar 15 2109 6.1 RD 231 23 39.1 -3.4 +0.7 243 23 59.2 -2.2 -1.5 291 23 47.7 -1.5 -2.6 321 Nar 17 2366 1.2 DB 252 22 33.1 -0.0 -2.2 133 22 20.3 -0.6 -1.1 105 Nar 17 2366 1.2 RD 252 23 41.0 -1.7 -0.8 267 23 35.0 -1.1 -1.6 297
Nar 18 2373 6.2 RD 253 0 38.5 -3.0 +1.3 231 1 0.6 -2.2 -1.1 279 0 52.2 -1.7 -2.4 311 Nar 31 771» 6.1 DD 68 IS 3.9 -1.7 +1.1 79 18 36.6 37 Nar 31 773 6.9 DD 69 18 44.3 -0.4 -0.2 117 Apr 2 1094 6.9 DD 94 17 8.7 -3.7 +1.7 60 Apr 7 1652» 5.5 DD 153 16 57.9 -0.7 -2.0 125 16 54.2 -1.4 -1.4 103 16 52.1 -2.2 -0.0 76
Apr 17 2767 6.4 RD 257 2 58.3 -2.6 -3.0 304 Apr 17 2771« 5.7 RD 257 4 32.8 -3.2 -1.4 294 Apr 29 1046 6.9 DD 63 16 36.2 +0.7 -3.6 172 Apr 29 1049 6.6 DD 63 17 11.3 175 Apr 29 1055 5.8 DD 64 18 46.9 *0.9 -2.3 165
Nay 1 1321 6.7 DD 89 19 13.6 +0.1 -2.1 167 19 2.7 -0.9 -1.0 133 Nay 2 1425 6.9 DD 101 17 46.8 +0.1 -3.3 179 17 27.7 -1.5 -2.1 147 Nay 2 1427 6.8 DD 101 18 52.2 +0.2 -3.0 178 18 35.3 -1.2 -1.7 143 Nay 3 1539 7.4 DD 114 20 59.6 +0.1 -3.0 176 20 44.3 -0.9 -1.4 139 Nay 3 1549» 5.2 DD 115 23 0.4 -0.9 +1.7 82 38
CAPE TOWN JOHAHNESBCRG HARARE CT 18.5 S 33.9 E 28.1 S 26.2 31.0 S 17.8 DATE !.C. Hag. Ph ELG TIME a. b. P.A. TIHE a. b. P.A. TIKE a. b. P.A. N D * h b B B 5 B b a b a a m Hay 4 1624 6.8 DD 124 18 17.8 -1.8 -1.6 128 18 35.6 -3.9 +0.3 86 Hay 13 2558 6.2 RD 215 1 2.0 -2.4 +7.5 199 1 52.8 -2.1 +2.5 232 2 14.1 -2.4 +1.1 258 Hay 17 3108 5.5 RD 260 0 3.3 -0.9 -0.5 252 0 6.4 -1.4 -1.7 283 Hay 29 1385 6.5 DO 70 15 44.4 -2.1 -0.7 114 16 12.8 -4.3 +2.1 68 Hay 29 1396 7.1 DD 72 19 50.4 -0.4 -0.2 130
Hay 30 1497H 7.5 DD 83 18 14.9 -0.9 -1.4 150 18 21.7 -1.7 -0.0 109 18 36.3 66 Hay 31 1599« 5.1 DD 95 18 21.5 -2.3 -0.1 105 Jun 5 2108 6.4 DD 150 17 8.9 -0.5 -2.7 146 16 53.5 -1.3 -1.7 113 Jan 5 2109 6.1 DD 150 17 56.4 -0.9 -2.8 145 17 42.0 -1.8 -1.6 116 Jun 10 2811 6.2 RD 207 20 56.8 -1.8 +1.6 216 21 18.7 -2.0 -0.1 256 21 17.9 -2.1 -1.6 219
Jun 27 1565 6.3 DD 65 19 2.8 -0.1 -2.0 160 Jun 30 1872 7.3 DD 101 21 3.4 -0.8 -5.4 182 20 54.2 -1.0 -1.1 139 20 52.4 -1.0 -0.1 101 Jul 1 1967 5.7 DD 110 17 29.9 -1.5 -2.4 143 17 38.8 -3.0 -0.6 102 18 0.4 56 Jul 2 2084 6.5 DD 122 19 28.5 -2.6 -0.1 100 20 7.5 -2.9 +4.0 56 Jul 4 2332 6.2 DD 143 18 15.7 -4.0 +3.0 45
Jul 5 2458 6.2 DD 153 17 3.5 -1.2 -0.8 79 Jul 5 2480m 5.3 DD 156 22 55.7 -1.6 +3.0 49 23 32.4 -0.2 +4.1 29 Jul 5 2479b 5.3 I» 156 22 55.8 -1.6 +3.0 48 23 32.7 -0.2 +4.2 29 Jul 9 3017 5.3 RD 200 18 12.1 -0.1 -1.6 287 Jul 11 3285m 6.1 RD 225 21 22.7 -0.8 -1.0 266 21 19.0 -1.6 -3.4 298
JUl 16 266a 5.7 RD 277 00 02.8 -0.1 +0.0 234 0 5.3 -0.5 -0.1 247 0 4.8 -1.1 -0.7 271 Jul 25 1611 5.7 DD 45 15 50.5 -0.4 -2.5 166 Jul 26 1727 7.1 DD 58 18 39.1 -0.7 -0.3 129 18 47.1 -0.5 +0.7 97 Jul 28 1944B 5.7 DD 82 21 7.8 -1.0 -2.9 168 21 2.9 -0.5 -0.8 138 Jul 30 2152 7.3 DD 103 18 52.2 168 18 34.5 -2.6 -1.5 126
Jul 31 2268 4.8 DD 113 16 13.0 -1.1 -3.9 153 15 55.5 -2.3 -1.8 118 Jul 31 2273 5.9 DD 113 16 40.9 -0.9 -3.9 155 16 37.7 -2.5 -1.5 112 16 42.3 -3.7 +0.6 79 Aug l 2420 7.4 I» 125 18 6.4 -2.0 -2.6 130 18 20.0 -3.0 -0.3 95 18 35.9 -3.3 *2.0 63 Aug 2 2558 6.2 DD 137 21 19.7 -3.0 -0.8 113 Aug 3 2719m 5.8 DD 149 22 22.2 +0.3 +6.0 7
Aug 8 3269 4.3 RD 198 2 22.1 -0.3 +2.8 196 2 46.1 -0.1 +2.8 194 3 8.2 -0.3 *2.2 211 Aug 11 221b 3.7 RD 247 22 06.1 -0.2 -0.1 237 22 8.9 -0.7 -0.2 251 22 7.4 -1.3 -0.9 276 Aug 12 245 6.1 RD 250 2 41.4 -0.3 +2.5 186 3 7.3 -0.5 +3.3 185 3 35.4 -1.5 +2.7 204 Aug 15 701b 6.5 RD 289 2 25.4 +0.2 +1.2 205 2 36.3 -0.4 *1.4 211 2 48.3 -1.3 +0.9 231 Aug 22 HERCCRÏ 0.9 DD 24 11 32.3 -0.4 -3.4 173 11 12.5 -1.7 -2.3 143
Aug 22 HERCERÏ 0.9 RB 25 12 39.1 -3.2 +0.4 271 12 42.2 -2.1 -1.3 305 Aug 23 1778 7.1 DD 39 16 24.7 -1.3 +0.3 n o 16 45.3 -1.1 +2.3 71 Aug 26 2108b 6.4 DD 72 16 56.0 -2.6 +2.2 70 Aug 26 2109 6.1 DD 73 17 40.0 -2.0 +1.2 86 18 12.7 -1.1 +3.3 54 Aug 28 2366 1.2 DD 95 17 40.3 -3.0 -2.5 135 17 38.9 -3.0 -0.3 102
Aug 28 2366 1.2 RB 95 18 48.6 -1.3 +3.4 226 19 11.2 -1.5 +1.3 255 Aug 28 2373 6.2 DD 95 19 15.0 -2.8 -2.0 134 Aug 29 2524 6.0 DD 108 22 48.2 +1.0 +3.6 21 23 4.9 8 Aug 30 2657 6.7 DD 117 19 29.9 -2.7 -0.3 104 19 56.5 -2.3 +0.7 90 20 11.7 -1.7 +1.4 69 Aug 30 2672 2.9 DD 119 23 38.4 -0.1 +1.7 64 23 49.7 +0.3 +1.5 60
Aug 31 2678 6.2 DO 120 0 22.9 +0.4 +1.9 49 Aug 31 2672 2.9 RB 120 0 37.7 +0.1 *1.2 261 Aug 31 2803 6.9 DD 128 18 4.9 -3.6 -1.2 105 Aug 31 2811 6.2 DD 129 20 16.7 130 20 17.9 -3.1 -0.1 99 Sep 1 2929 7.1 DD 139 17 15.0 -2.4 -3.1 121 17 10.3 -2.5 -0.2 85 39
CAPE TOMf JOHANNESBORG HARARE or E 18.5 S 33.9 E 28.1 S 26.2 E 31.0 S 17.8 DATE Z.C. Hag. Ph ELG TIKE a. b. P.A. TINE a. b. P.A. TINE a. b. P.A. H D ' b I n " h a a a h a a n Sep 2 2963a 5.5 DD 144 2 31.3 +0.5 +1.9 38 Sep 3 3188 5.4 DD 163 17 9.2 -0.8 +2.9 10 Sep 9 3371 5.7 HD 233 1 18.9 -1.5 +0.9 226 1 44.5 -1.9 +1.5 226 2 2.6 -2.4 +1.3 241 Sep 24 2332 6.2 DD 65 19 33.6 -0.8 +0.7 106 19 44.3 -0.3 +0.7 96 Sep 25 2458 6.2 DD 76 19 5.0 -1.7 +0.3 111 19 21.5 -1.0 +0.6 101 19 30.2 -0.5 +1.0 80
Sep 26 2579 7.3 DD 86 17 16.0 152 Sep 27 2756 7.4 DD 99 21 22.5 145 21 18.4 -1.1 -0.2 112 Sep 29 3022 6.9 DD 122 21 40.7 -0.4 +2.7 29 22 3.1 -0.1 +2.5 29 22 25.3 +0.6 +3.1 10 Sep 30 3142 6.8 DD 132 17 48.4 -2.3 -0.8 90 18 11.4 -2.7 +0.4 77 18 27.4 -2.4 +1.5 57 Sep 30 3155 6.9 DD 134 22 30.8 +0.5 +3.6 360 22 53.1 +0.6 +3.5 0
Oct 1 3269 4.3 1» 144 17 52.0 -1.1 +1.7 30 18 19.5 -0.9 +2.8 16 18 53.5 348 Oct 6 288 5.2 SD 202 1 16.6 175 Oct 11 1099 6.0 RD 269 1 39.9 -1.8 -2.3 319 1 39.2 -2.4 -3.5 337 Oct 21 2269 5.4 DD 34 16 56.0 -0.8 +1.2 89 17 11.3 -0.2 +1.4 76 17 24.8 +0.4 +2.0 52 Oct 24 2672 2.9 DD 65 13 29.2 -2.4 -0.4 85 14 0. -2.8 +1.8 57 14 35.6 -1.7 +5.4 21
Oct 24 2672 2.9 SB 66 15 6.8 -2.6 +0.7 258 15 36.6 -2.9 +0.2 275 15 39.9 -4.4 -2.4 304 Oct 26 29630 5.5 DD 90 19 36.9 -1.3 +1.7 70 19 59.3 -0.8 +1.5 70 20 14.3 -0.4 +1.6 55 Oct 27 3100 6.4 DD 102 21 27.2 -1.3 +1.0 99 21 43.9 -0.7 +0.8 96 21 52.9 -0.3 +1.0 79 Oct 28 3208 6.5 DD 112 17 6.3 -1.2 +3.0 23 Oct 30 3482 5.7 DD 138 19 24.3 -4.7 -2.5 116 19 55.9 122 20 0. -3.6 -0.0 %
Oct 30 3482 5.7 ED 138 20 20.5 157 Hov 4 7011 6.5 RD 210 23 38.5 -2.2 -0.6 281 23 57.5 -2.6 -0.7 292 23 54.5 -3.0 -2.5 318 Nov 5 849 6.5 RD 221 20 9.9 -0.0 +0.8 228 Nov 7 1055 5.8 RD 238 1 46.5 -2.2 -0.7 285 2 1.3 -2.1 -1.1 307 1 52.5 -1.7 -2.8 334 Nov 19 2514 6.3 DD 26 18 13.4 -0.3 +0.6 110
Nov 20 2659 6.4 DD 37 19 11.3 +0.2 +1.4 73 Nov 21 2793 6.5 DD 47 17 22.5 *0.3 +2.9 25 17 50.0 355 Nov 23 3036 7.0 DD 69 17 12.7 -1.0 +2.2 45 Nov 29 266 5.7 DD 143 16 40.9 -1.3 +0.6 60 Dec 9 1611 5.7 RD 270 2 35.3 -3.2 -0.4 266 2 35.7 -2.4 -1.4 295
Dec 19 SATCRN 0.6 DD 27 16 40.8 -1.2 -0.3 113 Dec 19 SATCRN 0.6 RB 28 17 21.4 +0.9+2.8 195 Dec 19 2892 6.8 DD 28 17 55.4 -0.2 +0.6 102 Dec 20 3011 7.0 DD 39 18 10.0 -0.8 *1.0 99 18 22.0 -0.3 +0.8 94 Dec 21 3131 5.5 DD 50 17 32.0 -4.1 -1.9 130 17 50.9 126 17 53.9 -1.1 +0.3 100
Dec 21 3137 6.7 DD 51 19 10.2 +0.1 +2.4 26 Dec 22 3248 6.6 DD 61 17 34.0 -0.1 +3.0 14 Dec 23 3371 6.4 DD 74 18 51.8 -0.3 +3.0 10 19 17.6 -0.0 +3.4 3 Dec 28 518 5.9 DD 140 23 33.6 -0.0 -0.9 138 23 32.2 -0.6 +0.1 105 Dec 29 701 6.5 DD 153 21 52.3 -2.1 +0.8 70 22 24.9 -2.5 +2.2 45 4 0
GRAZING OCCTJLT AT I ONS
When a star moves tangentially to the limb of the Moon, and is occulted for a very short period only - a few minutes, or even seconds - a grazing occultation is said to occur. Because the limb, as seen from the Earth, is in fact the outline of numerous mountains and valleys, there may be several disappearances and reappearances, which are not only fascinating to observe, but which may be accurately timed to yield valuable data on the relative positions of star and Moon, as well as on the shape of the Moon. Some of this data cannot readily be obtained in any other way. The maps on the following pages have been prepared by the Hydrographic Dept., Tokyo to show the tracks of stars brighter than 7.5 magnitude which will graze the limb of the Moon when it is at a favourable elongation from the Sun and at least 10° above the observer's horizon (2° in the case of bright stars). Each track starts in the west at some arbitrary time given in the key and ends beyond the area of interest, except where the Moon is at a low altitude, the bright limb or sunlight interferes. The tracks as shown on the maps are approximate only. Since the observer's location is very critical, successful observations call for very accurate predictions. Such predictions, which include graphical representations of the probable profile of the Moon, are computed annually for a number of centres in Southern Africa. By plotting the predicted graze track on a reliable survey map (e.g.South African 1:50 000 series) it is usually possible to select a convenient site from where the graze may be observed. Ideally a team of observers would be stationed at intervals along a line running at right angles to the graze track - say,along a main road - each with his own telescope and timing equipment. Each observer will see a different sequence of events, the combined results forming an accurate picture of the limb of the Moon. The equipment needed is similar to that used for ordinary or "total" occultations, but must, of course, be portable. A 75 mum refractor is ideal for average events, but instruments with a larger aperture have often shown their superiority under difficult conditions. Timing is best carried out with a portable tape recorder and radio receiver tuned to ZU0 or other time signal station. It will be seen from the maps that many grazing occultations occur in regions which are rather far removed from the main cities, and which cannot easily be reached by teams of observers from one of the ASSA centres. It is worth remembering, however, that a team of many observers.while ideal, is by no means essential, that a single good observer is worth more than many unsuccessful ones, and that one good observation is worth infinitely more than no observation at all. Interested observers - especially those living in the more distant regions - who wish to be informed of favourable grazes occurring in their neighbourhood, are therefore invited to contact the co-ordinator for grazing occultations: Mr.M.D. Overbeek, P.0. Box 212, Edenvale, 1610. Tel: (011) 535 447.
EXPLANATION OF THE COLUMN HEADINGS IN THE TABLES: SEQ : Sequential number in the year. The same number is attached to the corresponding track on the map. NZC NO : Zodiacal Catalogue number of the star. MAG : Magnitude of the star. MON, DAY, H, M, S : Month, day, hour, minute and second in SAST for the west end of the track. SUNLIT (X) : Percentage of the Moon sunlit (a minus sign indicates a waning Moon). LIMIT : Whether the track is the north (N) or the south (S) limit of the occultation. (A) denotes that the Moon is at a low altitude. (B) denotes that the star is occultated at bright limb. (S) denotes that the daylight interferes. The map gives the graze tracks or the limits of occultations. Along each track on the map tick marks are qiven for the points corresponding to the multiples of five minutes of every hour, while the prediction for the west end of each track is shown in the table, e.g.if the time for the west end of a track is 5h 43m 21s, the tick marks proceeding eastward correspond to 5h 45m 00s, 5h 50m 00s, 5h 55m 00s e t c . YEAR 1990 MONTH 1 - 3 ( 1-17 )
SEQ NZC NO MAG MON DAY H M S SUNLIT(X) LIMIT 1 3420 7.14 1 2 18 43 37.01 30.54 S (S) ( ) 2 288 5.16 1 5 21 59 26.37 65.46 S ( ) ( ) 3 569 5.38 1 7 18 20 51.84 84.35 S IS) ( ) 4 1685 4.47 1 16 4 35 16.65 -75.50 S ( ) ( ) 5 2084 6.48 1 20 2 24 30.31 -38.71 S ( ) ( ) 6 2366 1.22 1 22 9 54 21.55 -19.61 N ( ) ( ) 7 1944 5.65 2 15 5 2 16.71 -74.23 S ( ) (S) 8 2152 7.34 2 17 2 23 23.63 -56.71 s ( ) ( ) 9 2268 4.82 2 18 0 33 15.63 -47.74 s ( ) ( ) 10 2273 5.93 2 18 1 9 23.80 -47.58 s (A) ( ) 11 1013 6.89 3 6 0 2 35.92 69.33 N ( ) (A) 12 2366 1.22 3 18 0 59 46.53 -64.85 S ( ) ( ) 13 2373 6.22 3 18 2 7 14.88 -64.52 s ( ) ( ) 14 2512 7.44 3 19 2 29 0.20 -54.93 s ( ) ( ) 15 2823 6.95 3 21 5 16 10.09 -34.55 N (B) (S) 16 768 7.00 3 31 19 49 48.50 31.11 N ( ) ( ) 17 771 6.13 3 31 20 42 20.73 31.24 N ( ) (A) 42
SEQ NZC NO HAG MON DAY H H S SUNLIT(%) LIMIT 18 1094 6.89 4 2 19 10 5 .06 53.03 N < ) < ) 19 2767 6.38 4 17 4 1 35 .21 -61.41 N ( ) (S) 20 2771 5.73 4 17 5 34 25 .01 -61.07 N ( ) (S) 21 3294 6.89 4 21 4 0 4 . 75 -21.44 N (A) ( ) 22 1322 6.14 5 1 20 13 44 .04 48.77 N ( ) ( ) 23 1525 5.92 5 3 17 51 36 .31 68.49 N (S) ( ) 24 1549 5.17 5 4 1 18 37 . 78 70.49 N ( ) (A) 25 2977 6.88 5 16 1 14 33 .41 -67.92 N (E) ( ) 26 3108 5.50 5 17 1 21 58..25 -57.98 N (B) ( ) 27 3366 6.61 5 19 3 36 34..22 -35.93 N ( ) ( ) 28 1385 6.49 5 29 18 17 59..82 32.59 N (S) ( ) 29 1599 5.05 5 31 20 19 39. 10 54.04 N ( ) ( ) 30 2366 1.22 6 7 20 14 21. 48 99.49 S ( ) ( ) 31 3328 7.04 6 15 2 57 46. 66 -61.77 N ( ) ( ) 32 191 7.36 6 18 6 9 48. 89 -27.77 N ( ) (S) 33 329 7.10 6 19 5 56 37. 26 -17.93 N ( ) (S) 34 1345 7.11 6 25 19 30 43-. 69 11.03 N ( ) ( ) 35 1448 6.66 6 26 17 59 24. 57 18.40 N (S) ( ) 43
YEAR 1990 MONTH 7-9 ( 3 6 - 5 3 )
-2 0
-30
SEQ SZC NO MAG MON DAY il M 5 SUNLIT(t) LIMIT 36 1967 5.71 7 1 20 1 3 39.61 67.18 N ( ) ( ) 3/ 569 5.38 7 18 3 1 9 7.0.74 -20.93 N (A) ( ) 38 1717 /.32 / 26 18 33 3.81 22.43 N ( ? ( ) 39 215? 7.34 7 30 21 7 18.10 61 .01 S (B) ( ) 40 221 3.72 8 11 23 39 33.31 -68.81 N (A) ( ) 41 243 6 .8/ 8 1 2 4 19 33.3.3 -67.13 N ( ) ( ) 42 390 5.36 8 13 6 19 19.15 -55.29 N { ) (S) 43 1993 6.81 8 25 17 51 39.46 25.28 N (S) ÍB) 44 2108 6.40 8 26 19 15 49.30 34.72 N (S) (B) 45 2220 /.00 8 ?/ 17 59 58.36 43.59 S (B) ( ) 46 2366 1.22 8 28 19 37 42.39 53.89 s ( ) ( ) 47 2373 6.22 8 28 20 6 7 26.54 54.18 s ( ) ( ) 48 994 6.49 9 13 3 49 22.68 -35.97 N ( ) < ) 49 2066 6.43 9 22 18 3 8.01 17.36 s (S) ( ) 30 2579 7.33 9 26 1? 57 57.14 46.22 s (S) ( ) 51 2605 /.14 9 26 23 9 50.67 4 7.35 s ( ) (A) 52 2756 7.44 9 27 23 9 19.86 57.05 s ( ) (A) 53 3017 3.33 9 29 22 23 4.14 73.76 s ( ) ( ) 44
YEAR 1990 MONTH 10-12 ( 5 4 - 6 7 )
SEQ NZC NO MAG MON DAY H M S SUNLIT(%) LIMIT 54 1099 6.02 10 11 3 0 2.73 -50.56 N (A) (B) 55 1242 6.83 10 12 5 8 46.33 -39.10 S ( ) (S) 56 3205 6.82 10 28 18 46 4.55 68.37 S ( ) ( ) 57 1187 7.12 11 8 0 58 15.14 -66.60 N (A) (B) 58 1439 5.87 11 10 4 20 58.48 -43.61 S ( ) (S) 59 1441 6.37 11 10 5 0 24.84 -43.34 S ( ) (S) 60 1649 6.26 11 12 5 53 54.63 -23.55 s ( ) (S) 61 1845 6.52 11 14 4 21 17.95 -9.48 s (A) (S) 62 2652 6.43 11 20 20 18 26.98 9.44 s ( ) ( ) 63 1611 5.66 12 9 3 30 12.81 -49.75 s C ) (S) 64 1717 7.32 12 10 4 14 33.21 -39.37 s ( ) ( ) 65 2269 5.44 12 15 5 3 13.33 -3.54 s (A) (S) 66 3131 5.54 12 21 19 52 47.99 17.56 s (S) ( ) 67 65 7.29 12 25 18 48 59.67 56.10 s (S) ( ) 45
TIME SYSTEMS
This section is intended to serve established amateurs and professional astronomers - i.e. those having some knowledge of time and coordinate systems. Space in this booklet does not permit full explanation, which in any case would appear complicated to the layman.
TIME SIGNALS FROM RADIO STATION ZUO Radio signals of mean solar time are generated by the Time Frequency Project in the Electro-magnetic Metrology Programme of the Division for Production Technology of the CSIR in Pretoria. They are broadcast by the Post Office, the 2.5 and 5 MHz signals from Olifantsfontein, and the 100 MHz signals from Johannesburg.
Carrier Frequency Radiated Power Time of Transmission 2,5 MHz 4 kW 2000 - 0600 SAST 5 MHz 4 kW Continuous
The signals consist of one pulse per second, each pulse consisting of 5 cycles of 1000 Hz tone. The first pulse in every minute is lengthened to 500 milliseconds. Morse code announcements are made during the minute preceding every fifth minute. They consist of the call sign ZUO (repeated 3 times) and the Universal Time (formerly known as Greennwich Mean Time) at the next minute. (A special coding indicating UT1 minus UTC is also indicated in the first 15 seconds of the minute by slightly lengthened second pulses).
SOUTH AFRICAN STANDARD TIME South African Standard Time (as in everyday use) is mean solar time on the 30° East meridian (which runs east of Johannesburg and just west of Durban) and is exactly 2 hours ahead of Universal Time.
TIME OF SUN'S TRANSIT OVER 30° MERIDIAN The table below gives the SAST when the Sun transists the 30* meridian - and a sundial on that meridian reads noon.
h m s h m s h a s Jan i 12 3 32 May ii 11 56 20 Sep 18 11 54 13 ii 12 7 54 21 11 56 31 28 11 50 44 21 12 11 17 31 11 57 36 Oct 8 11 47 37 31 12 13 27 Jun 10 11 59 21 18 11 45 13 Feb 10 12 14 15 20 12 1 28 28 11 43 50 20 12 13 45 30 12 3 35 Nov 7 11 43 41 Mar 2 12 12 12 Jul 10 12 5 18 17 11 44 56 12 12 9 49 20 12 6 19 27 11 47 34 22 12 6 57 30 12 6 26 Dec 7 11 51 2 3 Apr 1 12 3 56 Aug 9 12 5 31 17 11 56 1 11 12 1 5 19 12 3 39 27 12 0 30 21 11 58 43 29 12 1 00 31 12 2 55 May 1 11 57 6 Sep 8 11 57 45
CORRECTION FOR PLACES NOT ON THE 30° MERIDIAN Approximate longitude corrections from the 30 East Meridian are provided below. To find the time of Sun’s transit over the local meridian, apply the longitude corrections to the data in the t a b l e .
Bloemfontein +15™ East London + 8“ Port Elizabeth +18“
Bulawayo +6“ Grahamstown +14“ Pretoria +7“
Cape Town +46m Johannesburg +8™ Harare -4“
Durban -4“ Kimberley +21™ Windhoek +52m 46
SIDEREAL TIME ON THE 30* MERIDIAN
At At At At At At 0 hrs 21 hrs 0 hrs 21 hrs 0 hrs 21 hrs h m h m h m h m h m h m Jan 1 6 41 3 45 May 11 15 14 12 17 Sep 18 23 46 20 50 11 7 21 4 24 21 15 53 12 57 28 0 26 21 29 21 8 0 5 4 31 16 33 13 36 Oct 8 1 5 22 9 31 8 39 5 43 Jun 10 17 12 14 15 18 1 45 22 48 Feb 10 9 19 6 22 20 17 51 14 55 28 2 24 23 27 20 9 38 7 2 30 18 31 15 34 Nov 7 3 3 0 7 Mar 2 10 38 7 41 Jul 10 19 10 16 14 17 3 43 0 46 12 11 17 8 21 20 19 50 16 33 27 4 22 1 26 22 11 37 9 0 30 20 29 17 33 Dec 7 5 2 2 5 Apr 1 12 36 9 40 Aug 9 21 9 18 12 17 5 41 2 45 11 13 15 10 19 19 21 48 18 51 27 6 21 3 24 21 13 53 10 58 29 22 27 19 31 31 6 36 3 40 May 1 14 34 11 38 Sep 8 23 7 20 10
CORRECTION FOR PLACES NOT ION THE 30* MERIDIAN Approximate longitude corrections from the 30° Hast Meridian are provided bel< To find the sidereal times at SAST 0 hrs and SAST 21 hrs apply the following corrections to the data in the table
Bloemfontein -15ra East London -S'" Port Elizabeth -18“
Bulawayo -6* Grahamstown -14™ Pretoria -7“
Cape Town -46“ Johanne sburg -8“ Harare +4™
Durban +4'" Ki mberley -21“ Windhoek -57“
TELESCOPE SETTING When a telescope equipped with setting circles is aimed on the meridian, its R.A. circle should read the sidereal time. Thus one can calculate the sidereal time and then set the circle, but it is usually simpler to aim the telescope at one of the well known stars given below and then to adjust the R.A. circle.
A LIST OF BRIGHT STARS FOR CHECKING TELESCOPE CIRCLES (1990.3)
Star R.A. Dec . M a g . Sp Star R.A. D e c . Mag. Sp h m ° * h m ' AC HERNAR 1 37.4 -57 17 0.6 B5 PROCYON 7 38.8 5 15 0.3 F5 ALDEBARAN 4 35.4 16 30 1.1 K3 REGULUS 10 7.9 12 1 1.3 B8 RiCEL 5 14.1 -8 13 0.3 B8 SPICA 13 74.7 -11 7 1.2 B2 BETELCEUSE 5 54.6 7 24 0.4 MO ARCTURUS 14 15.3 19 14 0.2 K0 CANOPUS 6 73.7 -52 41 -0.9 F0 ANT.ARES 16 28.9 -26 25 1.2 Ml STRIUS 6 44.7 -16 4? -1.6 AO At.TAIR 19 .30.3 8 51 0.9 A> 47
ASSA OFFICE BEARERS
COUNCIL
President: Dr I. S . Class Hon. Treasurer: Mr D. Duprez Vice-Presidents: Mr J. P.G. Cramb Hon. Secretary: Mr H .E . Krumro Mr J. A. da S. Campos Business Manager: vacant Dr T. Lloyd Evans Membership Secretary: Mrs A. Joubert Members: Mr M. G. Soltynski Mr M. D. Overbeek Prof W. Vargau Mr B. D. Fraser
CAPE CENTRE PRETORIA CENTRE
Chai rm a n : Mr J. Davison Chairman: Prof W . Wargau Vice-Chairman: Mr J. Joubert Vice-Chairman: Dr J. Smit Secretary: Mr B. Skinner Hon. Secretary: Mr N. Young Treasurer: Mr C. D. Allen Hon. Treasurer: Mr M. Poll PRO: Mr E. v.d. Walle Librarian: Mi's E. Young Curator of Curator of Instruments: Mr F. Bryan Instruments: Mr F. le Roux Committee: Mr S. Kleyn Assistant Curator: Mr M. Geyser Mrs Ci. Momberg Urania Editor: Mr M. Haslarn Mr C. Turk C B C R e p . : Mrs P. South Mr P. van Heusden Council Rep.: Mr M. Hasiam Council Rep.: Mrs A.. Joubert Additonal Member: Mr P. I.ourens
BLOEMFONTEIN CENTRE HARARE CENTRE
Chairman: Chairman: Mr M. Begbie Vice-Chairman: Secretary: Mrs L. Murphee Secretary: Treasurer: Mr C . Bakker Committee: PRO: Mr D. Pringle-wood Commi ttee: Mr J . Vincent Mr N . MacDonald NATAL CENTRE Mrs E. Ell is-Whitfield
Chairman: Mr J. Campanini Vice-Chairman: Mr P, Cramb TRANSVAAL CENTRE Secretary: Mr R. Resnik Treasurer: Mr C. Beck Chairman: Mr N. Wakefield N'Daba Editor: Mrs 1.. Rens Vice-Chairman: Mr C. Winskill Librarian: Miss A. Banting Secretary: Mrs I. Randall Council Rep.: Mr J. Campanini Treasurer: Mrs R. Learmonth Curator of Canopus Editor: Mr D. West (ex officio) Instruments: Mr P. Cramb Librarian: Mr N. Wakefield PRO: Mrs P Ross Curator of Committee: Mr N. Cornelius Instruments: Mr D. Michie Council Rep.: Mr N. Wakefield NATAL MIDLANDS CENTRE Archi v i s t : Mr F. van Nieuwkerk Co-ordinator of Chairman: Dr G. Prosser Observations: Mr B. Fraser Secretary and A.S.T.S. Liason: Mr N. Wakefield Treasurer: Mr J. Watson Corami tt e e : Mr P. van Laun Librarian: Mrs S . Dale Mr J . Wooton Notice Paper: Mr R. Jarmain Mr C.J.M. Northam Special Interest: Mr R. Dale & Mr A. Scafturis Education: Mr C. Lake PRO: Mrs V Collingwood Council Rep.: Mr J. Watson 48 ASSA OFFICE B E A R E R S PAST PRESIDENTS 1922-23 S S Hougb 1945-46 R H Stoy 1968-69 J C Bennett 1923-24 R T A Innes 1946-47 W P Hirst 1969-70 J Churns 1924-25 J K E Haln 1947-48 J Jackson 1970-71 W c Bentley 1925-26 W Reid 1948-49 A E H Bleksley 1971-72 A H Jarrett 1926-27 H Spencer Jones 1949-50 W S Finsen 1972-73 K H Sterling 1927-28 A W Roberts 1950-51 H E Krun 1973-74 G A Harding 1928- 29 A W Iona 1951-52 A D Thackerav 1974- 75 C Papadopoulos 1929- 30 a E Mood 1952-53 J C Bentley 1975- 76 P A T Wild 1930-31 D Caneron-Swan 1953-54 D S Evans 1976-77 s S Booysen 1931-32 H L Alden 1954-55 P Kirchboff 1977-78 B Warner 1932-33 B Spencer Jones 1955-56 W H van den Bos 1978-79 R F Hurly 1933-34 D G Hclntyre 1956-57 S C Venter 1979-80 M Si Feast 1934-35 J K E Halu 1957-58 K W Feast 1980-81 M A Gray 1935-36 J Jackson 1958-59 H Haffner 1981-82 E E Baart 1936-37 H E Houghton 1959-60 P Saits 1982-83 J V Vincent 1937-38 J S Paraskevopoulos 1960-61 G G Cillie 1983-84 A P Fairall 1938-39 T Mackenzie 1961-62 H D Overbeek 1984-85 J S Bondietti 1939-40 R A Rossiter 1962-63 A J Wesselink 1985-86 G D Nicolson 1940-41 E B Ford 1963-64 A G F Norrisby 1986-87 C R G Turk 1941-42 H Knox Shaw 1964-65 H C Lagerveij 1987-88 J H Spencer Jones 1942-43 A F I Forbes 1965-66 A Henzies 1988-89 J P G Craib 1943-44 W H van den Bos 1966-67 G R Atkins 1944-45 A W J Cousins 1967-68 J Bers HONORARY SECRETARIES 1922 H W Schonegevel 1930-31 S Ske-.es 1965-80 T W Russo 1922-23 T Mackenzie 1931-34 H Horrocks 1981-82 Mrs M Fitzgereld 1923 C L O'Brien Dutten 1934-35 H W Schonegevel 1983- H E Kruaa 1923-30 B E Houghton 1935-65 A Henzies HONORARY TREASURERS 1922 J F Skjellerup 1937-40 Miss J R Robinson 1950-87 F H G Orpen 1922-23 A F I Forbes 1940-42 J B G Turner 1987-89 Mrs E C Olsen 1923-37 K H Sait!) 1942-50 H E Kruan 1989- D Duprez HONORARY MEMBERS Mr J C Bennet Dr G Heyian Mr M D Overbeek Hr W C Bentley Hr H C Krum Dr R B Stoy Dr A * J Cousins Hr C Papadopoulos Dr A J Wesselink Dr D S Evans Dr J H Oort Prof Ch Fehrenbach Mr F M G Orpen GILL MEDALLISTS 1956 H Knox Shav 1965 R H Stoy 1983 M W Feast 1957 Si P Hirst 1967 W S Finsen 1984 M D Overbeek 1958 J Jackson 1970 J C Bennett 1988 D S Evans 1960 Si H van den Bos 1976 A D Thackeray 1963 A Si J Cousins 1981 C Papadopoulos MCINTYRE AWARDS 1971 D S Evans, T J Deeaing, Mrs B K Evans í S Goldfarb 1983 B Warner LONG SEBVICE AWARDS 1984 J Churas 1988 R F Hurly 49
JULIAN DATE AT 1400 BOUES - SAST 1990 JAX. FEB. KAE. APS. XAÏ JUK. JUL. AUG. SEP. OCT. HOV. DEC. 2447 2447 2447 244 2448 2448 2448 2448 2448 2448 2448 2448 1 893 924 952 7983 013 044 074 105 136 166 197 227 2 894 925 953 7984 014 045 075 106 137 167 198 228 3 895 926 954 7985 015 046 076 107 138 168 199 229 4 896 927 955 7986 016 047 077 108 139 169 200 230 5 897 928 956 7987 017 048 078 109 140 170 201 231 6 898 929 957 7988 018 049 079 110 141 171 202 232 7 899 930 958 7989 019 050 080 111 142 172 203 233 8 900 931 959 7990 020 051 081 112 143 173 204 234 9 901 932 960 7991 021 052 082 113 144 174 205 235 10 902 933 961 7992 022 053 083 114 145 175 206 236 11 903 934 962 7993 023 054 084 115 146 176 207 237 12 904 935 963 7994 024 055 085 116 147 177 208 238 13 905 936 964 7995 025 056 086 117 148 178 209 239 14 906 937 965 7996 026 057 087 118 149 179 210 240 15 907 938 966 7997 027 058 088 119 150 180 211 241 16 908 939 967 7998 028 059 089 120 151 181 212 242 17 909 940 968 7999 029 060 090 121 152 182 213 243 18 910 941 969 8000 030 061 091 122 153 183 214 244 19 911 942 970 8001 031 062 092 123 154 184 215 245 20 912 943 971 8002 032 063 093 124 155 185 216 246 21 913 944 972 8003 033 064 094 125 156 186 217 247 22 914 945 973 8004 034 065 095 126 157 187 218 248 23 915 946 974 8005 035 066 096 127 158 188 219 249 24 916 947 975 8006 036 067 097 128 159 189 220 250 25 917 948 976 8007 037 068 098 129 160 190 221 251 26 918 949 977 8008 038 069 099 130 161 191 222 252 27 919 950 978 8009 039 070 100 131 162 192 223 253 28 920 951 979 8010 040 071 101 132 163 193 224 254 29 921 980 8011 041 072 102 133 164 194 225 255 30 922 981 8012 042 073 103 134 165 195 226 256 31 923 982 043 104 135 196 257
JANUAEY FEBSDASY NAECH APEIL Su Ko Tvi He Th Pr Sa Su Xo Tu He Th Ft Sa Su Xo Tu He Th Fr Sa Su Xo Tu He Th Fr Sa 1 2 3 4 5 6 1 2 3 1 2 3 1 2 3 4 5 6 7 7 8 9 10 11 12 13 4 5 6 7 8 9 10 4 5 6 7 8 9 10 8 9 10 11 12 13 14 14 15 16 17 18 19 20 11 12 13 14 15 16 17 11 12 13 14 15 16 17 15 16 17 18 19 20 21 21 22 23 24 25 26 27 18 19 20 21 22 23 24 18 19 20 21 22 23 24 22 23 24 25 26 27 28 28 29 30 31 25 26 27 28 25 26 27 28 29 30 31 29 30
HAY JUNE JULY AUGUST Su Xo Tu Me Th Pr Sa Su Ho Tu He Th Fr Sa Su Xo Tu He Th Fr Sa Su Xo Tu He Th Fr Sa 1 2 3 4 5 1 2 1 2 3 4 5 6 7 1 2 3 4 6 7 8 9 10 11 12 3 4 5 6 7 8 9 8 9 10 11 12 13 14 5 6 7 8 9 10 11 13 14 15 16 17 18 19 10 11 12 13 14 15 16 15 16 17 18 19 20 21 12 13 14 15 16 17 18 20 21 22 23 24 25 26 17 18 19 20 21 22 23 22 23 24 25 26 27 28 19 20 21 22 23 24 25 27 28 29 30 31 24 25 26 27 28 29 30 29 30 31 26 27 28 29 30 31
SEPTEXBEE OCTOBEE HOVEXBEE DECEXBEE Su Xo Tu He Th Fr Sa Su Xo Tu He Th Fr Sa Su Xo Tu He Th Fr Sa Su Xo Tu He Th Fr Sa 1 1 2 3 4 5 6 1 2 3 1 2 3 4 5 6 7 8 7 8 9 10 11 12 13 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 16 17 18 19 20 11 12 13 14 15 16 17 9 10 11 12 13 14 15 16 17 18 19 20 21 22 21 22 23 24 25 26 27 18 19 20 21 22 23 24 16 17 18 19 20 21 22 23 24 25 26 27 28 29 28 29 30 31 25 26 27 28 29 30 23 24 25 26 27 28 29 30 30 31 50
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