Orwell Astronomical Society (Ipswich)

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Mars At Opposition, 01 October - 16 November 1988

Mars, the so called Red Planet, was at opposition on 28 September 1988 and has not been better placed for observations from the northern hemisphere since 1725. The planet attained magnitude -2.8, just brighter than Jupiter, and an angular diameter of 23.8". The opposition occurred when Mars was close to perihelion, and the angular diameter was very close to the largest value possible. The apparition was special because the large angular diameter was combined with a relatively high altitude (Mars was close to the celestial equator at opposition). This meant much better seeing than usually occurs with perihelic oppositions when Mars is generally well south of the celestial equator. Because of the special nature of the apparition, the British Astronomical Association (BAA), the Planetary Society, the Association of Lunar and Planetary Observers (ALPO), the Oriental Astronomical Association (OAA) and the NASA Jet Propulsion Laboratory (JPL) sponsored an International Mars Patrol (IMP). The IMP strongly recommended the use of a standard disk of 42 mm diameter for recording observations of Mars. OASI encouraged members to make observations of Mars during the apparition and to submit results on the standard disks.

The close opposition meant that even relatively small telescopes were capable of revealing the major features on the surface of Mars, particularly the polar caps and the dusky area Syrtis Major. However, in practice a 150 mm reflector was the smallest instrument necessary to observe fine detail and ideally an aperture of at least 250 mm was needed to do serious work. The 26 cm refractor at Orwell Park is capable of resolving fine detail under ideal conditions. Following opposition, as the nights darkened, I made some observations of Mars using my 25 cm Newtonian reflector at home and the 26 cm refractor at Orwell Park.

19881001_Mars_DBP.bmp 01 October 1988

19881005_Mars_DBP.bmp 05 October 1988

19881023_Mars_DBP.bmp 23 October 1988

19881027_Mars_DBP.bmp 27 October 1988

19881031_Mars_DBP.bmp 31 October 1988

19881102_Mars_DBP.bmp 02 November 1988

19881104_Mars_DBP.bmp 04 November 1988

19881113_Mars_DBP.bmp 13 November 1988

19881116_Mars_DBP.bmp 16 November 1988

David Payne