Orwell Astronomical Society (Ipswich)
Planets, 16 February - 28 December 1983
Venus, 16 February - 28 December 1983
Sketches using a 60 mm refractor. Magnification generally 150x.
- 17:53-18:20 UT, 16 February 1983. Conditions good but hazy.
- 17:58-18:12 UT, 18 February 1983. Conditions very good. Used yellow filter. Observed two misty patches on the planet.
- 18:12-18:28 UT, 21 February 1983. Conditions good. Observed one large misty patch and a smaller area of shading on the planet.
- 17:56-18:08 UT, 22 February 1983. Conditions good but wind causing telescope shake. Used light green filter. Observed two misty patches.
- 17:40-17:52 UT, 23 February 1983. Conditions very good. Used light green filter. Observed three misty patches.
- 17:50-18:00 UT, 04 March 1983. Conditions very good. Used green and purple filters. Observed one misty patch near the north pole.
- 19:40-19:46 UT, 28 March 1983. Conditions bad with only fleeting clear glimpses of one faint marking towards the northern polar region. Used light-green filter.
- 19:46-19:56 UT, 03 April 1983. Conditions extremely good. Observed very delicate shadings on the cloud layers. Used yellow, green and purple filters. Best filter was purple one, which showed clearly all the detail reproduced in the sketch.
- 19:32-19:40 UT, 08 April 1983. Conditions extremely good. Definite dark shaded areas visible in the cloud structure. Used light-green filter.
- 19:00-19:22 UT, 09 April 1983. Conditions good. High activity on Venus; however all markings rather faint due to twilight sky. Sketch exaggerates visibility of feature: all are ill-defined contrast features. No filters used.
- 19:48-20:12 UT, 03 May 1983. Conditions initially extremely good showing large amounts of detail, but turned hazy towards the end of the observations. Observed two polar cusp caps, the northern one being very prominent, with a dark line under it. The southern cusp cap (feature labelled 3) was very small and I found it difficult to identify its shape. Position marked 1 showed an extremely white area in the cloud cover: was very prominent and appeared to be the brightest area on the planetary disk. Position marked 2 showed a long curved, bright area. In addition to areas 1 and 2, there were several dark areas visible without straining to see them. Used light-green filter.
- 19:40-20:24 UT, 08 May 1983. Conditions good but misty. An interesting observation showing two cusp caps: the southern cap appeared a lot larger than when last observed on 03 May. The cusp caps have a tendency to be harder to recognise with a light green filter as the sky darkens; they are best observed using a yellow filter in twilight conditions or broad daylight. The feature labelled 3 retained its brilliant white colour but was perhaps a little darker than when observed on 03 May. Feature 4 appeared as a very dark curved line around the perimeter of the southern cusp cap: it was easily the darkest feature visible. Used yellow and light-green filters.
- 17 June 1983, the time of predicted dichotomy. Note that the drawing shows the apparent phase as significantly in excess of 50%.
- 22 June 1983. On this date, the apparent phase reached 50%. The difference between predicted and observed times of dichotomy is known as the Schröter effect.
- 19:40-22:00 UT, 04 July 1983. Conditions very good. Features 2 and 3 are cusp caps. The southern cusp cap was very prominent. Used light-green filter.
- 20:08-20:16 UT, 07 July 1983. Conditions extremely good. Southern cusp cap very prominent. Features marked 4 and 5 are the southern and northern cusp caps respectively. No filters used.
- 19:52-20:08 UT, 23 July 1983. Conditions good. Used light-green filter.
- 07:04-07:12 UT, 06 December 1983. The southern cusp cap is very prominent and easily recognisable. Used yellow filter.
- 07:58-08:06 UT, 28 December 1983. Conditions: very steady atmosphere. The terminator of the southern cusp cap is very prominent and dark, even when not using a yellow filter.
Figure 1, a-f.
Figure 2, a-d.
Figure 3, a-b.
Figure 4, a-b.
Figure 5, a-b.
Figure 6, a.
Figure 7, a-b.
Jupiter & Saturn, 11 June - 20 August 1983
Sketches using a 60 mm refractor and the Orwell Park 26 cm refractor.
- Figure 8. Jupiter, 11 June 1983, 20:36-21:06 UT. Telescope: 60 mm refractor. Sky conditions: very good twilight sky. Considerable activity visible in the equatorial belts. "a" marks a white spot in the northern equatorial belt and "b" marks a white spot with a darker area near it.
- Figure 9. Saturn, 11 August 1983, 22:12-22:20 UT. Telescope: Orwell Park 26 cm refractor. Sky conditions: excellent. No moons were observed, but three very prominent belts were visible on the planet. The middle belt is thought to be the shadow of the rings on the cloud tops.
- Figure 10. Jupiter, 20 August 1983, 19:36-19:46 UT. Telescope: Orwell Park 26 cm refractor. Sky conditions: generally good but blurring at regular intervals. Interesting features visible between the two equatorial belts, which were considerably fainter than the sketch below suggests.
- Figure 11. While producing the sketch of figure 10, I could observe two of Jupiter's Galilean satellites, Ganymede and Europa, in the field of view. The figure indicates their position in relation to the planet. Callisto was outside the field. I did not discern Io, in transit against the disk of the planet.