Ordinary Meeting and Exhibition Meeting, 2002 September 21

 

The September Sky

Mr Mobberley opened with the comet scene, displaying a light curve for Ikeya-Zhang from his May talk, commenting on changes to the magnitude estimates. After peaking in March, Ikeya-Zhang had continued to produce a number of surprises, including an anti-tail as it faded towards mag 9-10. The speaker illustrated this anti-tail with a number of images from June.

There were at least seven comets brighter than mag 14, and hence imagable by many amateurs. The speaker displayed a number of images by Michael Jäger from Austria, commenting that his images were of superb quality and prolific quantity, despite continuing to use film photography as opposed to digital equipment. 7P/Pons-Winnecke and 46/P Wirtanen continued to give a good show, and Mr Mobberley reported that the discovery of 2002O4 (Hoenig) had been the first from German soil since 1946, appearing to be a genuine miss by LINEAR. This comet would be too low for evening observation by late October, but would become a morning comet. Comet 2002O6 (SWAN) was currently at mag 6 and a good candidate for visual observation. This comet had been discovered by Suzuki from real-time data from the SOHO satellite observatory, but curiously named after the Solar Wind Anisotropy (SWAN) probe rather than the usual SOHO labelling.

Asteroid 2002NY40 caused a media stir when it passed within 106km of the Earth on August 18. It was the first 500-1000m class object to have passed this close since 1937. A number of images of the pass were shown, including one by Nick James, which had been taken through cloud from Chelmsford. Michael Jäger had produced an excellent image of the asteroid passing by NGC6863. Radar imagery of the object had been attempted, though little interesting surface feature had been revealed.

The hypernova in M74 had peaked in March at mag 12, and faded to mag 14 by the end of the month. It had not faded as rapidly as expected, and remained at mag 17 at the time of the meeting. Mark Armstrong had made several recent supernova discoveries, including 2002em, which was mag 18 at discovery, and most notably 2002ct, which at mag 20.1 was the faintest supernova ever discovered by an amateur. Tom Boles had discovered 2002eh at mag 16.

Moving onto planetary observation, Mr Mobberley opened with images of Uranus' moons by Ed Grafton. The speaker believed these to be the first amateur images he had seen resolving surface features on these moons. A composite image of Saturn had also been taken by Ed Grafton on September 17, achieving superb clarity using ten images with each of red, green and blue filters in turn. Saturn would be rising in the UK sky in the coming months, and with the rings at 63° they were near their highest possible tilt. Jupiter would also be rising towards the end of the year, and with Damian Peach now resident in Tenerife, impressive images were anticipated.

Mr Mobberley recommended the occultation of a mag 9 star, TYC 1402-01027-1, by Jupiter at 6am on 2002 November 16. The penumbral lunar eclipse of November 20 was not expected to be particularly spectacular, although on this occasion the Moon would pass close to the umbra, improving prospects. The speaker displayed a number of superb solar images by Ray Emery, which had revealed an impressive amount of detail in sunspots and flares. These had been recorded using a small aperture Chinese refractor and ccd.

A number of observers would be travelling to view the total solar eclipse of December 4, which would be visible across southern Africa, albeit very low in the sky. There would be very long shadows cast in one direction. To close, the speaker demonstrated a piece of eclipse simulation software by Association member Andrew Sinclair, which was available on the web.

Following the applause for Mr. Mobberley's lively and informative summary, the President welcomed Dr Richard McKim to review the work of the Mars Section.

Ashburn

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39.04°N
77.49°W
EDT

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