Ordinary Meeting, 2006 December 16


The December Sky

Dr Miles opened with an update on Nova Cygni 2006 (aka. V2362 Cygni), which had flared in early April. At the last meeting, an anomalous brightening had been reported; Dr Arne Henden, Director of the AAVSO, had then predicted that the light-curve would plateau for a time, but fade within 2-3 weeks. Observations by a number of BAA members had since confirmed this prediction.

The speaker turned to report that Peter Birtwhistle, an active near-Earth asteroid observer, had discovered four new main-belt asteroids within the past month. This brought the total number of his discoveries to 62.

Turning to meteor showers, Dr Miles reported that the Ursid maximum would be on December 22. Though this shower normally yielded rates of only around 10 ZHR, Esko Lyytinen and Markku Nissinen had published predictions of an enhanced rate of up to 35 ZHR this year, resulting from the Earth's orbit intersecting a stream of dust laid down by the shower's parent, Comet 8P/Tuttle, 75 orbits ago, in AD 996. The enhanced rate would likely peak at around 19h27 UT, though it might extend from 18h10 to 20h50 UT. The speaker noted that the observing conditions were forecast to be good: the evening of maximum would be Moon-free this year, and the radiant of this shower was at high altitude in the UK sky.

Dr Miles closed by mentioning an exciting comet prospect for early January: 2006 P1 (McNaught), discovered in August. Currently at around mag 5 and 14° from the Sun, it would reach perihelion on January 12, passing within Mercury's orbit and skimming a mere 0.17 AU from the Sun. On the evenings of January 7-9 it would be briefly visible in evening twilight shortly after sunset at around 5pm, positioned vertically above the azimuth where the sun had set, at a similar altitude to Venus, which lay 20° away in azimuth. Given its close approach to the Sun, this could be a spectacular object despite the necessity of twilight observing.

After January 9, the nucleus itself would be too close to the Sun for observation, though it would appear within the field of the LASCO camera on the SOHO satellite. If it grew a substantial tail, however, this might be visible stretching above the western horizon after sunset.

The President then welcomed Dr Stewart Moore, Director of the Deep Sky Section, to present the meeting's final talk.




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