Sunday, 8 March 2009

2009 February notes: 2009 BL58, 2009 BG81, 2009 DS43

Early in February a few fast movers were observed, Apollo 2009 BL58 had been discovered at the end of January by the Catalina Sky Survey. When first observed on 9th Feb it was mag +17.1 and placed 5° SE of Regulus, moving swiftly SE. It was observed two nights later, 45° further on in Hydra at -25° Dec, a degree S of Alpha Corvus and although still mag +17.7, because of its altitude of only 13° was much more difficult to record. It was just a few hours away from its closest to Earth at 4.8 Lunar Distances (LD) and moving at 70"/min.

Apollo 2009 BG81 was a LINEAR discovery from Jan 31st and picked up on the evening of Feb 1st moving at 51"/min, already as close as 4.6 LD but only 19th mag. It came to 4.4 LD on Feb 2nd and was observed by three other observatories but was not reported after that date. With an estimated diameter of 7 metres 2009 BG81 was intrinsically about 4 times smaller than 2009 BL58.

At the end of the month another small Apollo, 2009 DS43 was picked up on 27th Feb in Sextans, first by LINEAR and 97 minutes later by the Catalina Sky Survey (CSS). CSS reported their observations first and were credited with the discovery. It was mag 18 and moving almost due N at 38"/min. I first observed it on the evening of 28th Feb at mag +17.8 by which time it had accelerated to 94"/min and had reached +39° Dec. By then it was at 6.9 LD and would reach its closest at 3am on 1st March at 6.7 LD. By the evening of the 1st it was at a declination of +76° midway between the Pointers and Polaris, had slowed to 81"/min and receded to 7.4 LD and was fading fast, more than 1 mag fainter than the previous night. The Minor Planet Center didn't receive any further reports of it.