Saturday 3 December 2005

2005 November notes: 2005 WC, 2005 VX3, 2005 WY3, 2005 WN3, 2005 WY, GS5BRH

November was an exceptional month for me, not so much the 16 usable nights, but the CCD shutter was open for 74 hours in total. A number of objects turned out to be interesting:

2005 WC was confirmed here after it was posted on the NEOCP following discovery by LINEAR, moving at 75"/min. Richard Miles also managed to get some positions of it that night as it headed quickly towards the north horizon. Richard's and my positions were the only follow-up reported in the world before it went out of view less than 24 hours later.

2005 VX3 was a very faint object observed while on the NEOCP and was finally announced as having a period of 32 years based on observations from Nov 1-6th. Subsequent observations from Great Shefford on Nov 13 and 21 showed it to have a very much longer period, possibly even being in a hyperbolic orbit.

2005 WY3 was another very faint and slow moving object observed while on the NEOCP and it ended up being determined to be about 6AU from the Earth. With a period of 19 years, q=1.8 and reaching perihelion in about 3 years it will be interesting to keep an eye on this one.

An object discovered by the Mt Lemmon Survey on Nov 25 and rapidly approaching Earth was (just!) caught on the edge of 5 consecutive frames, moving at 175"/min. This was enough to confirm the object and it then received the designation 2005 WN3. It turned out to be just inside the Moons orbit when I imaged it and passed just 6.5 Earth diameters away less than 5 hours later, less than a month after catching 2005 UW5 inside the Moon's orbit.

While imaging fast moving NEO 2005 WY on the morning of Nov 27, another even faster moving object was recorded speeding through at 294"/min, staying in the field of view for 3m 46s on 35 separate frames, but unfortunately I didn't spot it on the images until the next evening, by which time it was hopelessly lost. After positions were measured, assuming it might be an artificial satellite I tried fitting a geocentric orbit to the positions but none of the solutions were tenable (with perigee always smaller than the Earths radius). I gave it temporary name GS5BRH and sent the positions to the Minor Planet Center and heard back that they couldn't match to any known satellite and that although some of the residuals were up to 6" or even 8", it may have been about 0.002 AU from Earth at the time.

Wednesday 9 November 2005

2005 October notes: 2005 UH5, 2005 UW5, 2004 FH

There were several highlights this October, I managed to catch 2005 UH5, the NEO that Roger Dymock found in the online FMO project images on 27 Oct. It was quite a difficult object through high cloud, I searched for it over multiple fields on the night but didn't identify it until the next day. Congratulations to Roger!

Then on 29th Oct I managed to follow 2005 UW5 while it was inside the orbit of the Moon, which is a first for me. I first picked it up through gaps in clouds at 18:46 UT when it was moving at 330"/min and when last seen at 21:19 UT it had accelerated to 525"/minute. At that time it was only 17 Earth diameters away!

An 11 frame animation of 30 seconds of motion between 21:12:00 -21:12:30 UT on 29th October. Each frame is a 1 second exposure and the animation plays back in real time, exactly as the images were taken, with a 2 second gap between frames. The field of view is 18.3'x18.3'
Of the NEOs with reliable orbits that are known to have had close approaches to the Earth, this approach was the 16th closest ever, but in fact only one of the other 15 (2004 FH) was actually observed while it was closer to the Earth than 2005 UW5 was on 29th October.