2006 January notes: 2006 BA, 2006 BV39, 2006 BF56, 2006 BH99

The first half of January was very poor with just 3 usable nights, but the second half was better with 10 nights and brought some interesting fast movers...

On Jan 20/21st 2006 BA was observed at mag +16.5, passing by at 2 lunar distances (l.d.) and moving at 60"/min.

Then on Jan 26th the Spacewatch 1.8-m reflector discovered 2006 BV39, confirmed 15 hours later from Klet in the Czech Republic. It was about 4 l.d. at discovery and closing fast. In conversation with Monty Robson at 932 (John J. McCarthy Observatory in Connecticut) on the morning of the 27th I mentioned that 2006 BV39 would be an interesting target the next night. Nowhere had reported it to the Minor Planet Center after Klet's confirmation when I tried but failed to find it at midnight on the 28th. On checking with Monty, he mentioned that he had got it the night before but had not reduced the astrometry. He kindly measured the positions immediately and sent them through to me, allowing me to update the ephemeris and then to locate the NEO. It was 23' W of the MPC's prediction and would have been very difficult to find without the correction. By this time it was moving at 210"/min and was just 5,000 miles outside the Moon's orbit. I followed it until 05:14UT on the 29th by which time it had accelerated to 277"/min and had crossed 28,000 miles inside the Moon's orbit with closest approach about 2 hours later at 0.9 l.d. This was the third NEO I have tracked while inside the Moon's orbit in four months!

Just a few hours later news came through of a mag +21 NEO discovered from Mt. Lemmon with the 1.5-m reflector at 7:22UT and followed by them for 5 hours, during which time the apparent speed went from 10"/min to 14"/min. Obviously approaching fast, it was confirmed almost simultaneously from Klet and Great Shefford at about 22:10UT that night and given the designation 2006 BF56 by the Minor Planet Center. By then it was mag +19.5, moving at 48"/min and was about 3 l.d. away. It was followed from Great Shefford until 06:42UT when it was lost in morning twilight, by which time it was about mag +17.5, had accelerated up to 346"/min and was only 23,000 miles outside the Moon's orbit. It crossed inside the Moon's orbit just 15 minutes later and closest approach was at 10:32UT when it passed at 0.5 l.d. Although not reported after 06:42UT it was anyway unobservable by 12:00UT on 29th, having faded back to mag +21 again but also moving at 1,000"/min! The entire apparition was over in less than 1.5 days during which time it had covered nearly 180 degrees of sky.

Although badly hampered by cloud, 2006 BH99 was then observed on the night of Jan 30 at mag +17 at 2.7 l.d., moving at 90"/min, passing by at just 1.2 l.d. about 14 hours later. Quite a busy few days!

2005 December notes: 2005 YQ96, 2005 YW

There were not many long observing runs on NEOs during December, but probably the most interesting result was helping confirm the discovery of 2005 YQ96 on December 30th, which with an aphelion distance of 0.992 AU makes it the 6th known "Apohele", or Minor Planet with it's orbit completely inside the Earth's orbit.

Also, 2005 YW discovered on December 21 was examined carefully on a couple of nights for signs of cometary activity but it appeared stellar in a 26 minute exposure in good conditions on the 28th. This object has a period of about 2000 years and with perihelion at 2.0 AU due next winter it is possible it may eventually show activity. Unfortunately it will be lost in twilight this coming spring and will pull away from the Sun next winter but at far southerly declinations, not visible from the UK.

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.

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.