May was on the way to being my worst month since Nov 2003 until the unsettled spell finally ended on 27 May and four of the last five nights were clear.
The month had started well with some fast movers - 2006 JE was a LINEAR discovery that I managed to confirm when it was on the NEOCP, about 1/2 degree off track and moving at 94"/min. A much easier target because it was over 4 mags brighter at +14.0 but travelling at about the same speed was 2006 GY2 on May 15.9, just a few hours before it passed 7 lunar distances from Earth and the same time as it was being observed from Arecibo and Goldstone and found to be a binary with components of 400 m and 80 m diameter. 2006 HX57 was observed on May 6.0 at mag 16.5, moving at 92"/min and also 2006 JV26 on May 8.9 at mag 16.5 and moving at 290"/min, less than 3 lunar distances away.
An interesting object discovered on May 11 by the Catalina Sky Survey was 2006 JF42, observed from May 15-31, deep in the glow of evening twilight. It has a very short period of only 201 days (shorter than Venus) but with an eccentric orbit taking it from 0.28 AU at perihelion to 1.06 AU at aphelion, with the most favourable viewing circumstances being when aphelion occurs around May 21, when it would be placed in the opposition region of the sky south of the ecliptic. This year aphelion was only two weeks later but the best elongation achieved was only 96 degrees.
Saturday, 3 June 2006
Friday, 5 May 2006
2006 April notes: Integral, 2006 GA, 2006 GC, Comet 73P/Schwassmann-Wachmann
April was a much better month than the last few, with 19 usable nights.
The artificial satellite Integral wandered into the field of component 73P-N/Schwassmann-Wachmann on the morning of April 12th, moving at about 230"/min. Not knowing whether it was a close approaching NEO or a very unusual artificial satellite I followed it for 50 minutes until it ran into bright twilight, which was long enough to work out an orbit for it and to pick it up again 2 nights later. Thanks go to Tony Beresford and Mike McCants for identifying it for me.
A couple of NEOs were followed for several weeks (2006 GA & 2006 GC) but most were observed for much shorter arcs. A fair proportion of the early mornings during the month were spent imaging over 30 of the components of 73P as it approached the Earth.
The artificial satellite Integral wandered into the field of component 73P-N/Schwassmann-Wachmann on the morning of April 12th, moving at about 230"/min. Not knowing whether it was a close approaching NEO or a very unusual artificial satellite I followed it for 50 minutes until it ran into bright twilight, which was long enough to work out an orbit for it and to pick it up again 2 nights later. Thanks go to Tony Beresford and Mike McCants for identifying it for me.
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| Artificial Satellite Integral passes through the field of view of faint fragments of comet 73P/Schwassmann-Wachmann |
A couple of NEOs were followed for several weeks (2006 GA & 2006 GC) but most were observed for much shorter arcs. A fair proportion of the early mornings during the month were spent imaging over 30 of the components of 73P as it approached the Earth.
Saturday, 4 February 2006
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!
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!
Monday, 2 January 2006
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.
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.
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.
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.
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