With the summer monsoon having taken hold in the southern USA, stopping the big surveys from operating for most of the month, time was spent catching some NEOs at their second and subsequent oppositions.
Working with Roger Dymock we also went after some more normal main belt minor planets on the FUAP (Follow Up Astrometric Program) target list at http://asteroidi.uai.it/ which is maintained by Sergio Foglia on behalf of the UAI Minor Planets Section. This site lists minor planets of mag +18.5 or brighter that are in need of observation, whether newly discovered and under-observed, or awaiting recovery at their second or subsequent oppositions.
The last week of the month saw a flurry of NEO discoveries from the surveys in a brief respite from their bad weather, with several objects at mag 16-17.
Tuesday, 1 August 2006
Wednesday, 28 June 2006
2006 June notes: 2006 KZ112 and 2006 MU6
Several objects were followed over a period of a couple of weeks during the month, including 2006 KZ112 which has an interesting 'Encke like' orbit (2006 KZ112: q=0.29, e=0.89, i=38, P=4.0, Encke: q=0.33, e=0.85, i=12, P=3.3).
Of the other objects observed, 2006 MU6 was picked up on June 27 after being discovered by Spacewatch on June 20th and is a possible Mars Trojan (though the uncertainties on the orbital elements are still large). Already very faint it is predicted to fade quickly.
Of the other objects observed, 2006 MU6 was picked up on June 27 after being discovered by Spacewatch on June 20th and is a possible Mars Trojan (though the uncertainties on the orbital elements are still large). Already very faint it is predicted to fade quickly.
Saturday, 3 June 2006
2006 May notes: 2006 JE, 2006 GY2, 2006 HX57, 2006 JV26 and 2006 JF42
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.
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.
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!
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