The amount of activity on the Minor Planet Center's NEO Confirmation Page (NEOCP) was as expected, quite low during August, with the telescopes of the Catalina Sky Survey being out of action during the monsoon season in the South-West USA. However, LINEAR picked up a number of new objects, as did the WISE Infrared satellite above the atmosphere.
A LINEAR discovery designated 2010 PJ9 passed by at just under 3 Lunar Distances (LD) late on August 9th but weather only permitted catching it from Great Shefford on the morning of the 8th when it was at 6 LD and 16th mag, moving at 30"/min.
2010 PR66 was another LINEAR discovery made on August 15th and confirmed from Great Shefford later the same day. It was about 18th mag at that time but had reached 14th mag 3 weeks before discovery as it made a 10 LD approach in the evening sky that had gone completely unobserved. LINEAR's discovery was impressive, deep in the rich star fields midway between Sagitta and Delphinus, their search algorithms must be very good. Finding moving objects in rich star fields is something that LINEAR still seems to do better than the other surveys. For me, even knowing where to look, it took some time and many exposures to pick it out from the background stars, just to get a few position measurements.
Another stellar occultation was recorded, this time by (105) Artemis on the evening of August 18th (see details including the drift-scan image here). I recorded an 8 second event and Roger Stapleton in St. Andrews also recorded a positive event. The timings from these, together with three other observers in Europe allowed the 123 x 87km oval shape of the asteroid to be mapped out and the result can be seen on the European Asteroidal Occultation Results page for 2010. Click on the chords link to see the result and the link to the observers list showing all those contributing measurements to the the diagram.
I took some images of (105) Artemis before the occultation and measured astrometry from them, sending the positions of (105) Artemis to the Minor Planet Center. It was only later that I recalled that Artemis had been a target of mine 33 years earlier, from my previous location of Cheam (station 499) where I had submitted a single position from 1977 May 22, taken with a 300mm focal length telephoto lens with a 2x converter on Tri-X film, reduced by hand with the SAO Star Catalogue. That result still sits in the Minor Planet Center database and is now joined by my three (new technology) positions from 18 August 2010!
During a quiet NEOCP period towards the end of the month I set about trying to recover some NEOs that had only been seen at one opposition and were predicted to be having reasonably favourable apparitions now. I managed to locate four objects (2006 FE, 2007 VC138, 2008 TC4 and 2009 PY) on the night of August 30th and the weather held up enough for me to get confirming positions the next evening. I was very lucky with 2006 FE to pick it up by chance in a very rich star field in northwest Aquila in the first set of exposures taken, travelling across a little 1 arcmin void amongst the milky way background. The most challenging recovery though was 2009 PY, 20th magnitude and half a degree from prediction, requiring a number of my 18'x18' fields of view to be searched before finding the tell-tale motion of the faint NEO.
Showing posts with label occultation. Show all posts
Showing posts with label occultation. Show all posts
Friday, 10 September 2010
Tuesday, 8 June 2010
2010 May notes: MACE 2010, (130) Elektra occultation and 2010 KQ
After a four year gap since the last "Meeting on Asteroids and Comets in Europe" (MACE) in Vienna in 2006, the 5th MACE took place in Visnjan/Tican, Croatia during 21-23 May (http://www.minorplanets.org/MACE2010/). Richard Miles and I attended from the UK and in all about 50 amateur and professional astronomers from all over Europe attended, together with Steve Chesley/JPL from the USA. Richard and I had the pleasure of meeting Jan Vales (P/2010 H2), discussing at length with him and others Richard's ideas on possible mechanisms that may have caused the dramatic outburst that led to Jan's discovery. The meeting also boasted comet discoverers Michel Ory (P/2008 Q2) and Eric Elst (133P/Elst-Pizarro), Korado Korlevic (183P/Korlevic-Juric and 203P/Korlevic) and of course the meeting organizer Reiner Stoss, co-founder of the La Sagra Sky Survey team that is credited with comets P/2009 QG31, P/2009 T2 and P/2009 WJ50.
Following on from the (130) Elektra result (TA 551,299), another occultation was successfully captured from Great Shefford, this time of the mag +10.5 star TYC 5573-00543-1 by (80) Sappho on June 4. The drift-scan image shows the starlight being blocked out by the minor planet for 5.5 seconds and revealing the minor planet shining faintly at mag. +11.8. John Broughton's SCANALYZER software was used to reduce the time of disappearance and reappearance (see full details here). At least one other UK observer, Tim Haymes in Maidenhead, Berkshire is also known to have succeeded in obtaining a positive result and other results are expected from France and Italy, which may lead to a determination of the asteroid's shape when all the results are in.
As well as a few very close approaches by newly discovered minor planets (the closest being 2010 JV39 to 0.65 Lunar Distances (LD) on May 26 and 2010 JL88 to 1 LD on May 17) there was also the discovery of unusual object 2010 KQ, originally added to the Minor Planet Center's NEO Confirmation page (NEOCP) on May 16 and observed from Great Shefford on the evening of May 17. Soon after my positions were sent in to the Minor Planet Center, Associate Director Gareth Williams removed it from the NEOCP with a note "was not a minor planet", adding it instead to his "Distant Artificial Satellites Observation Page" at http://www.minorplanetcenter.org/iau/SpaceJunk/SpaceJunk.html and indicated to me that further observations would still be useful. I got another set of measures the next night and sent them in to the MPC as Artificial Satellite positions. The next day all the positions obtained from discovery to May 18 were published in MPEC 2010-K15, announcing the object as minor planet 2010 KQ! It would approach the Earth to within 1.28 LD on May 21 and then gradually drift away, in an orbit quite similar to the Earth's (q=0.997 AU, P=396 days, e=0.055).
In the next week, spectral measurements were obtained by Richard Miles using the 2.0 Faulkes Telescope North and S.J. Bus using the NASA IRTF telescope, both on Hawaii and both observers determined independently that the spectrum of 2010 KQ does not match any known asteroid type, but is very similar to space weathered titanium dioxide paint and conclude that 2010 KQ is in fact very likely to be artificial. With further positional observations made in June it appears that the object made a very close approach to Earth in 1975, but it has not yet been possible to definitively match it to a spacecraft launch near that time.
Following on from the (130) Elektra result (TA 551,299), another occultation was successfully captured from Great Shefford, this time of the mag +10.5 star TYC 5573-00543-1 by (80) Sappho on June 4. The drift-scan image shows the starlight being blocked out by the minor planet for 5.5 seconds and revealing the minor planet shining faintly at mag. +11.8. John Broughton's SCANALYZER software was used to reduce the time of disappearance and reappearance (see full details here). At least one other UK observer, Tim Haymes in Maidenhead, Berkshire is also known to have succeeded in obtaining a positive result and other results are expected from France and Italy, which may lead to a determination of the asteroid's shape when all the results are in.
As well as a few very close approaches by newly discovered minor planets (the closest being 2010 JV39 to 0.65 Lunar Distances (LD) on May 26 and 2010 JL88 to 1 LD on May 17) there was also the discovery of unusual object 2010 KQ, originally added to the Minor Planet Center's NEO Confirmation page (NEOCP) on May 16 and observed from Great Shefford on the evening of May 17. Soon after my positions were sent in to the Minor Planet Center, Associate Director Gareth Williams removed it from the NEOCP with a note "was not a minor planet", adding it instead to his "Distant Artificial Satellites Observation Page" at http://www.minorplanetcenter.org/iau/SpaceJunk/SpaceJunk.html and indicated to me that further observations would still be useful. I got another set of measures the next night and sent them in to the MPC as Artificial Satellite positions. The next day all the positions obtained from discovery to May 18 were published in MPEC 2010-K15, announcing the object as minor planet 2010 KQ! It would approach the Earth to within 1.28 LD on May 21 and then gradually drift away, in an orbit quite similar to the Earth's (q=0.997 AU, P=396 days, e=0.055).
In the next week, spectral measurements were obtained by Richard Miles using the 2.0 Faulkes Telescope North and S.J. Bus using the NASA IRTF telescope, both on Hawaii and both observers determined independently that the spectrum of 2010 KQ does not match any known asteroid type, but is very similar to space weathered titanium dioxide paint and conclude that 2010 KQ is in fact very likely to be artificial. With further positional observations made in June it appears that the object made a very close approach to Earth in 1975, but it has not yet been possible to definitively match it to a spacecraft launch near that time.
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