Chang'e 2 booster

Here is a lightcurve derived for 2010-050B which appears to be the booster that helped launch the Chinese Chang'e lunar mission. It was on the NEOCP for a while and looks like it will be visible for a while at least as a NEO-like distant artificial satellite. The lightcurve is from 246 exposures taken on 25 Nov. which shows a 26.89 sec rotation period with an amplitude of about 3.0 mags and I interpret it as representing a generally regular, elongated object, but as the "dark" ends point towards us, one end produces a bright (2+ mag) flash, lasting just 2.6 seconds centered at about phase=0.56 and the other end produces a much fainter flash (<1 mag.) for about the same duration at phase=0.06.

Lightcurve of 2010-050B (the booster for the Chinese Chang'e mission)

2010 September notes: 2010 RX30, 2010 RF12 and the pair 2010 RX3 and RY3

Good weather from Aug. 29 to Sept. 17 resulted in a run of 17 out of 20 nights usable for observing, but unfortunately the last half of the month could only manage three. There was plenty of NEO activity in early September, with a number of close approaches:

2010 QG2 had been discovered on the last day of August by LINEAR and was followed on the nights of Sept. 1 & 2 at mag +17.0 as it passed by at 5 Lunar Distances (LD).

The Catalina Survey Mt. Lemmon station discovered two small asteroids within about half an hour of each other on Sept. 5th and both came closer than the Moon three days later. 2010 RX30 is probably about 11 meters in diameter and passed at 0.64 LD on Sept. 8th at 09:51UT, closely followed by 2010 RF12 (~7 meters dia.) which came as close as 0.2 LD or just 6 Earth diameters at 21:12 UT the same day.
2010 RX30 was imaged on the nights of 5th, 6th and 7th Sept. and on the last night was 16th mag. and moving at 160"/min, at a distance of 1.2 LD. It was last seen by Richard Miles using the 2-m Faulkes Telescope North just half an hour before closest approach by which time it was 14-15th mag. and moving at 520"/min!
2010 RF12 was well observed by many people in the run up to its fly-by and again was tracked from Great Shefford on the nights of 5th, 6th and 7th September. When last seen, before clouds moved in it was also 16th mag. but moving slower than 2010 RX30 at 37"/min and at a distance of 1.1 LD. David Herald in Australia was the last to report positions for it, 11 hours before closest approach and by then it was 14th mag., moving at 168"/min at a range of 0.5 LD.

Just before month end, 2010 SK13 passed by at 0.7 LD and was observed on the night of 29th Sept. at mag +17 when it was 2.4 LD away. It was closest at 15:58UT on the 30th but was last reported 7 hours earlier from the Magdalena Ridge Observatory in New Mexico, before it had crossed within the orbit of the Moon.

Probably the most unusual discovery was made on Sept. 2nd, again from Mt. Lemmon. Two objects were put on the NEO confirmation page travelling at almost the same speed and in the same direction, one moving at 10.6"/min in p.a. 77.5°, the other at 10.8"/min in p.a. 78.5°. Added to that, they were of similar brightness and only 1.5° apart in the sky. They were designated 2010 RX3 and 2010 RY3 the day after discovery but unfortunately they were already mag. +21.2 and +21.4 and within a day or so of their brightest for this apparition. I managed to record both on two nights, but they were always very difficult objects and both were lost after only 7 days. The orbits for both are necessarily still somewhat uncertain after such a short arc but the elements are very similar and indicate that the two objects were probably gravitationally bound in the recent past. The JPL Small-Body Database Browser at http://ssd.jpl.nasa.gov/sbdb.cgi gives the following orbits for the two objects:

2010 RX3	2010 RY3
T = 2010 Sep.29.70 ±0.04 d	T = 2010 Oct.01.85 ±0.04 d
q = 1.00365 ±0.00009 AU	q = 0.99181 ±0.00004 AU
Q = 4.26 ±0.05 AU	Q = 4.29 ±0.05 AU
e = 0.619 ±0.005	e = 0.624 ±0.005
a = 2.63 ±0.03 AU	a = 2.64 ±0.03 AU
Peri = 202.26 ±0.02°)	Peri = 206.06 ±0.02°)
Node = 172.69 ±0.03°)2000	Node = 171.99 ±0.02°)2000
Incl = 3.89 ±0.02°)	Incl = 4.44 ±0.02°)
H = 25.06	H = 25.07

2010 August notes: (105) Artemis occultation, NEO discoveries and recoveries

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.

2010 July notes

July was very disappointing with only 21 hours observing, spread over 10 rather poor nights, my worst monthly figures since June 2007 and my worst July since the observatory started operating in May 2002. The best of the skies were at the beginning of the month.

Early on 4th July the 1.5-m scope on Mt. Lemmon picked up Apollo 2010 NG, over 15 Lunar distances (LD) from Earth, but due to pass at just under 6 LD on July 13. Although probably only about 30 meters in diameter it was predicted to reach mag. 17 as it plunged far south in the days leading up to its close approach. I caught it on the nights of July 4, 6 and 9 before it went out of view, the last night it was moving rapidly south, at a declination of -25 and only 10 degrees above the horizon.

One other object which was followed for three consecutive nights in early July was 2010 NB, a 19th mag LINEAR discovery from July 1. By July 3.0 when I first observed it, it was moving north, at a high northern declination and fading fast - it had evaded discovery during the last week of June when it was at its closest and was already a magnitude fainter when LINEAR picked it up. It was last detected by the Astronomical Research Observatory, Westfield, USA on July 6.2 at magnitude +21.4.

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.

2010 March notes: WISE and Pan-STARRS

Generally poor observing conditions throughout March hampered observing but a number of new NEOs were followed, after they had been posted on the Minor Planet Center's NEO confirmation page (NEOCP), which is now at this new address:http://www.minorplanetcenter.org/iau/NEO/ToConfirm.html

Although the majority of new objects in March were discovered as usual by the Catalina Sky Survey/Mt. Lemmon telescopes, the WISE Infrared Space Telescope has started to make a significant contribution. About 1 in 5 of the objects added to the NEOCP in February and March were WISE discoveries, however, these are likely to be "extra" objects. WISE is in a polar orbit and scans a great circle aligned 90 degrees from the Sun and so most if not all of the WISE discoveries are unlikely to have been found at that time by the other NASA funded surveys that tend to cover the opposition area of the sky, though some may eventually have been picked up by the ground based surveys as the objects tracked across the sky.

WISE uses a 16" mirror to observe in four bands in the infrared and converting the measured IR brightness into likely visual band magnitudes to be included on the NEOCP for Earthbound observers is tricky, some objects being relatively bright in the IR and others fainter. Many of the WISE discoveries are being listed with V magnitudes of 22-23 but some are brighter than these  estimates would indicate and potentially in reach of amateurs.

Going after a WISE discovery with amateur equipment involves taking a large number of exposures and having to be resigned to the fact that there is a good chance that the effort will be for nothing if the object is too faint to be detected. However, WISE's IR eye is very good at picking up comets just as IRAS was 27 years ago. So if a WISE object is bright enough to be picked up it is well worth checking the images for signs of cometary activity. Three out of five WISE objects detected in March from Great Shefford turned out to be comets (P/2010 D2, C/2010 D4 and C/2010 E3).

The first Pan-STARRS 1.8-m telescope on Hawaii with its 1.4 gigapixel camera has also started submitting many hundreds of positions of minor planets to the Minor Planet Center this year and it can't be long before this gives all the other surveys some keen competition too.

2010 January notes: 2010 AL30, 2010 AF40, 2010 BC, 2010 BU2 and 2010 BG5

A few relatively bright, newly discovered Near Earth Asteroids were followed during the month but the most newsworthy object 2010 AL30 passed just 0.33 Lunar Distances (LD) from Earth on 13th Jan. with the UK unfortunately shrouded in cloud. It was well observed from many other locations around the world and was last reported from Reedy Creek Observatory in Australia at 11:00UT on the 13th, less than 2 hours before closest approach and moving at 840"/min!

Less dramatic, 2010 AF40 had been discovered from Mt Lemmon on 12th Jan. and was followed from Great Shefford on the 17th and 19th. On the last date it was 16th mag., moving at about 40"/min and about 5 LD from Earth. It was last reported later on the 19th from the Sormano Observatory in Italy, going unobserved when it passed Earth at 2.3 LD about 35 hours later.

A Catalina discovery 2010 BC was followed on 16 and 17th Jan. at 17th mag. but it approached to within 8 LD by 24 Jan, maintaining 15th mag. for 4 nights, unfortunately during another cloudy period in the south of the UK.

More luck was had with the LINEAR discovery 2010 BU2, observed on three nights at the end of the month when it passed at 6.5 LD, reaching 16th mag. but with interference from the full Moon. Another LINEAR find, 2010 BG5 was moving almost due north at discovery on 25 Jan. and had already reached a dec. of +72°. It passed less than 4° from the North Pole on 28th and I picked it up in the early evening of 29th and 30th Jan, by which time it was moving at 40"/min. heading almost due south towards the northern horizon. It was at 6.6 LD and within a day of closest approach, but with the phase angle 95° and increasing it was fading fast at 19th mag.

2009 December notes: 2009 WZ104, 9U01FF6, 2009 observing statistics

December provided a reasonable amount of observing time but the number of NEOs discovered by the surveys was much reduced, 34 new objects compared to the 116 they picked up in November, so NEO follow-up work was quieter than of late.

As well as following objects on the NEO Confirmation page, the opportunity was taken to follow 2009 WZ104 on several nights to try and determine its light curve. This is an Aten discovered on Nov. 25 by the Catalina Sky Survey and was brighter than 17th mag. for the first two weeks in December. However, not enough coverage was obtained to be able to find an unambiguous period, but it is likely to be longer than 6-8 hours.

The unusual artificial satellite 9U01FF6 mentioned last month in TA Vol 46 No 548 p211 (2009) which is in a 30+ day, very elongated orbit, taking it as close to us as 5 Earth diameters and about twice as far as the Moon at apogee, was picked up again on Dec. 27, three days before perigee. It was only 5" from the prediction calculated with FindOrb using positions from the previous two returns and taking into account Solar Radiation Pressure. Unfortunately the weather stopped any further observations but it should be visible next on the night of 6th Feb. 2010 and then in March a relatively long apparition, from the 11th-15th.

2009 overall was an exceptionally good year for observing at Great Shefford, producing the best observing figures since my observatory was commissioned in May 2002. Several statistics follow, with the previous best figures and year in parentheses: The most nights used (202 vs. 183 in 2003), the most hours spent at the telescope (938h vs. 838h in 2005), the largest amount of time the CCD shutter was open (24d 00h vs. 22d 03h in 2007) and far and away the largest number of images taken in a year (148,361 vs. 92,025 in 2007). That last statistic is in part to do with more Minor Planet photometry being done in 2009 than before, with many objects being followed for long periods of time, collecting many images during a night. The total number of images taken since 2002 passed the 1/2 million mark during the year and now stands at 570,575.

2009 generally seems to have beaten my previous records by 8-12% all round. Lets hope 2010 doesn't let us down!