2003 WT153 (small Aten making close approach, possibly space junk?)
2003 WT153 was discovered with the 1.8m Spacewatch II
telescope on images taken at 07:30UT on 29th November 2003, moving at
over 50"/minute and was followed for nearly 3 hours.
It was put on the NEO Confirmation page later that day but without
any indication of positional uncertainty due no doubt to the good length
of observation obtained by the discoverers.
Nine hours later it was 17th magnitude and travelling at 66"/minute
when first picked up at Great Shefford and was only about 3' from the
Minor Planet Center's search ephemeris position.
To get sharp images suitable for astrometry, because of the fast
motion, exposures were kept to 4 seconds duration and the CCD camera
binned to 2x2 (pixel size 3") to allow more exposures to be obtained
before the object passed out of the field of view. A total of 46 images
were taken during 18 minutes, 12 of which were used to stack together
for the image above. The stacking was done using
Astrometrica and precisely
takes into account the object's fast motion making it appear as a single
small dot but each star in the image is strung out as a series of dots.
Further astrometry was obtained from midnight to 6am UT by Gary Hug
(Sandlot Observatory), James McGaha (Sabino Canyon Observatory) and also
from the Spacewatch II team again,
was issued at 06:42UT on 30th November announcing the newly designated
NEO 2003 WT153.
2003 WT153 was only about 2.3 times as far away as the
Moon at discovery. This had closed to just 2.0 lunar distances by the
time it was imaged at Shefford and it was at its closest to Earth less
than 24 hours later at a distance of just 1.8 lunar distances. With an
absolute magnitude of only +28.0 it is estimated to be somewhere between
6.5 and 15metres in diameter.
Tony Beresford has suggested on the
Mailing List that this object is possibly a piece of man made space
debris. With perihelion very close to Venus's orbit and aphelion at
Earth's, together with its very small size it could be some leftover
part of a probe launched from Earth to Venus in the recent past.