Thursday, 5 April 2012

The Nanosail UNID (10-062X) and Lacrosse 5 brightness variation

When NASA's experimental solar sail Nanosail-D was launched by a Minotaur IV rocket in 2010, it was not the only object this launch brought into space. A number of other, classified objects were part of the same launch.

Now Nanosail-D has decayed, four of these objects (RAX, OREOS, FASTSAT, FAST 1) are being tracked by amateur trackers. One additional object of the launch that is being tracked, however cannot be identified reliably with one of the payloads so far. It could be a payload, or a rocket part from the launch. Dubbed the 2010-062 UNID (10-062X) or "Nanosail UNID" by amateur trackers, it is an object near magnitude 4-5, stable in brightness.

The footage above (WATEC 902H + Canon EF 2.0/35mm lens) shows it passing through the tail of Uma (bright stars are epsilon Uma and delta Uma) on April 1st 2012.

I also filmed Lacrosse 5 (05-016A) that evening. The erratic brightness behaviour of this satellite has featured before on this observing blog. Using footage from the April 1st pass and LiMovie, I reconstructed the brightness curve below, showing a  flare at 20:09:14 UTC and a general quite irregular brightness behaviour with what looks like several small peaks. At 20:09:30 UTC, it appears to do it's typical "disappearance trick" again, dropping rapidly in brightness in just a few seconds of time (note: shadow entry was not before 20:12:00 UTC). The profile is very similar to profiles for Lacrosse 5 which Philip Masding previously obtained, also showing the "disappearing trick" being preceeded by a flare.

click diagram to enlarge

The video footage this curve is based on, is this footage (shot with a 12mm wide-angle lens):

More objects were observed the past few nights. Among them USA 129 (96-072A) and Lacrosse 4, while CCD imagery of Prowler (90-097E)  using the "remote" Rigel telescope of Winer observatory was obtained again as well.

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