Sunday, 9 March 2008

USA 129, and an unknown object

Friday evening was clear, albeit with occasional wisps of cirrus traversing the sky. Back home from my new job in which I started last week, I could do some observing again.

First I tried to observe two predicted zenith passes of USA 193 debris, but didn't spot anything.

Next target was Lacrosse 3 (97-064A). I selected a star field close to beta Umi near RA 15:00, dec +76 45', through which Lacrosse 3 would pass at 19:46:30 UTC (March 7).

Just before the expected appearance of Lacrosse 3 in the FOV, suddenly a very fast object of about mag. +7.5 crossed through the lower part of the (4 degree) FOV. It moved west-east and roughly parallel to the predicted Lacrosse track. It was very fast, maybe even moving as fast as 1.5 degree/second. It caught me completely by surprise, so it took me some time to realize what happened and try to fix an approxiate time. With a plus-minus of say 20 seconds in time, the resulting position (in IOD format) is about:

99999 08 999A 4353 G 20080307194600000 17 75 1511063+756260 36 S

Given the fast speed and general direction of movement, my thought was immediately that this could be a piece of USA 193 debris. It doesn't match any of the published catalogued debris pieces though. And according to Ted, it would be somewhat too far from the expected plane of these fragments. So the object remains unidentified.

Some 30 seconds later Lacrosse 3 sailed into the FOV.

Other objects tracked that evening were all of the NOSS 3-4 objects (07-027A, B and C) including the Centaur rocket, the NOSS 2-3 objects (96-029C, D and E). I also observed two of the KeyHole photo-reconnaissance satellites: USA 129 (96-072A) which initially was bright, and USA 186 (05-042A). They were all early, especially USA 129.

I catched the latter on photograph too, while it crossed close to Castor and Pollux in Gemini, being about mag. +0.5:

(click image to enlarge)

All in all, 16 positions were logged on 10 objects this evening, two of which were camera positions, the rest was visual. The visual position obtained for USA 129 and the two camera positions agree well.

1 comment:

Thomas Wehr said...

I've prepared an overview of the already catalogueed pieces of USA193 which can be watched at