Saturday, January 20, 2007

A Lacrosse 4 flare, and a Lacrosse 5 "disappearance trick"

This evening was a very clear evening. The storms of the past days (there was another one last night, and there is yet another one predicted for tonight) have blown the atmosphere very transparent. It was a bit windy and chilly, but observing conditions were perfect otherwise.


(click image to enlarge)

Highlight of the evening was a fine short and bright magnitude +0.5 flare by Lacrosse 4 (00-047A, # 26473) at 18:53:00 +/- 1s UTC, just before it entered into eclipse in Taurus.

Earlier that evening, Lacrosse 5 (05-016A, #28646) did the opposite: it did its "disappearance trick" again at 18:31:27 +/- 2 s UTC, some 1.5 minutes before eclipse entry. The camera was open while it happened: the first of below two pictures, where it is already much fainter than before and disappears. The second picture below was taken a minute before the first, and shows just how bright Lacrosse 5 was at that time (about mag. +1.5).

After it disappeared, it did not re-appear visually (naked eye) or photographically.

Update: Lacrosse 4 (00-047A) was about 0.8s late relative to a two week old elset. Lacrosse 5 was on-time.
After image enhancement in Photoshop, the third image does show Lacrosse 5 as well, but barely. It must have been mag. +4 or fainter.
Bruce MacDonald from the UK reports he observed Lacrosse 5 "disappearing"as well on seesat.


(click images to enlarge)

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