Friday, April 06, 2007

Flaring USA 193 and USA 186

The past 3 nights were very clear and transparent, and with the moon gone, this meant good opportunities for observations in the evening.

Yesterday evening I was treated to some nice flares, and observed USA 193 (06-057A) being very bright for the second time.

The bright appearance of USA 193 was again on a west-southwest pass, just like two days ago. In other parts of the local sky, it remains too faint to observe for me. But like my observation of two days ago, it now again reached magnitude +1.5, easily visible to the naked eye (and camera eye).

The bonus was in a sudden bright flare it produced at 19:37:50 UTC. It was a short but bright flare (about 1 second duration) reaching magnitude -1.5 and with a conspicuous yellow-orange colour. This alas happened some 10 seconds after the end of my exposure.

Now I do know it is so bright when appearing in this part of the sky, I'll start to monitor these south-western passes of USA 193 (earlier I had given up after trying to observe several passes in the northern sky in vain).

Keyhole USA 186 (05-016A) was another target of last evening, and it produced two flares, a slow one to mag. -2 at 20:53:40 UTC and a fast one to mag. 0 at 20:54:10 UTC. Again, not while the camera was opene: I did catch the last fading part of the first flare though, the sat still being mag. +2.5 when my camera opened some 5 seconds after the peak of the first flare.

I had USA 193 some 0.6 to 0.7 seconds late and on-track with regard to Ted's latest elset 07094.84492728, and USA 186 some 3.1 to 3.3 seconds early with regard to Mike's elset 07090.85107920 and notably off-track by 0.05 to 0.08 degree.

During the two nights previous to this I obtained a rich haul of positions on USA 129 (96-072A), USA 193 (06-057A), and Lacrosse 2 & 5 (91-017A & 05-016A). Especially the evening of the 3rd was a bounty, with 15 positions gathered.

Below images from last evening show USA 193 traversing Gemini at mag. +1.5, and USA 186 fading from it's first flare.

(click images to enlarge)

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