USA 193 non-observation

From: Ted Molczan (sslmolcz@rogers.com)
Date: Mon Jul 16 2007 - 19:35:52 EDT

  • Next message: John Locker: "Re: USA 193 non-observation"

    On 2007 Jul 16, at 07:18:08 UTC, I observed that 06057A failed to appear as
    predicted. 
    
    Predicted magnitude was 4.0. Based on the latest magnitude scatter diagram, the
    object has been observed on occasion to be some 3.5 mag fainter at that phase
    angle, so it could have been as faint as mag 7.5.
    
    I was observing in a clear patch of sky, using 25x100 binoculars, and could see
    easily to mag 8.5 or 9. One of my two reference stars was mag 8.5 and stood out
    clearly.
    
    I observed from site 2701: 43.68764 N, 79.39243 W, 230 m. 06057A was predicted
    to exit penumbra at 07:17:56 UTC, near 14:12, +58:11 (2000.0). I was looking at
    07:18:08 UTC, near 13:26, +63:16 (2000.0). Azimuth was 334 deg; elevation 25.
    Phase angle was 1.9 radians. I started about 40 s before the pass, and waited 2
    min after.
    
    According to Pierre Neirinck, 6 hours earlier, Alberto Rango also did not see
    it, but I am unclear as to the reason. He may have skipped it due weather or
    local obstructions. If it was a no-show, then that may be significant in light
    of my non-obs. I will pass on any clarification that I receive.
    
    The satellite reportedly ceased to function soon after launch, so it would not
    be expected to manoeuvre. Most likely, it just happened to be unusually faint on
    my pass - I have experienced this more than once with the larger KeyHole
    satellites.
    
    That said, until it is seen again, observers may wish to consider beginning a
    search in the event it fails to appear on the coming nights.
    
    Ted Molczan
    
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