RE: ISS observation

From: Matson, Robert (ROBERT.D.MATSON@saic.com)
Date: Mon Jan 08 2001 - 12:18:22 PST

  • Next message: Matson, Robert: "RE: Re-entering"

    Hi Tony,
    
    > At Rob Matson's request, just observed ( at 18:22 UT Jan 5,
    > 04:52 jan 6 local time) a high pass of the ISS.  Maxium
    > elevation 67 degrees in NW at 18:22:20UT. No glints just a
    > smooth brightening and fading.  Maximum  brightness was
    > -2.5 rather than Heavens-above's prediction of -0.6.
    
    Thanks, Tony, for your observation!  Actually, I consider
    your observation a partial success, or at worst indeterminate.
    My model predicted a peak magnitude of -2.4 at 18:22:42 as
    your off-axis angle from the specular direction was 6.3
    degrees.  (The peak would have been rather broad -- I have
    magnitude -2.0 at 18:22:30, and it has only dropped to
    -1.3 at 18:23).
    
    In contrast, excluding specular effects, SkyMap shows
    the peak magnitude would have been only -0.8 at 18:22:18,
    or roughly 25 seconds earlier.  At the time of the
    predicted (but broad) glint peak at 18:22:42, the non-
    specular predicted magnitude was -0.5.
    
    So the follow-up question for you is when do you estimate
    your peak brightness occurred?  If you don't recall when,
    then ~where~ will work just as well.  If the peak occurred
    more than 10 seconds after culmination, I'd say we'd
    have a success.  (Stay tuned for a report from another
    Seesat regular on a DEFINITE success...)  --Rob
    
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