RE: lunar iridium flare

From: Matson, Robert (
Date: Thu Oct 12 2000 - 17:35:10 PDT

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    Hi Richard,
    Congratulations on your first lunar Iridium flare!  Based on
    your coordinates and recent TLEs for Iridium 28, the predicted
    time of your lunar flare would have been 20:36:07.3, so if you
    saw it starting at 20:36:11, that's probably within the margin
    of error on the spacecraft pointing.
    > The time scale of the event was similar to a nearly central
    > sun-illuminated flare.  One odd thing - the flare was distincly
    > orange.  Sun-illuminated flares all seem quite whitish, and the
    > moon is not a redder source than the sun.  Has anyone else
    > noticed this with lunar Iridium flares?
    I think Ron Lee is the only other one who has ever seen one
    (he's seen several), but I don't recall him mentioning any
    color.  One point of concern for this observation is that the
    satellite became sunlit (penumbra) starting around 20:36:35 --
    only about 25 seconds after your observation.  That should
    be plenty of time to rule out solar shenanigans, unless IR28
    was hugging the terminator line.  Even so, if you were seeing
    a diffuse sunlight reflection (rather than a specular lunar
    reflection), you wouldn't expect the brightness to ramp up
    and then back down.  It would just have gotten brighter and
    stayed that way.
    Too bad you didn't continue to follow IR28 with binoculars.
    Turns out it produced a magnitude 2 regular flare at 20:40:15
    about 22 degrees above your northern horizon!  A solar and
    lunar flare on the same pass, 4 minutes apart!
    And just to add to the coincidences, I have a -7 flare from
    Iridium 28 predicted for MY location tonite at 20:11:16 PDT.
    IR28 has sure been busy... --Rob
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