RE: Iridium flare across the lunar surface

From: Matson, Robert (
Date: Tue Jun 12 2001 - 16:20:31 PDT

  • Next message: Anthony Ayiomamitis: "Re: Iridium flare across the lunar surface"

    Hi Anthony and List,
    > My suspicion is that this [photographing an Iridium flare across
    > the moon] would be an exercise in futility even though we could be
    > dealing with identical magnitudes between the flare and the crescent moon
    > at -8 mag or so (forget about the full moon and the -12.7 mag). What makes
    > the photography of the Iridium flare possible is that we are capturing a
    > object during the 20-40 second exposure.
    A 20-40 second exposure is not necessary.  At typical Iridium
    satellite ranges, the flare would cross the lunar disk in about
    two seconds -- maybe three at very low elevation.  A three
    second exposure of the crescent moon should not be that bad,
    though at high magnification you'd probably want to track
    the moon.
    If you wanted the flare to extend beyond the lunar disk on
    either side, you could expose a little longer -- 5 seconds, 
    say.  If saturation is really a problem, then another option
    would be to use a chopper in front of your aperture.  This
    will turn the flare track into a dashed line (but without
    loss of brightness) while reducing the lunar exposure.
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    This archive was generated by hypermail 2b29 : Tue Jun 12 2001 - 16:22:27 PDT