Re: Iridium flare across the lunar surface

From: Anthony Ayiomamitis (
Date: Tue Jun 12 2001 - 16:32:38 PDT

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

    "Matson, Robert" wrote:
    > 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
    > moving
    > > 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
          We have a difference in semantics. I took the task at hand to mean a
    complete flare intercepting the moon at some point. If a partial flare will
    suffice, then I do agree that a few seconds' exposure involving a very young
    crescent moon would suffice ... however, no comment about the probable
    appearance ... :-)
    > 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.
    > --Rob
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