"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
Rob,
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 ... :-)
Anthony.
> 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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This archive was generated by hypermail 2b29 : Tue Jun 12 2001 - 16:32:55 PDT