RE: Iridium flare across the lunar surface

From: Bjoern Gimle (
Date: Wed Jun 13 2001 - 01:19:11 PDT

  • Next message: Ulrich Beinert: "RE: Iridium flare across the lunar surface"

    > > And a dark satellite of 6*6 m would only remove ~25% of the Moon's
    > > light
    > > during 1/600 s. - how long is your camera's exposure time/frame ?
    >     I base my proposed exposures on the phase of the moon as I am
    > looking for a silhouette image cast by the satellite against the lunar
    > surface. I do not want to determine the exposure on the basis of the
    > satellite as any overexposure of the lunar surface will not only destroy
    > the esthetics of the image but it may/should destroy the silhouette of
    > the satellite as well.
    My point here is that if you determine the exposure time to be 1/30 second,
    the satellite will reduce the intensity of a particular pixel only during
    1/600. If it covers 25% of the pixel, that is only 1.2% contrast !
    It also illustrates the dilemma of satellite photography (with a
    "stationary" camera) - there is "no" time for a CCD to accumulate photons
    (except for very wide field, or geostationary satellites)
    (Film also accumulates photons, but less efficiently on long exposures)
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