RE: Lunar Iridium Flare #3

From: Matson, Robert (
Date: Mon Jun 12 2000 - 13:32:04 PDT

  • Next message: Alan Pickup: "Decay watch: 2000 Jun 12"

    Hi All,
    This message is to congratulate Ron Lee on his third successful
    observation of a lunar Iridium flare this past weekend.  A lunar
    glint off a satellite is one of the rarest types of satellite
    observation that can be made, and thanks to his diligence Ron
    has three under his belt!  (Bright lunar glints are probably
    more rare than bright satellite transits of the moon).
    > I was concerned that it might not be close to the expected magnitude of
    > 7 since the moon  was just past first quarter.
    Actually, the predicted magnitude was +8.0 according to
    IRIDFLAR 2.1.
    > I am going to estimate that it was 8th magnitude...possibly brighter.
    That's great!  Since you were essentially on the centerline,
    the fact that the flare reached (or perhaps slightly exceeded)
    8th magnitude says that the new lunar phase function in
    IRIDFLAR is quite accurate.
    > I also imagined that the brightness varied a bit but cannot state that it
    > a true effect.
    It was almost certainly a real effect -- as the MMA reflected
    different portions of the moon, you would have seen brightness
    variation from the Moon's non-uniform surface radiance, not to
    mention the effect of crossing the terminator.  In this type of
    observation, Iridium acts like a line scanner, giving you a
    single scan line of a chord across the moon's disk.
    With full moon approaching, the next week is the time to look
    for lunar Iridium flares.  Can anyone else match Ron's feat?
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