South Pole Iridium Flare Marathon

From: Gerhard HOLTKAMP (
Date: Fri Aug 26 2005 - 14:44:56 EDT

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    Hi everyone,
    this is especially for whoever likes geometrical problems. Right now observers 
    at the South Pole are in the middle of an Iridium flare marathon: From 
    18-AUG-05 until 8-SEP-05 (a period of three weeks) there will be Iridium 
    flares brighter than mag 0 every 9 minutes. They all come from satellites of 
    one particular orbit plane (Iridium 82 - 1998-051A is a member of that 
    plane). The flares will peak above mag -8 for 48 hours on 27/28 August. And 
    just at that time satellites from a second orbit plane (Iridium 67 - 
    1998-021F is a member of that plane) will flare up to mag -6. But while the 
    flares from the first orbit plane last for three weeks, the second orbit 
    plane will flare above mag 0 for only two days.
    Now why do flares from the first orbit plane last so much longer than those 
    from the second one? Each Iridium orbit plane precesses the same as they are 
    having similar orbit parameters. I guess it will come down to a very 
    fortuitious geometry between the position in the sky where the flares occur, 
    the position of the sun and the South Pole all that paired with the 
    precession of the orbit and the movement of the sun as well as the mirror 
    (MMA) used (flares from the first orbit plane come from the right MMA, flares 
    from the second one come from the left MMA). When I went to bed last 
    night and tried to think about the details of this I immediately fell asleep 
    - works better than the strongest sleeping pill!
    Gerhard HOLTKAMP
    Darmstadt, Germany
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