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 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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