My last two observations of the GRACEs have been steady in a 70 deg altitude W pass, with nice flares to +2 then fading to inv. to the naked eye in a 80 deg altitude E pass. Each acted just like the other, to me. -----Original Message----- From: Gerhard HOLTKAMP [mailto:grd.holtkamp@t-online.de] Sent: Thursday, October 26, 2006 4:22 PM To: SeeSat-L@satobs.org Subject: Brightness of GRACE Satellites A friend sent me two pictures showing the trails of a pair of satellites on related orbits taken at 19:02 UTC, 16-OCT-06 asking for identification. Checking the positions on the pictures and the respective timings I get a perfect match with the pair of GRACE satellites (2002-012A and 2002-012B). What I find strange is that they fluctuate strongly in brightness (even during the 20 sec exposures). The visual report (they were also observed through binoculars) mentioned the leading satellite fluctuating between mag 5 and less than mag 8 (then disappearing) and the trailing satellite was between mag 3 and mag 5. I would have thought that the GRACE satellites have a controlled attitude. Have they gone out of service and are tumbling now? Gerhard HOLTKAMP Darmstadt, Germany ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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