Flashing geosynchs over Americas

From: Ed Cannon (ecannon@mail.utexas.edu)
Date: Wed Aug 28 2002 - 05:23:26 EDT

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    For any who might be interested in trying to observe them,
    right now the following known flashing (near) geosynchs 
    are over the Americas -- based on current predictions for 
    Austin, which is a fairly central longitude (Note that 
    they may not be flashing here at the present time.  I've 
    seen all of them at some time or another except for 
    Gorizont 8.):
    11841 80-049A Gorizont 4 (flash period around 148 seconds)
    12089 80-098A Intelsat 502 (p ~ 261)
    14532 83-118A Gorizont 8 (p ~ 57? PPAS 1995 by Jay R.)
    15677 85-035A GStar 1 (p ~ 71; synch.)
    15994 85-076C ASC 1 (p ~ 152; synch.)
    18631 87-100A Raduga 21 (p ~ 124; synch.)
    19483 88-081A GStar 3 (p ~ 144; synch.)
    19621 88-098A TDF 1 (p ~ 31)
    19919 89-027A Tele-X (p ~ 196)
    21533 91-046A Gorizont 23 (p=56)
    21759 91-074A Gorizont 24 (p ~ 91)
    22927 93-071A Telstar 401 (p ~ 127; synch.)
    The ones with "synch." are synchronous and stay on this 
    side of the world (although they may oscillate east and
    west); the rest drift around the world over a period of 
    months.  All of the flash periods except Gorizont 23 
    could be off by some seconds; some of them have annual 
    variations in flash period, I believe.  Some of them can 
    flash to first magnitude; Gorizonts are not quite so 
    bright.  Some flash only a few minutes each night; some
    flash for over an hour or even two hours.
    They are much more easily observed with mounted binoculars
    or telescope, so I guess I'm a glutton for punishment, 
    with my handheld 10x50 observing methods (so far).
    For telescopic observers, there are also a couple of 
    near-geosynch unknowns -- 90005 and 90008 (in mccants.tle 
    file).  I'm not sure how far off they are from their most 
    recent elements.
    Elements for all of these objects are in Mike McCants' 
    mccants.tle file as well his geo.tle and also in Tony 
    Beresford's geoflsh.tle file.
    Note:  What I call "flashing geosynchs" (which are 
    tumbling) should not be confused with "flaring geosynchs" 
    or geosats, which are operational three-axis-stabilized
    geostationary payloads which, around the equinoxes, for 
    brief periods per night can brighten by some magnitudes
    before and after going into the Earth's shadow.
    Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA
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