Iridium 920, Gorizont 16, and Raduga 33 over N.A.

From: Ed Cannon (ecannon@mail.utexas.edu)
Date: Sat Jul 22 2000 - 13:43:46 PDT

  • Next message: Stephen.D.LaLumondiere@aero.org: "Re: Iridium 920, Gorizont 16, and Raduga 33 over N.A."

    Last night (early July 22 UTC) Iridium 920 (24871, 97-034C) made 
    a spectacular pass here.  It was a near-zenith southbound track, 
    and I counted more than 80 easy one-power flashes, some of them 
    in negative magnitudes!  Its flash period is about 1.07 seconds, 
    and there was a supercycle on the order of a dozens of seconds 
    where the maxima grew brighter and then fainter and then brighter 
    and then fainter again.  PPAS report:
    
    97- 34 C 00-07-22 03:44:50   EC   92.3 0.3  86  1.074 mag -2->inv
    
    Based on a tip from another observer, using 10x50 binoculars I 
    found Gorizont 16 (19397, 88-71A), a near-geosynch object, 
    flashing last night at least as bright as +4.5 every 93.46 
    seconds.  Mike acquired it in his telescope, and it had a very 
    faint (est. +11) secondary maximum.  It's currently well-placed 
    for observers in the western hemisphere (which is what I should
    have said about 98003 the other day).  PPAS report:
    
    88- 71 A 00-07-22 05:11:44   EC 3551.3 0.5  38 93.46  mag +4.5->inv
    
    Here's a current elset:
    
    Gorizont 16
    1 19397U 88071A   00198.59665363 -.00000089  00000-0  10000-3 0  2900
    2 19397   7.5814  48.9934 0016192 202.0476 157.8955  0.99965139 43595
    
    Heads up, observers in North America!  
    
    Raduga 33 is a flashing object in a very eccentric (failed) orbit 
    of apogee 36,277 km, perigee 470 km, inclination 47.8, orbital 
    period about 10 hours 46 minutes.  It's currently making near-
    perigee passes over North America, and it can be spectacular!  
    Mike McCants and I observed it last night, and I'd estimate the 
    brightest flashes were possibly -3, roughly every 9 seconds or so 
    -- a lot like some flashing Iridiums, SPOT 3, etc.  I checked for 
    the next month, and some of the passes may be even better.  If my 
    stopwatch wasn't deceiving me, the times between primary maxima 
    changed from roughly 9.5 seconds in the NW to about 9.0 seconds 
    in the NE (synodic effect?).  There were also some one-power 
    secondary maxima. (No PPAS yet.)  Here's a current elset:
    
    Raduga 33
    1 23794U 96010A   00201.93614031 +.00000223 +00000-0 +93501-3 0 01362
    2 23794 047.7635 225.1042 7237319 026.2665 357.1192 02.22955476035899
    
    Its mean motion/orbital period causes its passes to miss some 
    nights.  Some software (e.g., Quicksat) won't generate predictions
    for this one.  I don't know if Heavens-Above will predict it either.
    
    Our observing location last night was 30.314N, 97.866W, 280m.
    
    Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA
    
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