Re: Unexpected and Unidentified Satellite Flare

From: Björn Gimle (b_gimle@algonet.se)
Date: Tue Dec 03 2002 - 09:14:31 EST

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    ...
    > The flare is probably -2 magnitude within five degrees
    > southeast of Epsilon Cassiopeiae.
    > ...
    
    I am pretty certain this was Iridium 55, predicted by IridFlar/SkyMap at
    mag +0.0 23:25:22 UTC (18:25:22) 2002-12-02, 5.4 degrees from eps Cas in
    DIRection=162 degrees ("5 o'clock") rel.to local vertical.
    
    This is excellent agreement with above, if Dave's "southeast" means 135
    deg ("4:30") rel to local vertical.
    
    However, observations should include what reference system is used -
    other observers may mean "relative to celestial N" ie at about 3.5 deg
    lower declination and (at this +63 deg decl) 0:30 lower RA.
    
    Yet others (all too frequently) mean "in the direction of a great circle
    going from NW on horizon through the observed spot down to the SE
    horizon" which is quite difficult to determine/visualize/compute
    accurately, especially if looking at a photograph or through binoculars.
    
    Although there is little doubt in this case, other observations should
    also include the direction of satellite motion (in this case 220
    degrees), and if possible a speed estimate ("distance deta-epsilon
    travelled in 12 seconds").
    
    I am composing an image of stars, tracks and angles involved to send to
    Dave K.
    
    Ir 55 is in an operational orbit, so you should also find it at
    HeavensAbove.
    
    Iridium 55       4.0  1.8  0.0  6.5 d  8.9       780 x 776 km
    1 25272U 98019A   02325.59513736  .00000019  00000-0 -13878-6 0  8696
    2 25272  86.3981 350.9521 0002389  59.6468 300.4955 14.34218419243316
    
    
    -- bjorn.gimle@tietotech.se (office)                         --
    -- b_gimle@algonet.se (home)  http://www.algonet.se/~b_gimle --
    -- COSPAR 5919, MALMA,    59.2576 N, 18.6172 E, 23 m         --
    -- COSPAR 5918, HAMMARBY, 59.2985 N, 18.1045 E, 44 m         --
    
    
    
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