Re: More obs of 05512A (and a note to Rob)

From: b_gimle@algonet.se
Date: Thu Jan 20 2005 - 03:43:53 EST

  • Next message: b_gimle@algonet.se: "Re: More obs of 05512A"

    A week of observations from a single site is not enough to determine 
    the rotation axis, unless the mass distribution of the satellite, and 
    orientation of the panels, is known. Observations from widely 
    differing latitudes, and/or months of observations, and/or finding the 
    "other part of its orbit" would help.
    
    Assuming that the panel normals point 90 degrees from the spin axis 
    (very common) I find an approximate axis near RA 23:25 Dec.-13. This 
    is an (unusual) situation like Superbird-A so the flashes run almost 
    perpendicular to the track, and the RA of observed flashes is nearly 
    independent of observer location. Unfortunately, "the other part of 
    its orbit" in this case is just where the Sun is.
    
    It also resembles Superbird-A in that it has a phase shift in the 
    (short) visibility period. Noting the time (better:position) where the 
    flashes are of equal brightness (or the mid-position of visibility of 
    27 s interval flashes) would make computation of axis more accurate.
    
    For 60N on Jan.21 I find flashes at RA 2:18 to 2:26 Dec. -1.5 
    (22:25-22:33 UTC at 18E).
    For 34S  RA 1:58 to 2:06 Dec.+10 (22:16-22:24 UTC at 18E)
    
    PS: Rob, and SkyMap users, I noticed in my 'StarName.txt' that I have two 
    'zet Ari'
    'zet Ari','', 3.248333, 21.04444, 4.89
    'zet Ari','', 3.263861, -8.81972, 4.80
    The 2nd one should be in Eri !
    
    /Björn
    
    >Från: mike.waterman@web-hq.com
    ...
    >Flashes are actually 2 sets; each set has period (050118) 54.04s. 
    >The two sets overlap for about 4 minutes, during this 4 minutes 
    >the flashes come at intervals of 54.04/2 = 27.02 s.
    >The RA of the last flash has not changed much in 6 days, probably the
    >RA of the first flash has not changed. There must be another part of 
    >its orbit where flashes can be seen, but noone knows where.
    
    
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