Re: Unidentified Flasher

From: Björn Gimle (b_gimle@algonet.se)
Date: Mon Feb 25 2002 - 16:13:26 EST

  • Next message: Alan Pickup: "Decay watch: 2002 February 25"

    No bright (mv) satellite found within +-4 min (tdiff) and 11 degrees (Sep)
    in file satbase.tle
    (FE) should be around 10 for a descent to the N - I am constantly advocating
    against the latter way of describing direction of motion:
    The most accurate way is scetching the path among stars in the
    neighbourhood; or describing distance and direction to nearby stars (even
    better to pairs of nearby stars); expressing motion as if you held the face
    of a clock to the satellite, with 12 up, 6 down (local vertical). This is
    what FE in IDsat does - I prefer it the way QuickSat does (Dir = (FE-6) in
    degrees; 10 ~ 120 deg). You should also try to estimate the speed of
    apparent motion - if no stellar references use your (specified) binocular
    field-of-view; if no tool available, count the seconds, and use the spread
    between your thumb and index finger tips as about 14 degrees. The time
    estimated is to be compared to (Vang) deg/s in IDsat.
    
    In classfd.tle IDsat finds a DMSP - they usually don't flash regularly, but
    can give one or two Iridium-like flares. DMSP B5D2-8    95015A   #23533 was
    very nearly in NW (315 deg) at 18:50:00, but at 17 deg altitude, moving down
    (in Dir=120) between alpha/gamma Cygni. (Both IDsat output files, and SkyMap
    screen shot sent to Marcus)    :
    
    99000 99 000A   5003 P 20020222185000000 17 25 2149000+510000 99  +010 10
    
    NORAD 2-line elements source file : \tle\classfd.tle
    
    Maximum time difference = 240 s
    Maximum angular separation = 12 deg
    
                                    tdiff   Sep     mv    RCS  Range Trk  FE
    Vang  Age    Unc
         Name       Desig   NORAD     s     deg    pred   m^2   km   deg hour
    deg/s days    s
    -------------- -------- ----- -------- -----  ------  ---- ----- --- ---- --
    --- ---- -------
    DMSP B5D2-8    95015A   23533    42.66 10.21   9.2 v  5.61  1817 343  9.9
    0.19   23     3.7
    
    DMSP B5D2-8
    1 23533U 95015A   02031.27373439 0.00001200  00000-0  63040-3 0    02
    2 23533  98.8536  43.4978 0007000   6.1610 353.8390 14.14159424    09
    
    /Björn
    
    -- 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         --
    
    ----- Original Message -----
    > 22nd Feb.at sometime about 18:50 UTC,I saw a flasher low(about 30deg
    > elevation)in the NW,heading and descending N.The flashes were at least
    mag.0
    > and the flash period was at least 5 seconds.I appreciate that this data is
    > so infuriatingly approximate that it's going to make any kind of ID
    > tricky(and I'll continue to strive for greater accuracy with my
    
    
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