RE: Help with identifying a flasher

From: Ted Molczan (molczan@rogers.com)
Date: Tue May 18 2004 - 04:28:43 EDT

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    Geoff Nelson wrote:
    
    > I would like some help with identifying a flashing satellite I saw 
    > this morning.
    > 
    > Observing position 29.7 S 30.8 E
    > Altitude 550 m
    > Time 5:23 SAST ( south african standard time, I can never remember if 
    > that is UT-2 or UT+2)
    
    It is UT+2, i.e. 2 h ahead of UT.
    
    > Satellite observed at about AZ 250 alt 30 dir 190
    > 
    > It came very close to theta lupus if I have my star id correct. It 
    > had passed between alpha and tau scorpio. Please use this to confirm 
    > my alt az and dir as I may have got it wrong. Still pretty mucha 
    > beginner but getting better at astimating alt and az.
    
    I found two possible matches.
    
    Iridium 28 best matches the observed path:
    
    Iridium 28       4.0  1.8  0.0  6.4 d 10.9
    1 24948U 97051E   04136.51680301 -.00000076  00000-0 -34039-4 0  1492
    2 24948  86.3908 125.0284 0002532  84.8638 275.2848 14.34212824349175
    
    Description of 2-line elements: http://www.satobs.org/element.html
    
    On 2004 May 18 at 03:20:30 UTC, it passed between Alpha and Tau Scorpii (az 254,
    el 30). At 03:21:09 UTC, it appulsed Theta Lupi (RA 16:06.6, Dec -36.8 deg,
    2000.0). Heavens Above did not predict any flares from this object near the time
    of the observation. It appears to be in an operational orbit. Has anyone seen it
    flare recently?
    
    MOS 1-A best matches the observed time, and is known to flash brilliantly and
    irregularly:
    
    MOS 1-A          2.4  1.5  1.3  7.0 d 7.21
    1 17527U 87018A   04136.52966743 -.00000027  00000-0  10000-4 0  7557
    2 17527  98.7217 129.4501 0009763 191.7387 168.3552 14.01737546879553
    
    On 2004 May 18 at 03:23:39 UTC, it passed 0.7 deg outside of the line between
    Alpha and Tau Scorpii (az 252, el 31). At 03:24:20 UTC, it appulsed Theta Lupi.
    
    On balance, MOS 1-A seems the more likely candidate. How certain are you that it
    passed between, and not outside, Alpha and Tau Scorpii? How certain are you of
    your site co-ordinates?
    
    Ted Molczan
    
    
    
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