RE: Results observations Cosmos 2421 sat _2010/04/05

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Thu Apr 15 2010 - 18:02:51 UTC

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    Ralf Vandebergh wrote about his image of Cosmos 2421 (06026A / 29247):
    
    > As I reported earlier, when inspecting the first frames of the
    > session, the captured object gave an impression to be pretty big,
    > too large to be just a small piece of a fully fragmented satellite.
    
    The July 2008 edition of Orbital Debris Quarterly News, reported that there
    were three separate fragmentations of 06026A in 2008: in March, April and
    June:
    
    http://orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv12i3.pdf
    
    Your image is consistent with one obtained by John Locker in October 2008
    (in a chance sighting), at somewhat greater range, which indicated that
    06026A remained a large object. It is available on his web page:
    
    http://satcom.website.orange.co.uk/
    
    Jonathan McDowell commented at the time, that the value of such imagery is
    in determining whether the break-up was complete or partial, and possibly
    the mode:
    
    http://satobs.org/seesat/Oct-2008/0207.html
    
    There is other strong evidence that the break-up was partial, and that
    06026A remains largely intact. A query of Space Track's database reveals
    that the radar cross-section of the remains of 06026A is much greater than
    that of any of the hundreds of fragments from the break-ups. 
    
    http://www.space-track.org [Subscription (free) required]
    
    Analysis of Russell Eberst's numerous visual observations before and after
    the break-ups, reveals that its standard magnitude did not change
    significantly:
    
    http://satobs.org/seesat_ref/misc/06026A.pdf
    
    Interestingly, Russell's observations around the date of the initial
    breakup, on 2008 Mar 14, revealed that the object was rotating, resulting in
    a regular variation  in brightness over a period of about 20 s:
    
                                    RA,DEC (1950)   Mag
                 yyyyddmm hhmmss.ss hhmmss ddmmss min max
    0602601 2420 20071007 185153.23 074710+541354 5.5 5.5 0 S
    0602601 2420 20071019 183718.17 023028+423714 2.9 2.9 0 S
    0602601 2420 20071224 180103.96 023927+545438 1.7 1.7 0 S
    0602601 2420 20080109 174119.60 114736+542950 4.4 4.4 0 S
    0602601 2420 20080301 051618.09 124722+264213 2.4 2.4 0 S
    0602601 2420 20080308 192621.99 104109+183659 2.5 3.8 20 R
    0602601 2420 20080309 201158.68 141219+650807 2.1 3.9 20 R
    0602601 2420 20080311 200825.22 162046+521510 4.2 5.7 20 R
    0602601 2420 20080312 191733.10 122939+694608 1.5 2.2 20 R
    0602601 2420 20080320 203501.84 195420+521818 5.6 6.4 20 R
    0602601 2420 20080324 202600.75 175240+565652 5.0 6.5 20 R
    0602601 2420 20080330 201152.45 101712+200236 1.8 3.1 20 R
    0602601 2420 20080520 222119.30 173945+234636 3.1 4.6 30 R
    0602601 2420 20080604 235041.59 235447+552555 4.2 6.1 30 R
    0602601 2420 20080608 233550.17 183310+385026 2.3 2.3 0 S
    0602601 2420 20080610 232823.20 164853+093125 2.5 2.5 0 S
    0602601 2420 20080809 001044.31 065712+705112 4.1 4.1 0 S
    0602601 2420 20080828 223939.20 055255+555700 5.8 5.8 0 S
    0602601 2420 20080904 211830.21 045810+735137 3.7 3.7 0 S
    
    It is the only time that the object was observed to rotate, which suggests
    some relationship to the initial break-up. The rotation began sometime
    between Mar 1 and 8, and the break-up reportedly occurred on Mar 14. The
    rotation apparently ceased by the time of the final break-up, on June 9.
     
    Ted Molczan
    
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