Re: NOAA-13 question

From: Bram Dorreman (bram.dorreman@gmail.com)
Date: Thu Jul 15 2010 - 16:02:38 UTC

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    Ralf Vandebergh wrote:
    I last night sighted an interesting flashing sat with binoculars through the
    Big Dipper which turned out to be NOAA-13 as the closest candidate.
    It showed a nice regular flashing pattern with a period of no longer
    then 1 - 1.5 seconds, with the flashes as the only visible points.
    
    What is known about flashing of NOAA-13 and other observations.
    
    My response:
    Here follow the PPAS-observations since last year's spring.
    
    93- 50 A 09-03-26 21:10:48.4 AR  133.7 0.2  12 11.14  F'aaF'; b39)
    93- 50 A 09-04-15 20:39:53.5 AR   86.2 0.5   8 10.78  A; +7.5->inv; b38)
    93- 50 A 09-04-22 22:43:03.8 BD   85.5 0.2   4 21.4   +3.0->inv; b40)
    93- 50 A 09-04-28 21:31:42.3 BD   84.6 0.2   4 21.1   +3.5->inv; b40)
    93- 50 A 09-04-28 21:31:58.4 BD  111.2 0.2  42  2.65  A; +3.5->inv; b40)
    93- 50 A 09-04-30 21:11:33.3 AR  263.5 0.3  25 10.54  Aa; +3.5(6.5)->inv; b43)
    93- 50 A 09-05-17 21:14      BD   30.7 0.2   3 10.2   F +3->inv; b41)
    93- 50 A 09-05-21 22:10:52.2 BD   95.1 0.1  37  2.57  A; +4.8->inv
    93- 50 A 09-05-29 22:19:21.1 BD  175.1 0.1  69  2.54  F=>A; +0.2->inv
    93- 50 A 09-06-19 21:38:22.3 AR  287.4 0.3  29  9.91  F; +4.5->inv; b42)
    93- 50 A 09-08-31 22:45:44.8 BD  127.1 0.2  14  9.08  fAF=>AAF; +1.8->inv
    93- 50 A 10-03-28 21:14:11.5 AR  155.2 0.3  21  7.39  F; +6->inv; b44)
    93- 50 A 10-04-09 20:33:35.3 BD   35.6 0.2  10  3.6   F; +5.5->inv
    93- 50 A 10-05-05 01:00:00.0 BD    8.0 2.0   1  8.0   Aaaa; +4.5->7.5
    
    This inactive weather satellite in sun synchronous orbit is rotating about one
    or more axes. It appears to us as a flashing object with varying magnitudes
    and different flash periods, possibly depending on its attitude with respect to
    sun and observer. When I follow this object long enough and compare the
    different flashes I sometimes see a flash pattern repeating about every
    10 seconds. Sometimes I see one flash every 10 seconds, sometimes I see
    two flashes or even four in the same time interval.
    
    Since all flashing satellite observers are living in the northern hemisphere
    and this object is in sunlight during the summer half year we have collected
    observations made in the months March - September only.
    
    All these observations and more, with short comments such as flash pattern and
    magnitudes and references to a comments file are available on
    Mike McCants website: http://www.io.com/~mmccants/bwgs/index.html
    
    You can also look at
    http://kunstmanen.vvs.be/php/satflash.php
    and enter 93- 50A in the query dialog box left of the "query verzenden" button.
    However when I tried this myself to day it did not work.
    I know the VVS-people are rebuilding their website so this may be the reason
    for this not functioning.
    
    NOAA 11 has a similar behaviour.
    
    These two objects can surprise you by a single negative magnitude flash.
    When you are able to find them back using binoculars you will see a lot
    more flashes.
    
    Site 4160: 51.27931 N, 5.47683 E (WGS84), 35 m
    Bram Dorreman (PPAS collector)
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