Geostationary problems

From: Greg Roberts (grr@iafrica.com)
Date: Thu Mar 31 2005 - 08:42:55 EST

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    Trying to locate unknown geostationaries is turning out to be more
    difficult than I originally thought as even the geostationary belt is
    overcrowded and sometimes difficult to positively identify the correct
    object. 
    
    The case of objects #26356, #90017 and #90033 is typical:-
    
    #90033 is a new one. When it was first observed by me it was thought to be
    #90017 and an element set was issued for #90017. However when I read the
    original discovery observation by Rainer Kracht it was obvious it was
    not the same object since my observations showed a satellite flashing
    every 2.5 seconds for about 20-30 minutes in the early evening - typical
    of a DSP satellite which rotates 6 times a minute and has four solar panels
    at right angles to one another so hence flashing every 2.5 seconds when
    the sun angle is correct. Rainer's observations were secured when #90017
    underwent a flare. Mike McCants also commented initially that he was having
    problems matching #90017 with my object. Once we realised that it was
    not #90017 the object was given a new number with the following element
    set.
    
     1 90033U 05558A   05073.69509700 0.00000000  00000-0  00000-0 0    02
     2 90033   1.2829  70.5863 0008364 152.4220 207.5780  1.00270000    04
    
    INT2 indicates that the inclination for 90017 should now be about
    4.3 degrees, HENCE all observations reported by me as being #90017
    should now be assigned the number #90033. The amended observations are
    given below
    
    90033 05 558A   0433 F 20050227184028000 17 15 0536413+054932 39
    90033 05 558A   0433 G 20050304183551000 17 15 0551377+055602 39
    90033 05 558A   0433 G 20050310183227600 17 15 0611453+060336 39  +105 05
    90033 05 558A   0433 G 20050310183331900 17 15 0612482+060358 39
    90033 05 558A   0433 G 20050310183515600 17 15 0614336+060431 39
    90033 05 558A   0433 G 20050310183632400 17 15 0615508+060503 39
    90033 05 558A   0433 G 20050310183707000 17 15 0616248+060533 39
    90033 05 558A   0433 G 20050310183812300 17 15 0617309+060553 39
    90033 05 558A   0433 G 20050310183924300 17 15 0618428+060622 39
    90033 05 558A   0433 G 20050314180059000 17 15 0555538+055739 39
    90033 05 558A   0433 G 20050314180148500 17 15 0556484+055821 39
    90033 05 558A   0433 G 20050314181702400 17 15 0612044+060408 39  +070 05
    90033 05 558A   0433 G 20050317175714000 17 15 0603448+060046 39
    90033 05 558A   0433 G 20050317181235300 17 15 0619120+060654 39
    90033 05 558A   0433 P 20050321180907700 17 15 0632005+061125 39
    
    and #90017 has not been observed since discovery and is still lost.
    
    HOWEVER #90033 may not be a new satellite.
    
    I am having a problem with #26356 which is DSP 20. This was last
    observed by someone other than me in 2003, year day 340 as follows:
    
    USA 149 DSP20
    1 26356U 00024A   03340.81678548  .00000000  00000-0  00000-0 0    08
    2 26356   0.4800  17.0000 0010000 108.7720 251.2280  1.00266400    09
    
    Applying INT2 to this orbit the inclination should now be around 1.34
    degrees and RA node around 71.5. This is pretty close to what we find
    for 90033 which makes me suspect that 90033 is in fact #26356. Since
    predictions for both objects place them close together I would expect
    them to both produce bright 7th magnitude flashes with a period of 2.5
    seconds at about the same time of night. This is not the case and there
    is only one bright flasher within a few degrees of predicted positions.
    
    BUT the problem deepens.
    
    On the 10th March I was able to observe a faint flasher close to the INT2
    position for #26356 and I reported a position and a new element set for
    #26356 was issued based on this single observation.
    
    BUT I have been unable to see this object again, probably because its
    relatively faint. I subsequently checked my observation of March 10 and
    measured some additional points which seemed to indicate that the object
    was deviating from the element set issued for that nights observation.I
    am therefore now reasonably convinced that the object observed and
    reported as #26356 by me was NOT #26356. A detailed report of the
    observation is as follows:
    
    "According to my notes this was a flasher, but not a 2.5 sec period,
    flashes being observed at 18h21m53s, 18h22m06s,18h22m35s,18h22m43s,
    18h22m55s,18h23m14s,18h23m27s,18h23m37s,18h24m35s,18h24m44s,18h25m14s
    (all UT)
    
    The next satellite observed was reported as #90017 and my notes say
    "found it at 18h32m, regular flasher and observed till 18h39m ,and
    position reported was
    
    90017    18h32m27.6s  UT  RA 06h11m45s,Dec +06d03m36s
    
    After failing to observe #26356 subsequently on several occassions I
    re-examined the DVD recording made on March 10th and my notes say:
    
    Okay had a good look at the DVD - they are definately (ie 26356 and 90017)
    not the same objects. The first one, which I will call 26356 has a brief
    flash - sometimes single but also sometimes a double flash over a period
    of about 2-3 seconds, then invisible till the next flash or flashes
    ( remember I am looking at images that have been integrated or exposed
    for 0.96 seconds so I do not know when in the exposure the flash started
    or stopped). Looking at the approximate times of flashes I think one could
    suspect a period of about 10 seconds, so this may well be a DSP. The
    flashes were generally weak, at around magnitude 11 to 12, but sometimes
    as bright as about 10th mag. More positions were measured and this showed
    that the object was deviating from the predicted path for 26356, whose
    elements had been based on my observation of this date at 18h21m41s
    at which time the predicted position was the start of the predicted track
    and "spot on" track. However as time progressed the satellite moved
    steadily away from the predicted track, so the elements for 26356 are
    suspect as the inclination does not appear to match. Here are the extra
    positions measured and not reported till now:
    
    26356 00 024A   0433 G 20050301191824000 17 15 0603326+055944 39
    26356 00 024A   0433 G 20050310182013400 17 15 0542080+055030 39
    26356 00 024A   0433 G 20050310182041100 17 15 0542366+055106 39  +105 05
    26356 00 024A   0433 G 20050310182111800 17 15 0543071+055137 39
    26356 00 024A   0433 G 20050310182204600 17 15 0543594+055250 39
    26356 00 024A   0433 G 20050310182233400 17 15 0544288+055320 39
    26356 00 024A   0433 G 20050310182354000 17 15 0545490+055459 39
    26356 00 024A   0433 G 20050310182434100 17 15 0546284+055547 39
    26356 00 024A   0433 G 20050310182515600 17 15 0547120+055639 39
    
    So my "problem" at the moment is that I suspect #90033 is in fact #26356,
    #90017 has NOT been recovered, but what was observed at the location of
    #26356 but not seen subsequently - something that has just "struck me" -
    does the observation of #26356 fit with #90017 ? - I am not an orbit
    analyst so leave this to the experts :-))
    
    Cheers
    Greg
    
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