Re:MiTEx SATOBS

From: Greg Roberts (grr@telkomsa.net)
Date: Fri Jan 23 2009 - 15:28:15 UTC

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    Brad Young had some questions to ask about the MiTEx objects as follows:
    
    >I've been dying to ask a few questions, now that it is appropriate:
    
    Will try and asnwer as best I can . If I talk rubbish Im sure someone better
    qualified will add their bit or pit me right.
    
    >Excuse my ignorance of determining satellite albedo, but this object seems
    >rather bright for a small satellite intended to be easily maneuvered and
    >with stealth capabilities. I assume this is because the solar panels are the
    >major reflective surface, and they must be of some size to support any
    >operations on the satellite (imaging, telemetry, etc.). Perhaps the bird has
    >a much fainter radar image?
    
    Im not 00% sure which object you are referring to so will deal with all
    three. The MiTEx launch placed three major objects in orbit - the two
    small MiTEx satellites and the MiTEx upper stage. For some time we have
    had an object in the element sets that was called MiTEx simply because we
    did not know which one of the three it was. We now know that this is the
    biggest and brightest object so we suspect its the upper stage and is now
    identified as such in the element sets. It is not that easy an object but it
    appears to be flashing at a fairly regular interval and the flashes are quite
    bright so if you watch the predicted position for (say) a few minutes you
    should see flashes which make it easy to track. If the phase angle is correct
    you may not need the flashing because then its fairly easy. If the elements 
    are fairly recent then there is a good chance it will be close to where
    predicted as its regularly tracked.
    
    The object called 91132 is probably a MiTEx proper. Since we have been
    unable to find the other MiTEx object this is most likely the second largest
    object from the launch. I dont know which one it is. It was only found because
    I suspect DSP-F23 would be examined by one of them so all one had to do
    was monitor the vicinty of DSP-F23.  It is NOT an easy object. I have had
    to use relatively long exposures and normally have to wait for the phase
    angle to improve - I found it usually got brighter around phase angle 39
    degrees or so so I would think the magnitude is appropiate for its size-
    whatever the physical size might be. It also appears to exhibit small 
    relatively long period variations of less than half a magnitude variation.
    
    I consider it perhaps one of the most difficult objects I have tracked
    and frankly expect that we will loose the satellite once it passes out of
    range to Peter and myself. If it does another orbit change after this then
    the likely hood of it being found again is remote - unless Scott (say) 
    finds it by accident over your part of the world as he has the most 
    sensitive amateur setup.
    
    >Or, could this be the final stage, with its own panels, as it thought to be
    >a next generation engine with more sophisticated controls?
    
    already dealt with - this is the object currently in the element file.
    
    >Finally, as a "concerned taxpayer" why can we see this thing? And, in the
    >same breath, when? I can't wait for it to maneuver back to the Western
    >Hemisphere.
    
     That I cant answer. Does it really matter if one can see it ? - other than
    perhaps knowing where it is there is not much one can glean from it
    or do about it. I dont know if it was equipped with stealth capability - I
    doubt it.
    
    Finally - "you cant wait to see it"  -- in my case Ill be quite happy never to 
    see it again - its too much like hard work. Its slowly drifting eastward-
    I have seen a suggestion that its may be going to check out the NROL-26
    payload which I understand is MENTOR 4. If it does any orbit change
    then I dont think you stand much of a chance seeing it by the time it drifts
    over to your part of the world. As to the other MiTEx I think we can totally
    forget about it - its probably around magnitude  +15 or fainter.
    
    Hope this answers your questions. I plan to track again tonight and try and
    see 91132 again. If its moved then I could be in for a long search - when I
    first looked for it it took several hours all told plus numerous exposures
    and even then I wasnt 100% confident that I was observing a satellite.This
    was with the 200mm focal length camera- aperture 70mm. I now use the 6
    inch reflector ( aperture 150 mm) as this gives me another 2-3 magnitudes
    gain, but with half the size field of view and even then its difficult and
    impossible with a moon brighter than about 3/4 full.
    
    Cheers
    Greg
    
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