RE: catching a low flying satellite + Long-range obs

From: Tony Beresford (aberesford@iprimus.com.au)
Date: Wed Jul 31 2002 - 04:18:28 EDT

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    At 16:37 31/07/02, you wrote:
    >Hi everybody,
    >
    >
    >The other night, July 27 0910:20 UTC, I was randomly scanning the NE sky
    >with my 9x63 binoculars. I picked up a very dim, slow-moving satellite,
    >which I (in my inexperience and ignorance of any nearby constellations)
    >estimated to be maybe mag 7-8 or so. The only match I can find with
    >alldat.tle, and FindSat + Virtual Sky (for direction) is GPS 2-17 r2
    >(22277). Its range was about 7500km, H-A mag 9.9, the sky was quite
    >clear (haze-wise) and not light-polluted (but not completely cold
    >either). Could I have seen something this dim and distant?
    Hello there Adam. If the object was as dim as predicted, probably
    not, as I suspect the limit of 9x63 binocs is around mag 8.
    However if the third stage rocket had as much as 1/6 of a square inch
    (about 1 sqof mirror like surface of 100% reflectivity, in the right orientation, it would have been possible. Since in general the greater the time interval 
    since launch the slower the rotation rate, the greater is the chance
    that such a sun glint will last long enough to produce such an observation.
    Perhaps others on this list might be able to suggest the length of
    time involved for a sun glint from an locally fixed orientation in the GPS transfer orbit, as compared to an Iridium flare. From reports on flares from Molyniya orbit objects, I suspect its around a minute or so.
    Tony Beresford
    
    
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