RE: Observing the MAST Tether, H-A Error

From: Brad Young (
Date: Wed Apr 25 2007 - 14:33:01 EDT

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    David Anderman said:
    >Perhaps I am missing something, but this object is basically in a sun 
    >synchronous orbit, so it is going to appear at the same local time on 
    >every pass.
    Yes, but if you look at several nights' worth of predictions, you'll see
    that as time progresses, the sat passes over you (Art - winter viewing
    location in Lewisburg WV) slightly earlier each night, "shortening" the
    vertical extent of the shadow. So the satellite passes into sunlight higher
    above you, earlier than the last night. Eventually, this reaches a peak best
    case, which at your latitude seems to be about 80 deg altitude. 
    Then (wouldn't you know it) the passes are too early. So then the sat
    emerges from shadow even more south than before, twilight is too strong to
    see it. This is very typical of sun-synchronous orbits in (northern) summer.
    Then there may be a very short optimum window in fall or spring when the
    earth's shadow is "tipped" enough to see the satellite well, until winter
    when it will probably be very difficult or impossible to see because the
    Brad Young
    TULSA 1
    COSPAR 8336
    36.1397N, 95.9838W, 205m ASL
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