ISS solar transit

From: Thomas Fly (
Date: Sat Jan 31 2004 - 15:16:44 EST

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    I was able to observe a 34-degree elevation solar transit of the ISS from the
    comfort of my own front yard (a first!). Unfortunately, the usual
    unexpected-technical-problems resulted in no usable images.
    The original prediction from Thursday, based upon the Mission Control Center
    ephemeris, had the center line about .2 miles to the SE at 2:07:34.16 PM EST;
    the latest Orbital Information Group TLE (about 6 hours prior to the transit)
    had the center line about .5 miles to the NW, and occurring 2.66 seconds later
    at 2:07:36.82.
    At my latitude, I'm spinning around the earth's axis at about 850 mph, so 2.66
    seconds corresponds to about .63 miles- roughly the shift in transit path from
    one prediction to the other (coming later than originally expected, I would have
    rotated .63 miles farther east than the original prediction, causing the track
    to be that much west of the original prediction- actually, the OIG track is
    almost exactly 1 mile west of the MCC track).
    The transit path width was 2.0 miles, so if the OIG prediction were correct, the
    transit would have been about 25% from the center of the solar disk. Since the
    transit lasted only 1.05 seconds... and the photos didn't work out... it's hard
    to tell, but I got the impression that the transit was at least twice as close
    as that to the center.
    Maybe next time...
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