Re: question - brightness of 20638 (ROSAT) + introducing myself

From: Björn Gimle (
Date: Thu Jun 26 2003 - 16:00:11 EDT

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    ----- Original Message ----- 
    > If its not working, its orientation is unknown. In a lot
    > of satellites solar panels are kept pointing at the sun, which
    > means ground observers cant get sunglints. Iridiums are an exception
    > because of operational need. Rob Matson's IRIDFLAR programme
    > gives solar panel flare predictions as well as the MMA sunglints
    > that HA predicts.
    Additionally, if a glinting satellite, that is no longer controlled,
    has acquired a stable rotation, and does not have as many non-aligned
    surfaces as an Iridium, its rotation can be computed and glint
    directions predicted.
    A few observations of its glint RA/Decs to a degree or better accuracy
    (or date+time to matching accuracy) can be sufficient, if in various
    directions, and over a time period while atmosphere and magnetic fields
    don't alter the axis considerably.
    For defunct geosynch comsats, this means that observations can be
    accumulated over a period up to one more years, while the Sun's
    apparent motion contributes to spreading the observation geometry.
    For LEO's the period must be considerably shorter.
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