Re: Geometry for flashes from DSP USA 39

From: Tony Beresford (
Date: Wed Mar 26 2003 - 21:07:11 EST

  • Next message: paul: "8305 obs 27mar ut"

    At 08:08 27/03/03, Michael McCants wrote:
    >I posted:
    >>Rainer reported that he observed bright flashes from this object
    >>at 22:50 for only two minutes.  The RA at 22:50 on March 21 is
    >>about 11 Hrs 15 Mn.  This gives a sun-satellite-earth angle of
    >>about 170 degrees and a half angle of about 85 degrees.
    >Of course this should read:  "This gives a sun-satellite-earth
    >angle of about 10 degrees and a half angle of about 5 degrees."
    >The Earth is about 10 degrees in radius and the DSP rotates around
    >an axis that is pointed towards the Earth so that the Earth is scanned
    >once every 10 seconds.  So the center of the instrument should point
    >about 5 degrees away from the direction towards the Earth.  It is possible
    >to imagine that the instrument is 5 degrees off-axis by looking at the
    >pictures carefully.
    Mike, the scenario you propose above implies the axis of rotation of the
    DSP satellite is itself rotating once per day, so as to keep pointing
    to the center of the earth. Using thrusters to this would seem to be
    rather expensive. Can you or others comment on other ways of doing this.
    Tony Beresford
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