Re: Satellite Elements from Astrometric Observation.

From: Marco Langbroek (
Date: Sat Mar 28 2009 - 14:49:45 UTC

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    Hi Bev,
    The task consists of obtaining plate coefficients for either stars or star 
    trails; and determining coordinates relative to the obtained plate solution for 
    an object (satellite), which will be either a point or a trail.
    The problem is (and here's the difference with e.g. asteroids) that one or both 
    of both categories (satellite or stars) will be trails usually. Would this not 
    be the case, i.e. would it concern point sources only, then regular astrometry 
    software like Astrometrica or several of the other available astrometry software 
    suites would do well.
    For LEO objects the satellite will always be a trail. Stars might be point 
    sources if guided, but personally I work unguided as the equipment in my case 
    consists simply of a DSLR on camera tripod.
    For GEO sats either the satellite will be a point and the stars trailed 
    (unguided CCD): or the satellite a trail and the stars points (guided CCD). 
    Usually it will be the first option as this allows fainter satellites to be 
    Other HEO objects (e.g. Molniya's) will always be trails, and depending on the 
    method the stars will be trails or points, like LEO objects.
    Also note that usually the original file format will not be FITS, as most camera 
    observers use a video camera or in my case a DSLR. Only for GEO sats some use CCD.
    - Marco
    Ted Molczan schreef:
    > I am forwarding this message to the list.
    > Ted Molczan
    > -----Original Message-----
    > From: Bev M Ewen-Smith [bmes at] 
    > Sent: March 27, 2009 3:21 PM
    > To:
    > Subject: Re: Satellite Elements from Astrometric Observation.
    > Hi,
    > I am new to this application, but is this just a matter of 
    > calibrating the plate coefficients of an image using, say GSC start 
    > positions, and then making astrometric measurements of a specific 
    > object/point in the image, that is required?   If so, my FitsX (not 
    > very recent) program does that.
    > I probably shouldn't say so, but the plate calibration process is 
    > done even more cleverly by Alfonso Pulido's Elbrus 
    > ( which works 
    > out what you are looking at, without even needing to tell it where in 
    > the sky it is.
    > Regards
    > Bev
    > COAA
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