Optical 16 Feb 2007

From: Greg Roberts (grr@telkomsa.net)
Date: Sat Feb 17 2007 - 02:25:08 EST

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    Observations 16 Feb 2007
    Cosatrak 1 (Computerised satellite Tracking System).
    MINTRON low light level CCD surveillance camera (0.005 lux typical
    in non integration mode) and 0.00005 lux in STARLIGHT mode with 128
    frame integration.
    Used with 6 inch F/5 Celestron reflector,integrating for 128 frames
    which is equivalent to an exposure of 2.56 seconds per image.
    Site 0433 : Longitude 18.51294 deg East, Latitude  33.94058 deg S,
    Elevation 10 metres - situated in Pinelands (Cape Town), South Africa
    90013 03 564A   0433 G 20070216191108700 56 15 0806010+130410 39  +080 05
    27168 02 001A   0433 G 20070216193043200 56 15 0722195+070324 39  +095 05
    90054 95 586A   0433 G 20070216193721800 56 15 0310334+034606 39  +115 05
    90055 96 750A   0433 G 20070216194224500 56 15 0718162+111045 39  +120 05
    Stray Seen:
    Ariane 5 debri, range 17710 kms - easy
    28947 06 007C   0433 G 20070216195435800 56 15 0334570+070316 39  +115 05
    (1) Used 6 inch reflector after reducing some of the backlash in the
        mounting but in the end concluded it was not practical to use this
        system on a regular basis. It is impossible to use for LEO satellites
        on account of its very small field of view and , whilst geostationary
        satellites are bright and easy to see, it simply takes too long to
        find each one as the telescope seldom has the object in the field
        of view and I have to scan for it. The backlash in azimuth is of the
        order of about 3 arc minutes - I can live with that - but in elevation
        it is around 20 arc minutes - by inself not much but it is not
        constant. It would appear that the worm shaft has a large wobble-
        the worm shaft is not perfectly straight so the meshing with the
        worm gear ranges from tight to very loose, with subsequent "play"
        or backlash, with the worm/gear contact being rather tight at
        around elevations 20 and 70 degrees. Without scrapping and rebuilding
        the entire elevation drive there is not much that can be done
        mechanically. Then I have the problem that the entire unit is not
        perfectly level - so this introduces a further error in elevation.
        I have been battling with the basic mount for about 40 years and
        trying to level it 100% and never succeeded. The original unit was
        designed for aiming large naval guns and I suspect it was good
        enough for its original purpose but is/was not a precision piece of
        engineering. I will have to go and put on my "thinking" cap
        again - no wonder Im bald! I wonder if the mount wasnt perhaps hit
        by a shell and buckled /warped?
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