Optical 04 Jan 2010-Part 2

From: Greg Roberts (grr@telkomsa.net)
Date: Wed Jan 06 2010 - 08:28:33 UTC

  • Next message: Gordon Prichard: "Re: Cataloging the 1000's"

     Observations 04 Jan 2010
     --------------------------------
     
     Cosatrak 1 (Computerised satellite Tracking System).
    Camera mount now carries two systems that can be operated
    together as two totally different sytems and computers used.
    Generally the DSI Pro II camera will be used for high altitude
    slow moving objects. Tests indicate that its sensitivity
    is better than the MINTRON  but as its not possible (?) to time
    stamp to better than 1 second accuracy the time resolution is not
    good enough for LEO objects.
     
     Meade DSI Pro II Monochrome CCD camera without filters.
    using integration times of 2 to 5 seconds depending on brightness
    of sky in particular area.No image processing done.
     
     Used with 4 inch SKYWATCHER refractor- model 1025 - fitted with home
    made focal reducur to give an f/2.56 system. Image scale is 6.56 arc
    sec/pixel and field of view 84.8 x 63.2 arc minutes. This telescope
    will replace the 6 inch reflector used previously as image quality is
    better, has a larger field of view, less surface area so less prone to
    wind shake. Shows 15th magnitude stars in real time with reasonably
    good conditions.
     
     Exposure time to nearest second inserted into image FITS header
    from PC clock which is frequently checked against GPS signal.
     
     Site 0433 : Longitude 18.51294 deg East, Latitude -33.94058 deg,
    Elevation 10 metres-situated in Pinelands (Cape Town),South Africa
     
     FOR CLASSFD.TLE:
     =================
     
     21775 91 076A   0433 F 20100104192548000 56 15 2129370-311102 39  +115 05
    21775 91 076A   0433 F 20100104192645000 56 15 2127260-344813 39  +112 05
    21775 91 076A   0433 F 20100104192729000 56 15 2125100-374528 39  +110 05
    21775 91 076A   0433 F 20100104192800000 56 15 2123130-395912 39  +110 05
    21775 91 076A   0433 F 20100104192822000 56 15 2121410-412928 39  +110 05
    21775 91 076A   0433 F 20100104192850000 56 15 2119190-433354 39  +110 05
    21775 91 076A   0433 F 20100104193055000 56 15 2103220-531237 39  +110 05
    21775 91 076A   0433 F 20100104193207000 56 15 2047390-585804 39  +115 05
    21775 91 076A   0433 F 20100104193228000 56 15 2041363-603834 39  +115 05
    21775 91 076A   0433 F 20100104193247000 56 15 2035150-621120 39  +120 05
    90020 04 539A   0433 F 20100104191217000 56 15 1208010-653454 39  +105 05
    90020 04 539A   0433 F 20100104191300000 56 15 1143350-630013 39  +105 05
    90020 04 539A   0433 F 20100104191334000 56 15 1128140-605337 39  +105 05
    90020 04 539A   0433 F 20100104191415000 56 15 1113050-581700 39  +105 05
    90020 04 539A   0433 F 20100104191516000 56 15 1056020-542725 39  +105 05
    90020 04 539A   0433 F 20100104191550000 56 15 1048260-522028 39  +105 05
    90020 04 539A   0433 F 20100104191704000 56 15 1036030-480335 39  +110 05
    90020 04 539A   0433 F 20100104191808000 56 15 1028090-443413 39  +115 05
     
     Notes:
     --------
     
     (1) These objects are not really CCD objects as time resolution better
     than about 1 second needed on account of their angular velocity.
     However these two objects were rather faint - around 10-11th magnitude
     and rather low elevation so too faint to track with the video system which
     has 0.1 sec time resolution. In the above cases the mount was
     automatically tracking on the satellite with exposures of about 2-3
     seconds so the satellite image is integrated whilst stars are trailed.
     Whenever a suitable star configuration encountered I manually capture
     the image which is then subsequently measured .
     
     However there will be some time jitter as the FITS image only captures
    to the nearest second. Also there is probably some time latency in that
    the image actually has a time "delay" or offset from the PC time.
    Consequently I would expect a "jitter" of around a second (or maybe even
    two seconds) on the "observed" time. The geometry will be correct but
    there will be time "jitter".
     
     So the above observations to be used with care, but my view is that an
    accurate position with small time jitter is better than no observation
    at all, especially when the objects are not that easy or frequently
    observed.
     
     
     (2) The observations made with the video system will be reported a little
    later today - assuming no interruptions :-))
     
     Cheers
     Greg 
     
     
    
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