Re Milstar 5 video obs

From: Rainer Kracht (R.Kracht@t-online.de)
Date: Mon Mar 03 2003 - 15:59:50 EST

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    On 3 Mar 2003, at 15:57, Rainer Kracht wrote:
    
    > On 3 Mar 2003, at 9:36, Greg Roberts wrote:
    > 
    > 
    > > 
    > > As a matter op operational technique-- when you use the integrated mode
    > > what time do you report -  middle of the exposure? Yesterday I played
    > > with some video recordings I had of satellite passes and integrated the
    > > video frames in software - this does increase sensitivity but of course
    > > my time display in the frames is blurred because of the overlapping of
    > > successive images.
    > Until now I have displayed the avis with virtual dub which gives the
    > elapsed time from the beginning of the file for each frame and have
    > added this time to the start time which is taken from the computer's
    > system clock when the file is created. The system clock is set from
    > a time server.
    > 
    > I have just made a short video of my radio-controlled clock and found
    > that my times are about two seconds late. 
    > I have checked the system clock and found it running two seconds
    > behind the correct time.
    > 
    After I had installed a new program that sets the system clock 
    precisely I have found that the time stamps of the frames are 
    the end times of the integrated frames. So I have to subtract half of
    the integration time to get the middle of the exposure.
    
    I have used 1.28 seconds as the exposure time mostly. So these times
    are all 0.64 seconds late. Fortunately this corresponds to only 10
    arcseconds in position. More severe is the fact that the system clock
    was 2 seconds late today but this is fixed and should not happen
    again...
    
     Rainer
    
    Rainer Kracht
    Elmshorn, Germany
    Station 5005
    53.7695N 9.6626E  9m Potsdam Datum
    53.7679N 9.6614E 47m WGS84
    R.Kracht@t-online.de
    
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