Re Milstar 5 video obs

From: Rainer Kracht (
Date: Mon Mar 03 2003 - 09:57:53 EST

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    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.
    > Do you make use of a dark frame or flat field to remove image defects etc?
    I have worked with Giotto, a program that will add all frames of an
    avi-file into a single image. It does subtract a dark frame from each
    avi frame if you specify one.
    Usually I take a 13 second avi with the closed lens cap, then add the
    frames with giotto and save the result as the current dark frame.
    To subtract a dark frame from an avi I think I have to split the avi
    into bmps then subtract the dark frame from each bmp and reassemble
    the processed bmps into an avi. I have not done this until now.
    Rainer Kracht
    Elmshorn, Germany
    Station 5005
    53.7695N 9.6626E  9m Potsdam Datum
    53.7679N 9.6614E 47m WGS84
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