Re:Observations 3 Feb 2001

From: Greg Roberts (grr@iafrica.com)
Date: Wed Feb 07 2001 - 01:41:15 PST

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    Hi,
    
    Hope Im not wasting bandwidth and people complain. There has been a
    little saga about my observations of USA 116 on the 3rd Feb with various
    analysts ( - I used a dictionary!) saying one time was out by 2 seconds and 
    others saying it was a different time from the time I had corrected. After 
    playing back the video tape several times- a distinct advantage of the 
    CoSaTrak system where I have hard copy of a satellite pass, I could find 
    NO time error in any of the original times I reported. This now had me 
    worried as my next thought was that my time system was skipping seconds
    which would really be a problem.
    
    However after finding no errors in time I then checked the positions reported
    and I believe I have found my "time error". The observation made at
    22h54m38.58sUT originally had a reported position of RA15h40.99m,
    Dec-38d49.00' - this is INCORRECT - it should be RA15h39.69m,Dec
    -38d40.76'. It just happens that the original reported position lies close to
    the satellite track and was where the satellite would have been about 2 seconds
    earlier! I used SAO stars 206827 and 206887 to define a "finishing line"
    and its easy to see that the original position is some way from this. What I
    suspect happened is that my mouse moved after measuring the correct position
    and I did not notice it and I reported the wrong mouse cursor position.
    
    So it looks like it pays to check each observation carefully, and make sure the
    mouse cursor has not moved ( I must get a better mouse - the one I have is
    pretty putrid anyway - you get what you pay for! )
    
    Best wishes
    Greg 
    
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