Re: BY PPAS Apr 20

From: Bjoern Gimle@GlocalNet (Gimle@GlocalNet)
Date: Mon Apr 21 2008 - 07:07:45 UTC

  • Next message: Bjoern Gimle@GlocalNet: "Re(2): BY PPAS Apr 20"

    Of course the convention is not to count EVERY OTHER flash, though this 
    comes close to reality for cylindrical bodies.
    
    We should analyze the repeating patterns, and REPORT the time between 
    CORRESPONDING flashes, and the number of complete cycles observed.
    To avoid reporting an non-integer number of cycles, some understanding of 
    the pattern is necessary. Even your "EO" flashes may turn out to be 
    asymmetric (in time) - sometimes a slight displacement due to synodic 
    effects, sometimes from slightly non-cylindrical, in some cases even 1/3 or 
    1/4 period or seemingly arbitrary, due to satellite geometry.
    
    To visualize the flash pattern (unless you have a photometric recorder) my 
    SYNODIC.EXE or an equivalent spreadsheet should be used.
    This compares observed (cumulative) flash timings to multiples of the 
    assumed period, which makes it easy to detect the pattern, and possible 
    erroneous keypresses.
    Using cumulative instead of lap times "removes" the risk of a single 
    transcription error biasing the entire series, and resulting period 
    computed.
    Determining the period from ALL measured times, rather than last-first, 
    reduces the the standard error (from accuracy/# of cycles), possibly by a 
    factor of 1/sqrt(# of points),
    and the risk of having a transcription error on the first or last 
    measurement deteriorate the reported period.
    
    Please send me some complete measurement series, and I will show you a few 
    samples.
    
    /Björn
    
    ----- Original Message ----- 
    
    Note 1: Started as eO (even flash dim, odd bright) then evolved to EO around 
    #60, then by #90 was Eo with brightest (-1 mag) flashes around #120, but I 
    have counted only every other flash as this seems to be the convention.
    
    
    
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