Re: Magnitude observations

From: Björn Gimle (b_gimle@algonet.se)
Date: Mon Jul 12 2004 - 10:12:16 EDT

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    I too doubt the need for a new format. The OBSENTRY format
    for IOD is sufficient, and just needs some code addition to allow for
    specular flash computations, as I have requested before.
    
    I also agree with Ted that it would be very useful to include (rough)
    position. It is very convenient to use Ted's ObsReduce program to
    produce the IOD format log.
    
    Using the codes B (H) P (see below) this format could even supply
    the info used in PPAS, and give more info on secondary flashes
    and asymmetric timing of these.
    
    (BTW, I fail to see the reason for keeping an 80-char limit. For
    Windows, Linux, ... users this is quite arbitrary. Even most DOS text
    editors
    support longer lines, and we are talking about forms mode data entry, and
    these programs could be expanded to also allow display/edit of the log file)
    
    The IOD author, George Lewis, says in the help entry for the first
    positional field:
    
    " If all the positional observation fields are complete when the F3 key
      is pressed, the positional observation is output. If, when the F3 key
      is pressed, only some of the positional data fields have been filled
      in, the user is prompted as to whether to proceed. If the answer is
      yes, then none of the positional data fields are output. If the answer
      is no, then the data entry screen is displayed to enable the missing
      fields to be completed. To avoid this prompt when no positional
      observation is to be output, blank out all the positional data fields."
    
    For magnitude data, the following codes exist:
    
    "       Optical Tracking Working Group Codes
    
     E = unusually faint because of eclipse exit/entrance
     F = constant flash period
     I = irregular
     R = regular variations
     S = steady
     X = irregular flash period
    
           Flash Period Codes
    
     B = time zero for averaging several flash cycles
     H = one flash in a series
     P = end time for averaging several flash cycles. Time interval
         from last "B" report divided by flash period reported on
         this line gives number of flashes that occurred since "B".
    
           Miscellaneous Visibility Codes
    
     A = became visible (was invisible); use E for eclipse exit
     D = object in field of view, but not visible
     M = brightest
     N = faintest
     V = best seen using averted vision"
    
    A "fake" (Don Gardner, June 20) Superbird-A obs (note that IOD requires a
    numeric station code SSSS):
    
    NNNNN YY LLLABC SSSS C YYYYMMDDHHMMSSsss tt ce RRRRRRR+DDDDDD pp B+MMm Mm
    SSSsss
    20040 89 041A   9999 G 20040620032906740 17                      P+015 04
    011210
    
    What these numbers mean: http://www.satobs.org/position/IODformat.html
    
    
    Ideally, code M could be used to mark the brightest specular flash, e.g.
    from a flashing near-geosynch satellite, but this is often difficult to
    determine, since these flashes can be near the same brightness for
    many minutes, even hours. It might also mean the peak flash of an
    I, R, X type variation, or even S, meaning the brightest magnitude while
    the satellite range and phase angle varies.
    
    Only one code can be given for each point, so more than one log
    line must be entered to characterize these.
    
    Since a specular flash (or flare) is often 5-10 magnitudes brighter
    than normal maxima, and determination of rotation axis and flash
    cones require a positional accuracy of one degree or better, a
    special code should be assigned for these events. This will also
    simplifiy searching for previous observations of this kind, when
    a sufficient number of observations have been posted to allow the
    spin axis determinations.
    
    Because of the difficulty of determining the brightest specular
    flash over a long interval, separate codes for the first and last
    bright flash observed would be useful.
    
    A separate code for phase-shift of regular flashes would also be useful.
    
    
    ----- Original Message ----- 
    From: "Ted Molczan" <molczan@rogers.com>
    To: "SeeSat-L" <SeeSat-L@satobs.org>
    Sent: Sunday, July 11, 2004 8:06 PM
    Subject: RE: Magnitude observations
    
    
    > Ed, although I am open to the idea of a magnitude-only format, I am far
    from
    > convinced that we really need one.
    >
    > There are a number of significant advantages to combining positional and
    > magnitude observations:
    >
    ...
    
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