Re: One flare seen twice, 830 miles apart

From: Björn Gimle (bg_26934@glocalnet.net)
Date: Fri Nov 24 2006 - 03:37:26 EST

  • Next message: Marco Langbroek: "Obs ML (4353), 24 Nov 2006: Lacrosse 3 & 5 Rk, ISS"

    You can use Rob's IridFlar. Click N on the main menu
    ( N  Number of output lines per flare: ) so it shows 3.
    (and check start time + duration!)
    Here is 'Brief' output, yet edited to fit in mail one-liners:
    
          Local    Local   Iridium   Flare  Maximum Flare  Ir
    Day   Date     Time    Azm El  Ang Mg  Latit.  Longit.  # S
    -----------------------------------------------------------
    Wed  6-11-22 18:32:22  161 39  3.1  2  43.438  -92.543 13
    Wed  6-11-22 18:32:39  163 34  0.1 -7  42.467  -92.403 13
    Wed  6-11-22 18:32:59  165 30  2.8  2  41.432  -92.261 13
    
    You may also want to increase the
    'Maximum off-specular angle' from 5 to 15
    (and Magnitude of dimmest nighttime flare)
    and change observer location
    to get a wider spread of points.
    Using magnitude 6 and a rough extrapolation to
    latitude 36N, longitude 91.5W, it gives:
    
    Wed  6-11-22 18:33:40  160 48  6  R  39.205  -91.970 13
    Wed  6-11-22 18:34:38  167 32 -5  R  35.990  -91.587 13
    Wed  6-11-22 18:36:00  171 19  6  R  31.552  -91.111 13
    
    FWIW, using mag 7.7 lat 39.2 long -91.8 I can get
    Wed  6-11-22 18:32:40  157 50  6  R  42.463  -92.403 13
    Wed  6-11-22 18:33:39  166 33 -3  R  39.179  -91.967 13
    Wed  6-11-22 18:36:20  172 11  8  R  30.452  -91.001 13
    and
    Mon  6-11-27 18:11:30  173 51  6  R  42.825  -92.268 52
    Mon  6-11-27 18:12:34  175 33 -7  R  39.197  -91.821 52
    Mon  6-11-27 18:15:00  177 12  8  R  30.845  -90.989 52
    
    
    ----- Original Message -----
    From: "Tom Wagner"
    ...
    > across a large distance. To determine where a specific flare would go
    after
    > it passed my place (moving south in the case) I used Heavens-Above and
    > Google Earth. The ground track was positioned through the Midwest US. The
    > flare I was interested in would occur off iridium 13 at 18:32:40 my local
    > time on Nov 22, 2006. The ground track for the satellite itself and the
    > light beam are not in the same place (obviously) and are not parallel (at
    > least at this time), I discovered. My technique was crude but it worked.
    [I
    > would appreciate input as to a service that provides the flare ground
    track
    > ready made.]
    ...
    ****I have a question; will the same flare that occurs for me occur for
    Baton Rouge off and on in the future?  I am thinking that because of the
    inclination of the orbital plane and our coordinates on the Earth that this
    will occur regularly.
    
    Yes, and no! It also depends on the Sun's declination, and if an orbital
    plane happens to be in the same relative position.
    But it will approximately repeat for a week or more.
    
    /Björn
    
    
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