Re: Almost time for flaring GEOSATS

From: Cees Bassa (c.g.bassa@phys.uu.nl)
Date: Fri Mar 02 2001 - 12:21:42 PST

  • Next message: Alan Pickup: "Decay watch: 2001 Mar 2"

    >Last year Rainer Kresken posted info on seeing GEOSATS flaring just prior
    >to Earth shadow entry. The dates as a function of latitude are below and 
    >we are approaching that time for the northern hemisphere.
    >
    >latitude    optimum date (Day/month)
    >-80          01/09
    >-60          04/09
    >-40          09/09
    >-20          15/09
    >0            23/09
    >+20          30/09
    >+40          07/10
    >+60          12/10
    >+80          15/10
    
    I've tried to compute these days for myself but I got different results. 
    When I calculated the
    day for, say a latitude of +40, I found September 9 instead of October 7, 
    the result belonging
    to the latitude with the other sign.
    
    After some thinking I found out why: I assumed that the solar panels of the 
    satellites track the
    sun, but I guess Rainer Kresken assumed they didn't. This explains why the 
    dates belonging to
    the latitudes get swapped. A simple correction was made in my program so 
    that it does give the
    right results.
    
    Now I'm wondering if all geostationary satellites keep their solar panels 
    fixed, i.e. they don't track
    the sun. It seems very plausible, but I can imagine that it is a little 
    effort to let the panels track the sun. Are there any geosats with solar 
    panels that do track the sun?
    
    Here is my list for the March 20, 2001 Equinox, with and without tracking 
    solar panels:
    
                  Without        With Tracking
    Latitude   Month/Day Month/Day
      80.0000    2 26        4 12
      60.0000    2 28        4 10
      40.0000    3  5        4   6
      20.0000    3 12        3 29
        0.0000    3 21       3 21
    -20.0000    3 29        3 12
    -40.0000    4  6        3   5
    -60.0000    4 10        2 28
    -80.0000    4 12        2 26
    
    So for me here at latitude +52 the optimum for non-tracking satellites has 
    just passed, and
    clouds are keeping me inside for way too long now.
    
    Regards,
             Cees Bassa
    
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