RE: Optical 20 Dec 2012

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Fri Dec 21 2012 - 14:42:58 UTC

  • Next message: Ted Molczan: "RE: Optical 20 Dec 2012"

    Kevin Fetter responded to Greg Roberts:
    
    > --- On Fri, 12/21/12, Greg Roberts <grr@telkomsa.net> wrote:
    > 
    > UNKNOWN SEEN:
    > ---------------
    > 88888 12 854A   0433 G 20121220184654740 55 15 0415413+244919 19  +050 05
    > 88888 12 854A   0433 G 20121220184657740 55 15 0414136+252615 19  +050 05
    > 
    > UNID
    > 1 99999           12355.78261273 0.00000237  00000-0  50000-4 0    02
    > 2 99999  98.7779  32.6361 0007144 274.2656  61.2462 14.59474373    06
    > 
    > My dumb question of the day, could this sat in a 98 degree orbit, be a essaim sat. Been
    > awhile since they have been observed.
    
    It's the kind of dumb question I like. I have yet to analyze Greg's UNID, but if I cannot match it to anything else, I
    will consider the Essaim satellites. It is a little known fact that they were decommissioned into faster decaying orbits
    in late 2010. I do not have the details at hand, but some time ago, I produced this estimate for an arbitrary date and
    argument of perigee:
    
    Essaim 1 estimate                                        407 X 660 km
    1 70000U          10274.00000000  .00000000  00000-0  00000-0 0    04
    2 70000  98.2800 244.9744 0183000 201.0718  49.7537 15.10000000    03
    
    It propagates to within about 10 deg of RAAN of the circular orbit you fit to Greg's observations, which is sufficiently
    close to be interesting - especially if better candidates (none come to mind immediately) can be excluded.
    
    Next step is to try to fit my orbit to Greg's observations. Almost any orbit can be made to fit because the time span is
    short, but we can reasonably start by fixing my values of inclination, eccentricity and mean motion, and allowing the
    others to vary. With some effort a reasonable recovery TLE may emerge.
    
    I am pressed for time at the moment, so not certain when I will have anything more to report. Soon, I hope.
    
    Ted Molczan
    
    
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