USA 193 visibility windows

From: Ted Molczan (
Date: Tue Feb 12 2008 - 03:00:46 UTC

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    Below are estimated visibility windows of USA 193 (aka 06057A / 29651) for the
    latitudes of the positional observers known to me.
    A visibility window is a period of time during which a satellite is visible in
    an observer's morning or evening twilight sky.
          Period      Lat    Time  Dir
    Feb 05 - Feb 11  44 N  Morning  SB
    Feb 07 - Feb 13  30 N  Morning  SB
    Feb 13 - Feb 18  30 N  Evening  NB
    Feb 16 - Feb 22  44 N  Evening  NB
    Feb 17 - Feb 29  51 N  Evening  NB
    Feb 18 - Mar 02  56 N  Evening  NB
    Feb 20 - Feb 27  35 S  Morning  SB
    Mar 03 - Mar 07  56 N  Evening  SB
    Mar 01 - Mar 08  51 N  Evening  SB
    Mar 04 - Mar 10  44 N  Evening  SB
    Mar 08 - Mar 11  30 N  Evening  SB
    Mar 14 - Mar 17  35 S  Morning  NB 
    SB and NB denote southbound and northbound passes, respectively.
    Not all observers near a given latitude will have good passes on each day of a
    window. A few will have passes culminating high above the horizon, most will
    have much lower elevation passes.
    I am near latitude 44 N, so my morning south-bound window ended today. The same
    window closes about Feb 13 for observers near 30 N, for whom an evening
    northbound window opens about the same day. That window will move progressively
    northward, opening for observers at 44 N on Feb 16.
    Collectively, observers at or north of 44 N will have evening visibility until
    about March 10.
    During the final few days before decay, currently estimated to occur within
    about one week of March 18, observers near 35 S will have morning visibility.
    Since there are few positional observers in the southern hemisphere, we are
    likely to lose the object after about March 10, unless they are interested to
    observe it, and fortunate to have reasonably high-elevation passes and good
    Ted Molczan
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