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
weather.
Ted Molczan
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