Аннотация:MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located
in Argentina was pointed to the Swift possible GRB 180221A (Stamatikos et al GCN 22427)
119 sec after notice time and 257 sec after trigger time at 2018-02-21 06:35:01 UT.
On our first (50s exposure) set we didn't find optical transient within
SWIFT-BAT error-box (RA, Dec 326.772, -72.868, radius 3arcmin).
The 5-sigma upper limit has been about 18.3 mag at single (50 sec) and
19.5 at coadd (310 sec) images.
The message may be cited.
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The observations were made on
zenit distance 73 degrees,
The Sun altitude is -40.6 degree.
Dist. to Moon: 92.17 (Moon coord. 35.522966 d, 8.630816 d)