Аннотация:MASTER-SAAO robotic telescope (Global MASTER-Net http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, v.2010, 30L)
was pointed to Swift Trigger 887541 (Barthelmy et al. GCN23849,Ttrig=2019-02-03 21:18:17UT)
~3h after trigger time (at alert time error-box was under the horizon at all MASTER observatories)
at 2019-02-04 00:16:44UT.
There is no OT inside Swift-XRT error-box with unfiltered mlim=17.5
(5sigma, 180s exposition)
The observations started when error-box altitude was 9 deg.
The sun altitude was -38deg.
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