TITLE:   GCN CIRCULAR
NUMBER:  19955
SUBJECT: GRB160927A: D50 optical limit
DATE:    16/09/27 21:09:50 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek, Jan Strobl, Rene Hudec, Vojtech Simon
and Cyril Polasek (ASU CAS Ondrejov, CZ) report:

The 50cm robotic telescope (D50) of Ondrejov
observatory in Czech republic reacted robotically to
the alert of GRB160927A (Gibson et al, GCNC 19952),
obtaining a series of 10s unfiltered images starting at
18:05:29.9UT, i.e. 40s post trigger.

We do not detect any new source within or near the XRT
error circle (Evans, GCNC 19953) in comparison to
USNO-B1.0 catalog neither in single images (3-sigma
limit R>18.7) nor in a combined 25x10s frame (mean exp
time 124s post trigger, 3-sigma limit R>20.5).