[vsnet-grb-info 17987] SGR 1935+2154: AbAO optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19435
SUBJECT: SGR 1935+2154: AbAO optical upper limit
DATE:    16/05/18 19:43:53 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova  (IKI), R. Inasaridze (AbAO), V. Ayvazian 
(AbAO), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger
GRB follow-up collaboration:

We observed the field of SGR 1935+2154 triggered by Swift (Barthelmy et 
al., GCN 19430; D'Avanzo et al., GCN 19433) and Fermi (Yu et al., GCN 
19434)  with AS-32 (0.7m) telescope of Abastumani Observatory starting 
on May 16 (UT) 23:26:26. We obtained several unfiltered images of the 
field. We do not detect any source within XRT error circle  (D'Avanzo et 
al., GCN 19433).

Preliminary photometry of the field is following

Date       UT start   t-T0     Filter  Exp.    UL (3 sigma)
                      (mid, days)       (s)
                      (after GCN 19430 trig.)

2016-05-16 23:26:26   0.14112  none    29*60  20.4

We also note a variable star in the field in coordinates (J2000) 
19:34:30.09 +21:52:06.2 and R=15.33 +/- 0.04 which coincides with a star 
of USNO-B1.0 1118-0440363,  R2 = 19.38. The star is not related to the 
SGR 1935+2154.

Photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id    R2

1119-0448829    14.61
1119-0448214    16.24
1118-0440633    14.34
1118-0440733    14.93

A finding chart can be found at 
http://grb.rssi.ru/SGR1935+2154/SGR1935+2154_20160516_AbAO.png