TITLE:   GCN CIRCULAR
NUMBER:  22497
SUBJECT: GRB 180314B: Zeiss-1000/CrAO optical upper limit
DATE:    18/03/15 17:48:37 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI),  A. Novichonok (KIAM, PetrSU),  I. 
Nikolenko (CrAO), A. Volnova (IKI), I. Molotov (KIAM) report on behalf 
of larger GRB follow-up collaboration:

We observed the field of  Swift GRB 180314B (D'Avanzo et al., GCN 22491) 
with Zeiss-1000/Koshka (CrAO) telescope starting March 15 (UT) 01:55:39.
We obtained several  images in R-filter. We do not detect any source 
within enhanced Swift-XRT position (Beardmore et al., GCN 22494). 
Preliminary photometry of the field is following.

Date        UT start  t-T0      Filter Exp.   OT    Err.  UL
                       (mid, days)    (s)

2018-03-15  01:55:39  0.15459    R     7*180  n/d   n/d   22.2

The photometry is based on nearby USNO-B1.0 stars

USNO-B1_id   R1
1135-0426232 15.02
1135-0426125 15.64
1136-0433074 16.46