TITLE:   GCN CIRCULAR
NUMBER:  22577
SUBJECT: GRB 180331B: AbAO optical observations
DATE:    18/04/01 03:30:42 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of GRB 180331B  (Lien  et al., GCN 22573) with 
AS-32 (0.7m) telescope of Abastumani Observatory starting on Mar. 31 
(UT) 17:49:41.   We do not detect any object within enhanced XRT 
position (Goad et al., GCN 22575). Preliminary photometry of the field 
is following.

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

2018-03-31  17:49:41   0.11370   CR     38*60  n/d   n/d  22.3

The photometry is based on nearby USNO-B1.0 stars (R2 magnitude).