TITLE:   GCN CIRCULAR
NUMBER:  23302
SUBJECT: GRB 180930A: TSHAO optical upper limit
DATE:    18/10/03 17:10:51 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Kusakin (FAPHI), A. Pozanenko (IKI), I. Reva 
(FAPHI),  A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 180930A (Tohuvavohu et al., GCN  23279) 
with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory 
starting on September 30 (UT) 21:55:14, obtaining a total of 31*120 s 
exposure in the Rc-band. Within enhanced XRT position (Osborne et al., 
GCN 23282)  we do not detect any object. Preliminary photometry of the 
field is following.

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

2018-09-30 21:55:14 0.41030 R      31*120 n/d   n/d 20.1

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