TITLE:   GCN CIRCULAR
NUMBER:  23390
SUBJECT: GRB 181030A: SAO RAS optical observations
DATE:    18/10/30 03:51:54 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of larger collaboration.

We observed the field of GRB 181030A (Sonbas et al., GCNC #23389)
with the Zeiss-1000 telescope of SAO RAS (+ CCD photometer)
on the October, 30.

The observations started since 10 minutes after the trigger
(UT_start = 01:37:35, UT_end = 02:49:36).
We obtained 12 x 300 sec. images in Rc band. We detect the OT
discovered by the Swift/UVOT at the position (+/- 1"):

R. A. (2000) =  09:47:42.3
Decl. (2000) = +14:39:25.8

The OT magnitude is R = 19.12 +/- 0.03 (UT_mid = 02:13:35).

Calibrations were made against the nearby SDSS stars
(magnitudes transformed to Rc according to the Lupton, 2005).