TITLE:   GCN CIRCULAR
NUMBER:  33748
SUBJECT: GRB 230506C: SAO RAS optical observations
DATE:    23/05/09 16:04:41 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. Moskvitin, O. Maslennikova (SAO), N. Pankov (HSE, IKI)
and A. Pozanenko (IKI), report on behalf of GRB follow-up team.

We observed the field of GRB 230506C (Tohuvavohu et al., GCN 22731)
with the SAO RAS 1-m telescope Zeiss-1000 + CCD photometer.
The observations started since 1.3528 hours after the trigger
under mediocre weather conditions. We obtained 3 x 300 sec. exposures
in Rc band (May 6, 18:30:29 -- 18:48:26 UT, T_mid - T_0 = 1.5024 h).

The OT (Kuin & Dichiara, GCN 33733; Pankov et al., GCN 33734;
Jelinek et al., GCN 33735; Adami et al., GCN 33741) is marginally
detected in the stacked image with the brightness of R = 20.5 +/- 0.3.
Preliminary photometry is based on R2 magnitudes of nearby USNO-B1
stars. The OT magnitude is not corrected for the Galactic extinction.