TITLE: GCN CIRCULAR NUMBER: 33383 SUBJECT: GRB 230228A: Mondy optical upper limit DATE: 23/02/28 19:12:56 GMT FROM: XXXX at IKI alex@cgrsmx.iki.rssi.ru
S. Belkin (IKI, HSE), E. Klunko (ISTP), A. Pozanenko (IKI), N. Pankov (HSE) report on behalf of GRB IKI FuN:
We observed the field of GRB 230228A (Dichiara et al., GCN 33378) with AZT-33 telescope of Mondy observatory starting on Feb. 28 (UT) 12:46:56. We do not detect any optical counterpart within the enhanced Swift/XRT error box (Beardmore et al., GCN 33382). Preliminary photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err UL(3sigma)
2023-02-28 12:46:56 0.31053 R 30*120 n/d n/d 21.1
The photometry is based on the nearby USNO-B1.0 stars R2 RA DEC R2 01:13:35.3661600 +44:26:54.711600 15.50 01:13:18.4240800 +44:28:30.280800 16.70
The upper limit is not contradict observations reported earlier (Dichiara et al., GCN 33378; Lim et al., GCN 33380; Lu et al., GCN 33381).