GCN Circular 33608

Subject

GRB 230409B: Mondy optical upper limit

Date

2023-04-12T23:21:33Z (8 months ago)

From

Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

S. Belkin (IKI), E. Klunko (ISTP), A. Pozanenko (IKI), N. Pankov (HSE) 
report on behalf of GRB IKI FuN:

We observed the field of Swift GRB 230409B (Beardmore et al., GCN 33592) 
with AZT-33IK telescope of Mondy observatory in R-filter on 2023-04-09 
starting (UT) 14:52:05. We do not detect the optical counterpart (Kuin 
et al., GCN 33595) within the enhanced Swift/XRT error box (Evans et 
al., GCN 33594). Preliminary photometry of a stacked image is following

Date       UT start  t-T0     Exp.  Filter   OT   Err.  UL(3sigma)
                     (mid, days)  (s)

2023-04-09  14:52:05 0.42231  26*60 R        n/d  n/d   20.5

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0
RA DEC R2
21:58:01.9195200 +52:49:21.982800 15.15
21:58:13.7054400 +52:48:57.002400 15.56
21:57:54.5028000 +52:50:57.080400 15.95

The upper limit does not contradict result reported by Adami et al. (GCN 
33607).