Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 33608

GRB 230409B: Mondy optical upper limit
2023-04-12T23:21:33Z (a year ago)
Alexei Pozanenko at IKI, Moscow <>
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.
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 
Looking for U.S. government information and services? Visit