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GCN Circular 31844

GRB 220403B: Mondy optical upper limit
2022-04-06T16:37:01Z (2 years ago)
Alexei Pozanenko at IKI, Moscow <>
N. Pankov (HSE),  A. Pozanenko (IKI),  E. Klunko (ISTP), S. Belkin (IKI) 
  report on behalf of GRB IKI FuN:

We observed the field of  GRB 220403B  (Klingler  et al., GCN 31820) 
with AZT-33 telescope of Mondy observatory starting on April, 05  (UT) 
15:00:54.   We do not detect the optical afterglow (Klingler  et al., 
GCN  31820; Jelinek  et al., GCN 31821; Zhu  et al., GCN 31823; Rossi 
et al., GCN 31826; Pankov et al., GCN 31837; Hu et al., GCN 31841; see 
also early upper limits in Lipunov et al., GCN 31825; Grossan  et al., 
GCN 31830) in the combined image.
Preliminary photometry of the  combined image is following

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

2022-04-05  15:00:54 1.77723   20*120  R      n/d    n/d    23.2

The photometry is based on nearby USNO-B1.0 stars, R2 magnitude
USNO-B1.0_id R2
1791-0003982 16.77
1791-0003984 17.83
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