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GCN Circular 31018

GRB 211023A: continued Mondy optical observations
2021-10-28T13:05:00Z (3 years ago)
Alexei Pozanenko at IKI, Moscow <>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), 
  report  on behalf of GRB IKI FuN:

We observed the GRB 211023A (Fermi GBM team, GCN  30958) with AZT-33IK 
telescope of Sayan observatory (Mondy)  starting on 2021-10-26  (UT) 
14:47:57.  We obtained 17 images in R-filter. The afterglow   of the GRB 
211023A (Lipunov   et al., GCN  30977;  Kann  et al. GCN 30982; Hu et 
al. GCN 30990; Belkin et al., GCN 31004) is clearly detected. 
Preliminary photometry of the afterglow in a stacked image is following

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

2021-10-26 14:47:57  3.09182    R      30*120  20.57 0.06  22.7

The photometry is based on the nearby USNO-B1.0 stars
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75
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