[vsnet-grb-info 27199] GRB 210112A: Mondy optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29302
SUBJECT: GRB 210112A: Mondy optical observations
DATE:    21/01/13 20:28:18 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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 210112A (Ambrosi  et al., GCN 29289; Ursi 
et al., GCN #9293) with AZT-33IK telescope of Sayan observatory (Mondy) 
starting on 2021-01-12 (UT) 20:41:40. The optical afterglow (Ambrosi  et 
al., GCN 29289; Kann  et al., GCNs 29296, 29300) is not detected in 
stacked  image in R-filter. The non detection of the afterlow is 
consistent with other non-detections in R-filter (Novichonok  et al., 
GCN 29292; Gupta et al., GCN 29301).

Preliminary photometry of the optical transient in a combined image is 
following

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

2021-01-12 20:41:40   0.80738    R      18*120   n/d  n/d   22.4


The photometry is based on the nearby USNO-B1.0 stars.