TITLE:   GCN CIRCULAR
NUMBER:  28505
SUBJECT: GRB 200922A: Chilescope optical observations
DATE:    20/09/26 16:18:20 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), S. Belkin (IKI), A. Volnova (IKI), P. Minaev (IKI), 
N. Pankov (HSE)  report on behalf GRB IKI FuN collaboration:

We observed the field of GRB 200922A (Moss et al., GCN 28471) with 
RC-1000 Chilescope observatory  in r'-filter starting on 2020-09-22 (UT) 
23:25:05. In a single obtained image of 1200 s exposure we cannot 
resolve the OT reported earlier (Moss et al., GCN 28471; Izzo et al., 
GCN 28478; Siegel  et al., GCN 28482; Malesani et al., GCN 28492). 
Instead we subtract the flux of nearby star from SkyMapper DR1.1 from 
the (nearby star + OT) photometry.
Preliminary photometry of the OT after the above-mentioned procedure is 
following.

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

2020-09-22 23:25:05  0.478   r'     1200  18.92  0.05  20.7

The photometry is based on nearby SkyMapper DR1.1  stars.