TITLE:   GCN CIRCULAR
NUMBER:  28871
SUBJECT: GRB 201104B: continued TSHAO optical observation
DATE:    20/11/09 12:57:32 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Kusakin (FAP), N. Pankov (HSE), I. Reva (FAP), A. 
Pozanenko (IKI) report on behalf of GRB-IKI-FuN:

We continued observations of the  GRB 201104B (Sbarufatti et al., GCN 
28825) with Zeiss-1000 1-m telescope of Tien Shan Astronomical 
Observatory starting on Nov. 06 (UT) 15:04:58.

The optical afterglow (Marshall et al., GCN 28827; Vielfaure  et al., 
GCN 28840; Oates  et al., GCN 28851; Belkin et al., GCNs 28852, 28856; 
Gupta et al., GCN 28860; Hosokawa et al., GCN 28870) at redshift z = 
1.954 (Vielfaure et al., GCN 28840) is detected in stacked image in 
R-filter. Preliminary photometry of the afterglow is following.

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

2020-11-06 15:04:58 1.92271  R      50*90 22.20 0.21 22.4

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

USNO-B1.0_id R2
0979-0003163 17.51
0979-0003223 17.47