TITLE:   GCN CIRCULAR
NUMBER:  22223
SUBJECT: GRB 171205A: SAO-RAS optical observations
DATE:    17/12/10 10:02:37 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova (IKI), A. Moskvitin (SAO RAS), A. Pozanenko (IKI) report on 
behalf of of larger GRB follow-up collaboration:

We observed the field of GRB 171205A (D'Elia et al., GCN 22177)   with 
Zeiss-1000  telescope of SAO-RAS Observatory starting on Dec. 09 (UT) 
01:07:09. We took several images in R-filter.  The afterglow of GRB 
171205A (Izzo et al. GCN 22180; Emery et al. GCN 22181; Butler et al. 
GCN 22182; Mao et al. GCN 22186; Choi et al. GCN 22188; Melandri et al. 
GCN 22189; Steeghs et al. GCN 22190; Cobb et al. GCN 22192; Volnova et 
al. GCN 22193; Guidorzi et al. GCN 22197; Schmidl et al. GCN 22198; 
Lipunov et al. GCN 22199;  Ugarte Postigo et al. GCN 22204)  is clearly 
detected. Preliminary photometry is following.

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

2017-12-09  01:07:09 3.79078  R      22*300  18.60  0.04  22.5

The photometry is based on several nearby USNO-B1.0 stars previously 
used in GCN 22193.