TITLE:   GCN CIRCULAR
NUMBER:  28679
SUBJECT: GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
DATE:    20/10/18 10:36:43 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), V. Kim (AFIF, Pulkovo Observatory), A. Pozanenko (IKI), 
E. Klunko (ISTP), M. Krugov (AFIF), N. Pankov (HSE), A. Volnova (IKI) 
report on behalf of IKI GRB FuN:

We observed the filed of GRB 201017A  (Fermi GBM Team, GCN 28665; D'Ai 
et al., GCN 28666; Poolakkil et al., GCN 28675) with AZT-33IK telescope 
of Mondy observatory in R-filter starting on Oct. 17 (UT) 14:56:22 and 
with AZT-20  telescope  of Assy-Turgen observatory starting on Oct. 17 
(UT) 14:15:45  in  r' -filter.  At the edge of enhanced Swift-XRT 
position (Goad et al., GCN 28671) we marginally detected the object 
which is absent in any Pan-STARRS images and PS1 catalog. Position of 
the object is (J2000) 02:26:28.31  +66:40:44.74 with uncertainty of 0.5" 
in each coordinate.

Preliminary photometry of the afterglow candidate  is following

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

2020-10-17 14:15:45  0.2043    r'(AB) 50*60   22.9 0.3   23.2 (AZT-20)
2020-10-17 14:56:22  0.2362    R      30*120  n/d  n/d   21.8 (AZT-33IK)


The photometry is based on the nearby stars of PanSTARRS-PS1 catalog.
RA DEC r
02:26:33.94915 +66:39:38.3372 16.1111
02:26:39.68479 +66:38:36.3089 17.4493