TITLE:   GCN CIRCULAR
NUMBER:  28673
SUBJECT: GRB 201015A: Assy and Mondy optical observations
DATE:    20/10/17 15:56:12 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 GRB 201015A  (D'Elia et al., GCN 28632) with AZT-33IK 
telescope of Mondy observatory in R-filter starting on Oct. 16 (UT) 
13:42:54 and with AZT-20  telescope  of Assy-Turgen observatory starting 
on Oct. 16 (UT) 14:51:35  in  g',r',i'-filters.  The optical afterglow 
(e.g., Lipunov et al., GCN 28633; Kennea et al., GCN 28635; Malesani et 
al., GCN 28637; Ackley et al., GCN 28639; Hu et al., GCN 28645; Zhu et 
al., GCN 28653) at redshift z=0.426 (de Ugarte Postigo et al., GCN 
28649; Izzo et al., GCN 28661) is detected in stacked images in each filter.

Preliminary photometry of the afterglow is following

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

2020-10-16 13:42:54   0.64075     R      30*120 21.70 0.25  22.0
2020-10-16 14:51:35   0.68081     r'(AB) 36*60  21.85 0.14  23.5
2020-10-16 15:02:53   0.68796     g'(AB) 36*60  22.10 0.10  23.7

The photometry is based on the nearby stars of PanSTARRS-PS1 catalog.
RA, DEC, g, r, i
23:37:17.49934 +53:24:05.6357 18.6327 17.7832 17.4125
23:37:21.06032 +53:24:57.1308 19.4472 18.4947 18.0340