TITLE:   GCN CIRCULAR
NUMBER:  27830
SUBJECT: GRB 200524A: Assy optical observations
DATE:    20/05/27 15:13:26 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), V. Kim (AFIF, Pulkovo Observatory), A. Pozanenko (IKI), 
M. Krugov (AFIF),  E. Mazaeva  (IKI),  A. Volnova (IKI)  report on 
behalf of larger GRB IKI FuN collaboration:

We observed Fermi-LAT  GRB 200524A (Dirirsa et al., GCN 27797; see also 
Pookalil et al., GCN 27809; Capalbi  et al., GCN 27811; Gupta et al., 
GCN 27818) with AZT-20 1.5 m telescope  of Assy-Turgen observatory 
starting on May. 26 (UT) 15:34:49  in  r'-filter. Optical afterglow 
discovered by ZTF (Ho et al., GCN 27799) and observed by several 
observations (Kumar et al., GCN 27800; Rumyantsev et al., GCN 27802; 
Sanwal et al., GCN 27803; Perley et al., GCN 27805; Kumar et al., GCN 
27806; de Ugarte Postigo et al., GCN 27807; Blazek et al., GCN 27810; 
Ogawa et al., GCN 27813; Izzo, GCN 27817; Belkin et al., GCN 27820; Kuin 
et al., GCN 27825). Preliminary photometry of the afterglow is following

Photometry of the field is following.

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

2020-05-26 15:34:49   2.4721     r'(AB) 98*60  22.57 0.10  24.4

The photometry is based on the nearby stars of PS1 catalog.
PanSTARRS-PS1_id   r
181072130294808209 20.4066
181072130171186332 20.9877
181082129951473104 20.1196