TITLE:   GCN CIRCULAR
NUMBER:  29181
SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
DATE:    20/12/28 00:05:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), O. Burhonov (UBAI), R. Ya. 
Inasaridze (AbAO), P. Levkina (INASAN), N. Pankov (HSE, IKI), A. Volnova 
(IKI), Sh. Ehgamberdiev (UBAI)  report on behalf of GRB IKI FuN:

We finished observations of the ZTF20acozryr/AT2020yxz (Coughlin et al., 
GCN  28841)  with AZT-22 telescope of Maidanak observatory, AS-32 
telescope of Abastumani observatory, and Zeiss-2000 telescope of Terskol 
observatory.  The optical transient (Coughlin et al., GCN  28841; Xu  et 
al., GCN 28846; Zhu et al., GCN 28854; Mao et al., GCN  28861; Belkin et 
al., GCNs 28862, 28875, 28883, 28886;  Mao et al., GCN 28863; Kumar et 
al., GCN 28876; Paek  et al., GCN 28880; Moskvitin et al., GCN 28926) at 
redshift  z = 1.105 (Xu et al., GCN 28847) associated with afterglow of 
GRB 201103B (Ursi et al., GCN 28831; Svinkin et al., GCN 28844; Evans et 
al., GCN 28858).

The photometry reported early in Volnova  et al., GCN 28925 must 
corrected the GCN 28886. We apologize for inconvenience and thank to 
D.A. Kann who pointed out for typo in the GCN 28925.
We repeat corrected photometry of our CrAO/ZTSh optical observation on 
2020-11-13 22:58:04 below. We also add photometry of positive detections 
and meaningful upper limit. the photometry below is still preliminary. 
The photometry is based on the same reference stars of USNO-B1.0 stars.

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

2020-11-12 20:20:48  9.12087    R  80*60   21.70 0.35   21.7 AS-32
2020-11-13 22:58:04 10.21897    R  24*120  22.45 0.14   23.6 ZTSh
2020-11-23 19:29:37 12.07213    R  14*180  22.80 0.13   24.1 AZT-22
2020-11-23 19:26:37 20.08671    R  30*180  n/d   n/d    23.2 AZT-22

A full light curve and upper limits obtained in our observations 
(R-filter) can be found in

http://grb.rssi.ru/GRB201103B/GRB201103B_LC_R.png

A typical power law  light curve (index of ~1.12) can be suggested based 
on our observations and photometry gathered from  GCNs, see

http://grb.rssi.ru/GRB201103B/GRB201103B_LC_GCN.png

One can suggest overlay bumps (or plateau) on  the light curve of at 2-3 
days, and 5-9 days after burst trigger.

If we extrapolate the power law curve backward to the 200 seconds the 
afterglow brightness could have ~12m. If so, one can look for data in 
all sky cameras or wide field surveys to search early phase of the 
afterglow of the GRB 201103B (trigger time (UT) 2020-11-03 18:06:45.36, 
Ursi et al., GCN 28831).