[vsnet-grb-info 26777] ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28880
SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
DATE:    20/11/11 11:54:49 GMT
FROM:    Gregory SungHak Paek at SNU  <shpaek at astro.snu.ac.kr>

Gregory S.H. Paek (SNU), Myungshin Im (SNU), Joonho Kim (SNU), Gu Lim
(SNU), Mankeun Jeong (SNU), Chung-Uk Lee (KASI), Seung-Lee Kim (KASI),
Hyun-Il Sung (KASI),  Taewoo Kim (DOAO), and Wonseok Kang (DOAO) and GECKO
team

 We observed the ZTF20acozryr/AT2020yxz (Coughlin et al., GCN 28841) in
BVRI with various optical telescopes of the GW EM-Counterpart Korean
Observatory (GECKO). The facilities used for the observations are the 1.6-m
class telescopes of Korea Microlensing Telescope Network (KMTNet) located
in Siding Spring Observatory (SSO) and South African Astronomical
Observatory (SAAO), the 1-m telescope in Deokheung Optical Astronomy
Observatory (DOAO), the 1-m telescope the Mt. Lemmon Optical Astronomy
Observatory (LOAO), and the 0.36-m KIAS Chamnun Telescope (KCT) and RASA36
telescope in Chile. We calibrated flux with PS1 and APASS catalog, and the
magnitudes are in AB system. The magnitudes are not corrected for galactic
extinction. Preliminary R-band magnitudes are given for the most recent a
few epoch observations.

Obs.&Tel.           DATE-OBS(UT)    Filter   Mag    Error  t-t0(days since
burst)
----------- ----------------------- ------ ------- -------
----------------------
DOAO        2020-11-08T19:51:31     R      21.6    0.1     5.07
KCT         2020-11-10T04:27:38     R      21.8    0.3     6.43
KMTNet-SAAO 2020-11-10T21:37:55     R      21.8    0.1     7.1

t0 = 2020-11-03T18:06:45.36 (Ursi et al., GCN 28831)

About a week after GRB occurs, the brightness seems to remain nearly
constant, suggesting a possible onset of a supernova component accompanied
with GRB.

We thank all the operators at GECKO facilities for performing the
observation.

Gravitational-wave EM Counterpart Korean Observatory (GECKO) is a network
of 10+ 0.5m to 1m class telescopes over the world.