GCN Circular 28713

Gregory S.H. Paek (CEOU/SNU), Myungshin Im (CEOU/SNU), Taewoo Kim, and
Wonseok Kang (DOAO) on behalf of a larger collaboration

We observed the optical counterpart of GRB 201020A (E. Ambrosi et al., GCN
#28696; R. Adachi et al., GCN #28697; J.P. Osborne et al., GCN #28698; V.
Lipunov et al., GCN #27800, S.Y. Fu et al., GCN #28701; S. Belkin et al.,
GCN #28703, T. Pankov et al., GCN #28708, and H. Kumar et al., GCN #28711)
with the 1-m class telescope in Deokheung Optical Astronomy Observatory
(DOAO). We calibrated flux with PS1 catalog and use AB magnitude system.

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Mid Date[UT] Mid t-t0[days] Filter Exp.time[s] Mag Error
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2020-10-20 10:28:07 0.195 V 300*3 19.361 0.059
2020-10-20 10:33:21 0.199 R 300*3 19.006 0.042
2020-10-20 10:38:35 0.202 I 300*3 18.767 0.039

t0 : 2020-10-20 05:47:26 UT (E. Ambrosi et al., GCN #28696)

The magnitudes are not corrected for galactic extinction.