TITLE:   GCN CIRCULAR
NUMBER:  22404
SUBJECT: GRB180205A: Optical observations with DOAO 1m telescope
DATE:    18/02/08 13:46:01 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

Changsu Choi, Myungshin Im (CEOU/SNU), Tae-Woo Kim, Wonseok Kang (KYSC), on
behalf of a larger collaboration.


We observed the field of GRB 180205A (Evans et al., GCN 22381) with the 1m
telescope of Deokheung Optical Astronomy Observatory (DOAO) in Korea,
starting from 2018/02/05 11:22:11 for three consecutive nights.

We obtained B, V, R-band images and clearly detected the afterglow in a
series of 300s exposure images. The afterglow in R band The afterglow is
dimming at a rate of about 0.75 mag per day fon average rom 02/05 to 02/07
(Evans et al., GCN 22381; Zheng et al. GCN 22382; Bolmer et al. GCN 22383;
Tanvir et al. GCN 22384; Volnova et al. GCN 22387; Falcon et al. GCN 22380;
Xin et al. GCN 22392; Zhu et al. GCN 22395; Emery et al. GCN 22396; Im et
al., GCN 22397; Oksanen et al. 22401; Mazaeva et al., GCN 22403).


Date UT mid Filter Exp. Mag(Vega) Err

2018-02-05 11:14:41 R 300s 19.47 0.12

2018-02-05 11:56:58 R 300s 19.48 0.08

2018-02-06 12:04:55 R 1200s 20.38 0.05

2018-02-06 14:07:30 R 1200s 20.29 0.04

2018-02-07 12:20:31 R 1200s 20.88 0.06

2018-02-07 13:57:28 R 1200s 21.14 0.07


The photometric calibration is based on the APASS stars within 6' radius
from GRB. The observation is continuing.