TITLE:   GCN CIRCULAR
NUMBER:  26431
SUBJECT: LIGO/Virgo S191213g: Lulin Follow-up Observations of ZTF19acykzsk/AT2019wqj
DATE:    19/12/15 02:17:28 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

Han-Jie Tan (NCU), Albert Kong (NTHU), Chow-Choong Ngeow (NCU),
Wing-Huen Ip (NCU)

On behalf of the Global Relay of Observatories Watching Transients
Happen (GROWTH) collaborations

We report the photometric measurements of the Type II supernova
ZTF19acykzsk/AT2019wqj previously associated with the gravitational
wave event S191213g (GCN #26402, #26424) using the Lulin One-meter
Telescope (LOT) in Taiwan. The observations were conducted using g, r,
i filters starting at 2019-12-14 10:13:37 UT and were repeated 7 hours
later. Preliminary photometry was obtained by calibrating with the
APASS catalog.

Its r magnitude is slightly fainter than the observation by Andreoni
et al. (GCN #26424) ~14hr earlier and suggests a slow decay. We
confirm the report from Andreoni of a red color g-r=0.26.

Summary of ZTF19acykzsk/AT2019wqj :
UT                     JD          Filter    Exp(s)      Mag (AB)
2019-12-14 10:16:07  2458831.928   g         300         19.37+/-0.10
2019-12-14 10:21:13  2458831.931   r          300         19.11+/-0.16
2019-12-14 10:26:20  2458831.935   i          300         19.10+/-0.11
2019-12-14 17:21:07  2458832.223   g        300*2       19.51+/-0.11
2019-12-14 17:32:47  2458832.231   r         300*2       19.10+/-0.14
2019-12-14 17:35:24  2458832.233   i          300         19.06+/-0.24

We would like to thank the staff in Lulin Observatory for helping the
observations.