TITLE:   GCN CIRCULAR
NUMBER:  25659
SUBJECT: LIGO/Virgo S190901ap: Dabancheng-0.5m optical observations of AT2019pjv
DATE:    19/09/04 16:53:06 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

B.Y. Yu, D. Xu, Z.P. Zhu, T.M. Zhang, X. Zhou, H.J. Wang, C.Z. Cui, D.W. 
Fan, Y.F. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), Z.B. Zhang 
(XJTS), S. Yang (Stockholm U.), H.B. Zhao, B. Li (PMO), J.Z. Liu, H.B. 
Niu (XAO), J.R. Mao,
J.M. Bai (YNAO), report on behalf of the GWFUNC collaboration:

We observed the optical transient AT2019pjv, a candidate of the optical 
counterpart of LIGO/Virgo S2019091ap (MASTER, Lipunov et al. GCN #25649; 
GOTO, Ackley et al., GCN #25654), using the Half Meter Telescope (HMT) 
located at Dabancheng, Xinjiang, China. Observations started at 14:31:01 
UT on 2019-09-04, and 5x150 s unfiltered frames were obtained.

The OT is clearly detected in each exposure, and we got m(r) = 18.00 +/- 
0.05 mag in the stacked image, calibrated with nearby PanSTARRS field.

In comparison with previous MASTER and GOTO measurements, the OT has 
been rising since its detection on Sep 2. Such behaviour is much more 
consistent with a young supernova than an optical afterglow of a short 
GRB or a kilonova.