GCN Circular 22661
Subject
GRB 180418A: Xinglong TNT optical upper limit
Date
2018-04-19T02:51:03Z (6 years ago)
From
L.P. Xin at NAOC <xlp@nao.cas.cn>
L. P. Xin, J. Z. Yan, J. Y. Wei, Y. L. Qiu, J. S. Deng,
J. Wang, X. H. Han, X. M. Meng, C. Wu, D. TURPIN, H. L. Li report:
We began to observe GRB 180418A (D'Elia et al., GCN 22646)
with Xinglong 0.8-m TNT telescope, China, at 2018-04-18, 14:23:11(UT),
about 7.8 hours after the burst.
We obtained 10 R-band images with an exposure time of 300 sec for each frame.
The optical afterglow (Zheng & Filippenko, GCN 22647;
Guidorzi et al., GCN 22648; Troja et al., GCN 22652; Fong et al., GCN
22659; Malesani et al., GCN 22660 ) was not detected in our stacked image with 10*300 sec.
The 3 sigma upper limit is estimated to be about R~20 mag calibrated
by USNO B1.0 R2 mag at about 8.2 hours after the burst,
We acknowledge the excellent support from Xinglong staff YunPeng Wang.