GCN Circular 21907
Subject
GRB 170921A: Nanshan optical upper limit
Event
Date
2017-09-22T00:33:24Z (9 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
H.X. Feng (NAOC), Y.D. Hu (IAA-CSIC), D. Xu, Z.P. Zhu (NAOC), X. Zhang, T.Z. Yang, J.Z. Liu, A. Esamdin, L. Ma (XAO), Y. Qin (Geneva Obs.) report:�� We observed the field of long GRB 170921A (D'Ai et al., GCN 21901)��using the 1m telescope located at Nanshan, Xinjiang, China. We obtained��3*180s R-band frames, starting at 15:52:35.04 UT on 2017-09-21 (i.e., 1.39 hr after the BATtrigger).�� No optical source is detected at the XRT position (Beardmore et al., GCN 21906) in the stacked image, down to a limiting magnitude of m(R)~20.3,��calibrated with the USNO-B1 catalog.��