GCN Circular 42331
Subject
GRB 251017A: JinShan observations of the optical afterglow
Event
Date
2025-10-17T18:35:37Z (19 days ago)
From
syfu@nao.cas.cn
Via
Web form
S.Y. Fu (HUST), L.B. He, X. Liu, J. An, S.Q. Jiang, Z.P. Zhu, D. Xu (NAOC), A.D. Zhu, L. Lei, H.Z. Wu (HUST), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of Swift GRB 251017A (Gupta et al., GCN 42322) using the 100C telescope of the JinShan project, located at Altay, Xinjiang, China. Observations started at 2025-10-17 12:50:19.42 UT, i.e., 4.16 hours after the trigger, and a series of 300s frames in r and z bands were obtained.
The previously reported optical afterglow (Perez-Garcia et al., GCN 42323; Antier et al., GCN 42325; Sasada et al., GCN 42329) was clearly detected in our images with r-band magnitude r = 21.17 +- 0.06, calibrated with nearby Pan-STARRS1 DR2 catalog and without the Galactic extinction correction.
We acknowledge the excellent support from T.Q. Chen and J.F. Zhang for enabling these observations.