TITLE: GCN CIRCULAR NUMBER: 43097 SUBJECT: GRB 251214B: Xinglong-2.16m optical observation DATE: 25/12/14 13:15:50 GMT FROM: syfu@nao.cas.cn

S.Y. Fu(HUST), D. Xu, Y.N. Zhu, P.L. Du, J.J. Jin, Z. Fan, X. Liu, L.B. He, J. An, S.Q. Jiang, Z.P. Zhu, J.J. Jia(NAOC)

We observed the field of GRB 251214B detected by Swift (Eyles-Ferris et al., GCN 43089) using the Xinglong-2.16m telescope equipped with the BFOSC camera. Observations started at 10:26:38 UT on 2025-12-14 (i.e., 1.41 h after the trigger), and a series of r- / g-band frames have been obtained.

The optical afterglow (Eyles-Ferris et al., GCN 43089; Kang et al., GCN 43093; Gress et al., GCN 43095) was clearly detected in our stacked frame with a magnitude of r = 19.40 +- 0.03 at a mid-time of 1.53 hr and g = 20.63 +- 0.09 at a mid-time of 1.88 hr, respectively, calibrated with Pan-STARRS1 DR2 catalog and not corrected for Galactic extinction.

We thank the staff at Xinglong observatory for their excellent support.

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