TITLE: GCN CIRCULAR NUMBER: 42848 SUBJECT: GRB 251126A: Nanshan/HMT optical afterglow detection DATE: 25/11/26 21:01:26 GMT FROM: syfu@nao.cas.cn
S.Y. Fu (HUST), S.Q. Jiang, J. An, X. Liu, L.B. He, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 251126A detected by Swift/BAT (Caputo et al., GCN 42843) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 19:11:52 UT on 2025-11-26, i.e., 76 seconds after the Swift/BAT trigger, and a series of unfiltered frames with different exposures were obtained.
An uncatalogued and varying optical source is detected within the XRT error circle (Caputo et al., GCN 42843) at coordinates:
R.A.(J2000) = 06:39:46.56 Dec.(J2000) = +54:59:12.27
with an uncertainty of ~0.5 arcsec. This position is consistent with the previous report by GIT (Swain, GCN 42844). The source has ~ 19.0 mag in the first image, calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction. The early light curve initially shows a slow rise, reaching a peak at ~150s, and then decays with power law index of ~0.5. Thus, we conclude that the source is the afterglow of GRB 251126A.
Observations are still ongoing.
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