TITLE:   GCN CIRCULAR
NUMBER:  42041
SUBJECT: GRB 251001B: TRT optical afterglow detection and potential host galaxy
DATE:    25/10/01 15:17:04 GMT
FROM:    sqjiang at NAOC <sqjiang@bao.ac.cn>

J. An, X. Liu (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Q. Jiang, L.B. He, Z.P. Zhu, D. Xu (NAOC), S.Y. Fu (HUST) report on behalf of a large collaboration:

We observed the field of GRB 251001B detected by Swift/BAT (Beardmore et al., GCN 42039), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). A series of images were obtained in the R band.

A varying optical transient (OT) is detected within the Swift/XRT error circle at coordinates

R.A. (J2000) = 2:50:36.33
Dec.(J2000) = -23:01:11.96

with an uncertainty of ~ 0.6 arcsec. It has R ~ 18.9 mag at 21.1 min after the Swift/BAT trigger. We thus think the OT is the optical afterglow of the burst.

We also note that there is a galaxy at the OT position from Legacy Survey DR10 with g ~ 25.16, r ~ 24.93, i ~25.06, z ~24.79, and a phot_z ~ 1.14 +/- 0.53, which is presumably the host galaxy of the burst.