TITLE:   GCN CIRCULAR
NUMBER:  37771
SUBJECT: GRB 241010A: JinShan optical observations and potential host galaxy
DATE:    24/10/11 11:55:36 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, S.Y. Fu, X. Liu, J. An, Z.P. Zhu, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:

We observed the field of GRB 241010A detected by Swift (Dichiara et al. GCN 37755) using the 100C telescope of the JinShan project located at Altay, Xinjiang, China. A series of 300 s frames are obtained in the Sloan r-band, starting at 22:02:29.24 on 2024-10-10, i.e. 11.95 hr after the BAT trigger.

The optical afterglow (Dichiara et al. GCN 37755; Izzo et al. GCN 37756) of the burst is clearly detected in our stacked image. We measured a preliminary magnitude of r = 20.46 +/- 0.08 (AB), calibrated with nearby PanSTARRS stars. The magnitude is not corrected for Galactic extinction.

We also note that there exists a known source at the JinShan position in the Legacy Survey at coordinates R.A. (J2000) = 10:13:31.5317, Dec.(J2000) = +11:32:03.116, which is ~ 0.4 arcsec from the center of the UVOT position. The source has g = 23.0 +/- 0.05, r = 22.83 +/- 0.06, z = 22.13 +/- 0.09, a photometric redshfit of z = 0.87 +/- 0.11, and could be the host galaxy of the burst.

We acknowledge the excellent support from X. Yao, S.W. Luo, and Z.K. Feng for enabling these observations.