GCN Circular 37460
Subject
GRB 240910A: JinShan optical observations
Date
2024-09-11T20:17:44Z (a month ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Via
Web form
S.Q. Jiang, X. Liu, J. An, Z.P. Zhu, S.Y. Fu, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the Swift/XRT ToO field (Evans, GCN 37456) of GRB 240910A detected by Fermi/GBM (Fermi GBM team, GCN 37441), SVOM/GRM (Zhang et al., GCN 37445), and GRBAlpha (Ripa et al., GCN 37450), using the 100C telescope of the JinShan project, located at Altay, Xinjiang, China. We obtained 8 x 300 s frames in the Sloan r-filter at a median time of 1.55 days after the Fermi/GBM trigger.
An uncatalogued optical transient is detected within the Swift/XRT Source #2 error circle (01h36m23.32s, -00°12′17.1″, radius ~ 4.0′′) at coordinates
R.A.(J2000) = 01:36:23.47
Dec.(J2000) = -00:12:17.24
with an uncertainty of ~ 0.4 arcsec, being consistent with the GOTO position (Julakanti et al., GCN 37459). It has r ~ 20.9 mag (AB), calibrated with the nearby PanSTARRS stars. The decay rate of the OT, in comparison with the previous GOTO brightness, is consistent with that for GRB optical afterglows. We thus conclude that the OT is very likely the optical afterglow of GRB 240910A.
We acknowledge the excellent support from X. Yao, S.W. Luo, and Z.K. Feng for enabling these observations.