GCN Circular 38753
Subject
GRB 250101A: GMG Optical Observation
Event
Date
2025-01-01T14:19:34Z (a year ago)
Edited On
2025-01-02T02:02:08Z (a year ago)
From
Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>
Via
Web form
R.-Z. Li, B.-T. Wang, F.-F. Song, J. Mao, H. Lin and J.-M. Bai (YNAO, CAS) report:
We observed the field of GRB 250101A (Page et al., GCN 38752, T0 at 2025-01-01T13:22:50) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2025-01-01T14:00:24, about 0.63 hours after the trigger.
The optical counterpart of GRB 250101A, not visible in the Pan-STARRS1 r-band image, was clearly detected at the coordinates (J2000):
RA = 02 28 16.50
DEC = +19 11 39.4
, with a positional uncertainty of 0.5" or better. The position is consistent with UVOT position (GCN 38752).
The preliminary analysis results are shown as follows:
+----------------+------------+----------+--------------+----------------+
| Tmid-T0 [hr] | Exp. [s] | Filter | Mag | 5-sigma U.L. |
+================+============+==========+==============+================+
| 0.71 | 600 | r | 18.64 ± 0.01 | 22.2 |
+----------------+------------+----------+--------------+----------------+
The given magnitudes are derived based on calibration against Pan-STARRS1 field stars, and are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.1408 mag in the direction of the optical counterpart (Schlafly & Finkbeiner 2011).