GCN Circular 41430
Subject
GRB 250818B: TRT Optical Observation
Event
Date
2025-08-19T13:29:47Z (3 months ago)
From
Zipei Zhu at NAOC <zpzhu@nao.cas.cn>
Via
Web form
J. An (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Y. Fu (HUST), X. Liu, Z.P. Zhu, S.Q. Jiang, L.B. He, D. Xu (NAOC) report on behalf of a large collaboration:
We carried out two-epoch observations of GRB 250818B (Wang et al., GCN 41405), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Fresno, California, U.S.A (SRO) and New South Wales, Australia (SBO), respectively. And we obtained several frames in the B, V, R & I band.
The optical afterglow (Kumar et al., GCN 41406; Yao et al., GCN 41409; Zheng et al., GCN 41417; Bendtsen et al., GCN 41426; Moskvitin et al., GCN 41428) was clearly detected in our stack frames. The photometric results are presented in the following table:
|mid time(h)|filter|mag(Vega)|site|
|--|--|--|--|
|7.75|R|19.98+/-0.06|SRO|
|12.64|R|20.23+/-0.06|SBO|
The presented magnitudes are calibrated with Pan-STARRS DR2 catalog and not corrected for Galactic extinction.