TITLE: GCN CIRCULAR NUMBER: 41430 SUBJECT: GRB 250818B: TRT Optical Observation DATE: 25/08/19 13:29:47 GMT FROM: Zipei Zhu at NAOC zpzhu@nao.cas.cn
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.
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