GCN Circular 41390
Subject
GRB 250812A: SVOM/VT optical continued observation
Event
Date
2025-08-15T10:57:59Z (6 days ago)
From
Yinuo Ma <mayn@bao.ac.cn>
Via
Web form
Y. N. Ma, Z. H. Yao, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), Z. M. Wang (BNU) report on behalf of the SVOM/VT team.
SVOM/VT conducted continued observations of GRB 250812A detected by SVOM/ECLAIRs（Xin et al., GCN 41322). The magnitudes of the optical afterglow (He et al., GCN 41324; Xin et al., GCN 41326; Rakotondrainibe et al., GCN 41328; Freeberg et al., GCN 41331; Siegel et al., GCN 41344; Santos et al., GCN 41346; van Dalen et al., GCN 41347; de Ugarte Postigo et al., GCN 41348) are:
mid time (h) | exposure time (s) | band | mag (AB) | mag err
-------------|-------------------|-- ---|----------|--------
66.572 | 20*70 | VT_R | 21.25 | 0.07
66.572 | 20*70 | VT_B | 21.81 | 0.09
Our photometry was not corrected for Galactic extinction.
The optical afterglow initially rises with a temporal slope of 0.5, reaching its peak at approximately 18 hours, followed by a rapid decay with a slope of -2.0.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.