TITLE: GCN CIRCULAR NUMBER: 42051 SUBJECT: GRB 251001B: SVOM/VT optical observation DATE: 25/10/02 07:32:26 GMT FROM: Yinuo Ma mayn@bao.ac.cn
Y. N. Ma, L. P. Xin, Z. H. Yao, 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) report on behalf of the SVOM/VT team.
SVOM/VT performed a Target of Opportunity observation of GRB 251001B detected by Fermi/GBM and Swift/BAT (Fermi GBM team, GCN 42038; Beardmore et al., GCN 42039; Beardmore et al., GCN 42045; Neights & Meegan, GCN 42047). SVOM/VT began observing the field at 2025-10-01T15:03:04 UTC, 0.762 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With X-band data available, the optical counterpart (Gompertz et al., GCN 42040; An et al., GCN 42041; Strausbaugh & Cucchiara, GCN 42043; O'Neill et al., GCN 42046; Lipunov et al., GCN 42048; de Ugarte Postigo et al., GCN 42050) was clearly detected in both VT_B and VT_R bands. The magnitudes are:
mid time (h) | exposure time (s) | band | mag (AB) | mag err -------------|-------------------|------|----------|-------- 3.790 | 38*70 | VT_B | 22.06 | 0.09 3.819 | 35*70 | VT_R | 21.31 | 0.07
Our photometry was not corrected for Galactic extinction.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center 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.
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