TITLE: GCN CIRCULAR NUMBER: 39890 SUBJECT: GRB 250327B: SVOM/VT optically bright counterpart DATE: 25/03/27 22:50:19 GMT FROM: Liping Xin at NAOC, SVOM xlp@nao.cas.cn
L.P. Xin, Y. L. Qiu, H. L. Li, C. Wu (NAOC),J. T. Palmerio(CEA/Irfu), Z. H. Yao, Y. Xu, P. P. Zhang, W. J. Xie, J. Wang, X. H. Han, Y. J. Xiao, H. B. Cai, J. Y. Wei (NAOC), Laurent Bouchet, Hui Yang(IRAP) report on behalf of the SVOM team:
SVOM performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Bouchet et al., GCN 39888). SVOM/VT began observing the field automatically with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With VHF downlinked data, a very bright uncatalogued source was found in both channels, and brightening in the first and second sequences, compared to DESI catalog.
The coordinates are R.A =11:47:06.70, DEC.=+29:50:24.8 Error=0.5 arcseconds. J2000
The magnitude is VT_B~15.8 mag(AB) and VT_R~14.2 mag(AB) in the first sequence with the mid time of 461 seconds after the burst.
The coordinates and the brightness are consistent with the candidate reported (Moskvitin et al., GCN 39889).
We proposed that this is the optical counterpart of the burst.
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.
View this GCN Circular online at https://gcn.nasa.gov/circulars/39890. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...