GCN 44540: GRB 260510C: SVOM/VT optical counterpart confirmation

H. L. Li, L. P. Xin, C. Wu, Y. L. Qiu, Y. N. Ma, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.

We refined the analysis of SVOM/VT images (Li et al., GCN 44527) on GRB 260510C (Gotz et al., GCN 44521; Fermi GBM team, GCN 44520; Iwakiri et al., GCN 44526) with more data available. The optical counterpart found by SVOM/COLIBRÍ (Angulo et al., GCN 44530) was clearly detected in both channels of SVOM/VT. The following measurements are in the AB magnitude and are not corrected for Galactic extinction:

Mid time | Band  | Exposure Time | Brightness
1.79 h     VT_B     40*50 sec      21.13 +/- 0.09 mag
1.18 h     VT_R     41*50 sec      19.94 +/- 0.06 mag    
8.06 h	   VT_B     9*100 sec      22.13 +/- 0.14 mag
8.14 h     VT_R     3*100 sec	   20.61 +/- 0.08 mag

The source showed a fading slope of about -0.45 during the observations above.

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.