TITLE: GCN CIRCULAR NUMBER: 44527 SUBJECT: GRB 260510C: SVOM/VT optical upper limits DATE: 26/05/11 01:03:32 GMT FROM: Huali Li at at NAOC, SVOM <lhl@nao.cas.cn> 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. SVOM/VT performed automatic observations of GRB260510C triggered by SVOM/ECLAIRs (sb26051004, Gotz et al., GCN 44521). The burst was also detected by Fermi GBM (Fermi GBM team, GCN 44520) and MAXI/GSC (Iwakiri et al., GCN 44526). The VT observations started at 2026-05-10T17:18:48 UTC, i.e., 304 seconds post trigger, in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. No uncatalogued sources were detected within the error box of SVOM/MXT (Gotz et al., GCN 44521) and SVOM/ECLAIRs (Gotz et al., GCN 44521), compared to the Legacy Survey. The following measurements are in the AB magnitude and are not corrected for Galactic extinction: Mid time | Band | Exposure Time | 3 sigma upper limit 1.10 h VT_B 47*50 sec > 23.2 mag 1.18 h VT_R 41*50 sec > 23.1 mag Further analyses are ongoing. 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/44527. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...