TITLE: GCN CIRCULAR NUMBER: 45504 SUBJECT: GRB 260903A: SVOM/VT optical candidate DATE: 26/09/03 19:00:22 GMT FROM: Huali Li at at NAOC, SVOM <lhl@nao.cas.cn> H. L. Li, C. Wu, L. P. Xin, Y. L. Qiu, Y. N. Ma, Z. H. Yao, J. R. Xu, L. S. Chen, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio, A. Saccardi (CEA/Irfu), R.-C. Chen (NJU), T. Xiao (GXU) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observations of GRB 260903A detected by SVOM/ECLAIRs (sb26090302, Brunet et al., GCN 45499). Our observation started on 2026-09-03T14:41:46 UT (about 2.1 hr after the trigger) in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously . An uncatalogued optical source compared to the Legacy Survey catalogue was identified in our images within the ECLAIRs localization error circle (Brunet et al., GCN 45499). Its position is R.A., Dec. = 25.662357, 11.370481 degrees: R.A. (J2000) = +01:42:38.96 Dec. (J2000) = +11:22:13.73 with a positional uncertainty of ~0.5 arcsec. The following measurements are in the AB magnitude and are not corrected for Galactic extinction: Mid time | Band | Exposure Time | Brightness 2.18 hr VT_B 11*70 s 21.9 +/- 0.2 mag 2.18 hr VT_R 11*70 s 20.7 +/- 0.1 mag No significant positional or brightness variation of the candidate was detected over our nearly 2‑hour observations. More follow-up observations of this burst are scheduled. 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/45504. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...