TITLE: GCN CIRCULAR NUMBER: 46072 SUBJECT: GRB 261029A: SVOM detection of a burst DATE: 26/10/29 02:02:11 GMT FROM: SVOM_group Hatsune Goto (RIKEN/CEA), Hanrui He (PMO), Clara Plasse (HKU), Wenjin Xie (NAOC), Yifang Liang (PMO), Zhiyong Liu (GZNU) report on behalf of the SVOM mission team: At 2026-10-29T01:27:07 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 261029A (SVOM burst-id sb26102901). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 19 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 58.13 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2026-10-29T01:27:04. The localization of the best alert is R.A., Dec. 8.8858, 34.5603 degrees: R.A. (J2000) = 0h35m32.60s Dec. (J2000) = 34d33m37.05s with a 90% confidence level (C.L.) radius of 2.40 arcmin (including systematic error of 2 arcmin added in quadrature). This burst also triggered SVOM/GRM at 2026-10-29T01:27:04. Detailed analysis results will be reported in future. This burst is consistent in time and position with Fermi/GBM detection at 01:27:03 UTC (GCN #46071). SVOM slewed to the burst. At the time of the trigger, MXT was in Earth occultation. Observations performed by SVOM/MXT and SVOM/VT will be reported in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Yifang Liang: yfliang@pmo.ac.cn. Please contact the BA by email if you require additional information.