TITLE: GCN CIRCULAR NUMBER: 44532 SUBJECT: GRB 260511A: SVOM detection of a bright burst DATE: 26/05/11 06:37:49 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> O. Godet, M. Brunet (IRAP), L. Zhang (IHEP), D. Kong (GXU) report on behalf of the SVOM mission team: At 2026-05-11T06:13:32 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260511A (SVOM burst-id sb26051101). This transient was also detected by Fermi/GM (GCN Circular 44529). 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 16 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 55.22 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2026-05-11T06:13:32. The localization of the best alert is R.A., Dec. 197.929, -33.853 degrees (J2000) with a 90% confidence level (C.L.) radius of 2.44 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/ECLAIRs light curve showed a single/multiple broad/narrow peak structure with a T90 duration of about 13.5 (-0.4/ +0.6) s in the 5-120 keV. This burst also triggered SVOM/GRM at 2026-05-11T06:13:30 on a timescale of 1 seconds with an SNR of 12.10. The SVOM/GRM light curve showed a multiple peak structure with a T90 duration of about 14.3 (-0.4 / +0.8) s in the 8-1100 keV. SVOM slewed to the burst. SVOM/MXT began observing the field at 2026-05-11T06:16:38 UTC, 186 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 197.9145, -33.8120 degrees: R.A. (J2000) = 13h11m39.48s Dec. (J2000) = -33d48m43.09s with a 90% C.L. radius of 39.05 arcseconds. This location is 2.54 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published 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 zhangli: zhangli at ihep.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/44532. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...