TITLE: GCN CIRCULAR NUMBER: 45220 SUBJECT: GRB 260727A: SVOM detection of a bright long burst DATE: 26/07/27 00:58:53 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> An Li (BNU), Yifang Liang (PMO), Wenjin Xie (NAOC), Donghua Zhao (NAOC), Clara Plasse (HKU), Ruizhi Li (YNAO), Ziming Wang (BNU) report on behalf of the SVOM mission team: At 2026-07-27T00:22:02 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260727A (SVOM burst-id sb26072701). 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 41 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 111.24 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2026-07-27T00:21:34. The localization of the best alert is R.A., Dec. 331.6445, 74.5406 degrees: R.A. (J2000) = 22h06m34.69s Dec. (J2000) = 74d32m25.98s with a 90% confidence level (C.L.) radius of 2.12 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/ECLAIRs light curve showed a multiple peak structure with long duration. The SVOM/GRM light curve showed a multiple broad peak structure with long duration. Due to another ongoing GRB observation, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being.No optical observation could be performed by SVOM/VT for the time being. 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 Ziming Wang: 202421101144@mail.bnu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45220. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...