GCN 45220: GRB 260727A: SVOM detection of a bright long burst

2026-07-27T00:58:53.073Z | rev 2 | event: GRB 260727A
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.

This burst does not satisfy the SVOM pointing constraints due to its angular separation from the Sun, and therefore no ToO follow-up observations will be performed by SVOM.

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.