TITLE: GCN CIRCULAR NUMBER: 41134 SUBJECT: GRB 250713A : SVOM/ECLAIRs refined analysis DATE: 25/07/22 11:09:53 GMT FROM: SVOM_group svomgroup@bao.ac.cn

M. Brunet, L. Bouchet (IRAP), F. Cangemi (APC), P. Maggi (ObAS) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the long GRB 250713A (SVOM burst-id sb25071320),

The burst that triggered ECLAIRs [onboard/ onground] (GCN #41078) consists of a single peak with a duration of at least 60s visible in the 4-60 keV energy band.

The time-averaged spectrum from T0-10s s to T0+32s (T0 = 2025-07-13T17:06:26) in the energy range 4-60 keV is best fitted by a black body model with kT = 4.91 +0.32/-0.30 keV . With this model, the total 4-120 keV fluence is 1.10 +0.07/-0.10 e-8 erg/cm^2.

A Broken Power-law also gives a decent fit with a photon index of 1.08 +0.16/-0.18 before the break, a break energy of 21.50 +3.41/-2.76 keV and a photon index of 3.23 +0.81/-0.53 after the break. In that case, the total 4-120 keV fluence is 1.25 +0.06/-0.18 e-8 erg/cm^2.

A preliminary time-resolved spectral analysis shows a decrease in the black body temperature from kT = 6.73 +0.72/-0.64 keV to kT =2.72 +0.45/-0.36 keV over the first 42 seconds of the burst duration. At the same time the source radius increases by a factor 4.3 +1.3/-1.7.

All the quoted errors are at the 68% confidence level.

We note that the calibration of SVOM/ECLAIRs is undergoing thus these results are preliminary. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC.

The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (mbrunet at irap.omp.eu)

View this GCN Circular online at https://gcn.nasa.gov/circulars/41134. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...