{
  "submittedHow": "web",
  "circularId": 40695,
  "createdOn": 1749713993249,
  "format": "text/plain",
  "submitter": "ogodet@irap.omp.eu",
  "bibcode": "2025GCN.40695....1G",
  "subject": "GRB 250610B - SVOM/ECLAIRs refined analysis",
  "eventId": "GRB 250610B",
  "body": "Authors: O. Godet (IRAP), A. Coleiro (APC), M.-G. Bernardini (INAF-OAB, LUPM), A. Saccardi (CEA), J. Rodriguez (CEA)\n \nUsing the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 250610B (SVOM burst-id sb25061018). \n\nThe burst that triggered ECLAIRs onboard (GCN #40671) consists of a single large peak with a duration of T90 = 108.25 -13.14 / +34.95 s in the 4-120 keV energy band. \n\nThe time-averaged spectrum from T0-10s to T0+80s (T0 = 2025-06-10T16:32:58 UTC) in the energy range 5-120 keV is best fitted by a cutoff powerlaw model with a photon index of 0.9 +/- 0.1 and a cutoff energy of 49 +14/-10 keV. This translates to a Epeak-value of 53 +16/-12 keV. These spectral parameters are consistent with those obtained by SVOM/GRM (GCN #40683). With this model, the total 4-120 keV fluence is (2.9 +0.1/-0.4)e-6 erg/cm^2.\n\nAll the quoted errors are given at the 68% confidence level.\n\nGiven that the ECLAIRs calibration is still on-going, the above results shall be seen as preliminary.  \n\nThe 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.\n\nThe SVOM/ECLAIRs point of contact for this burst is: O. Godet (IRAP) (ogodet at irap.omp.eu)\n"
}