{
  "eventId": "sb25061207",
  "submittedHow": "web",
  "bibcode": "2025GCN.40816....1G",
  "format": "text/plain",
  "subject": "sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis",
  "circularId": 40816,
  "createdOn": 1750763047817,
  "submitter": "ogodet@irap.omp.eu",
  "body": "Authors: O. Godet (IRAP), N. Dagoneau (CEA), F. Cangemi (APC), M. Brunet (IRAP), L. Zhang (IHEP), Y.-D. Hu (GXU), X.-L. Chen (YNU)\n\n\n\nUsing the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the event sb25061207 that we confirm to be a GRB (GRB 250612D) based on the detection of a fading afterglow in both visible (GCN #40707) and X-rays (GCN #40718). \n\n\nThe burst that triggered ECLAIRs onboard (GCN #40697) displays a faint and soft emission with most photons emitted below 20 keV. The duration of this event is around 32 s in the 4-20 keV energy band. \n\n\nThe time-averaged spectrum from T0-32s to T0 (T0 = 2025-06-12T10:27:22 UTC) in the energy range 5-20 keV is best fitted by a powerlaw model with a photon index = 1.7 +/-0.3. With this model, the total 4-120 keV fluence is (7.4 +0.3/-4.2)e-7 erg/cm^2.\n\n\nAll the quoted errors are at the 68% confidence level.\n\nWe note that the calibration of SVOM/ECLAIRs is undergoing thus these results are 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\n\nThe SVOM/ECLAIRs point of contact for this burst is: Olivier Godet (IRAP) (ogodet at irap.omp.eu)\n\n"
}