{
  "circularId": 43922,
  "submittedHow": "web",
  "createdOn": 1772701905906,
  "format": "text/plain",
  "bibcode": "2026GCN.43922....1B",
  "body": "\nM. Brunet, L. Bouchet (IRAP), Z. Wang, D. Kong(GXU) report on behalf of the SVOM/ECLAIRs team.\n\nUsing the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs observations of GRB 260303A (SVOM burst-id sb26030303 – GCN 43901, trigger time T0 = 2026-03-03T06:01:47 UTC).\n\nThe burst that triggered ECLAIRs shows a single peak lightcurve. The burst duration is estimated to be around 14.5s (from T0-19.5s to T0-5s) in the 4-120 keV energy band through imaging.\n\nThe refined burst localization is RA, Dec = 93.1458, 41.1727 degrees:\n\nRA (J2000) = 06h12m34.99s\nDec (J2000) = 41d10m21.72s\n\nwith a 90% C.L. radius of 9.6 arcmin (including systematic error of 6 arcmin added in quadrature).\n\nThe time-averaged spectrum from T0-19.5 s to T0-5 s in the energy range 5-120 keV is best fitted by a powerlaw model with a photon index of 1.67 +0.14/-0.13. With this model, the 4-120 keV fluence is  (1.19 +0.11/-0.20) e-6 erg/cm² and the 4-120 keV photon flux is 2.73 +0.16/-0.31 ph/cm²/s. \n\nAll the quoted errors are at the 68% confidence level.\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: Marius Brunet (IRAP) (marius.brunet at utoulouse.fr)\n",
  "eventId": "GRB 260303A",
  "submitter": "SVOM_group <svomgroup@bao.ac.cn>",
  "subject": "GRB 260303A: SVOM/ECLAIRs refined analysis"
}