{
  "body": "P. McDermott, D. Murphy, C. McKenna, C. de Barra, A. Ulyanov, G. Finneran, G. Corcoran, L. Cotter, A. Empey, J. Fisher, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, on behalf of the EIRSAT-1 team: \n\nEIRSAT-1 reports the detection of the long gamma-ray burst GRB 250504A by the Gamma-ray Module (GMOD) instrument, which was also detected by Fermi GBM (GCN [40342](https://gcn.nasa.gov/circulars/40342) and [40346](https://gcn.nasa.gov/circulars/40346)) and Swift-BAT (GCN [40343](https://gcn.nasa.gov/circulars/40343)).  The GMOD detection was made starting at 2025-05-04 23:25:56.5 UTC.\n\nThe GMOD light curve for GRB 250405A, with 1.2s binning, shows multiple peaks consistent with the detections by Fermi GBM and Swift-BAT.\n\nThe spacecraft location at time of detection was  9.886º S, 164.567° E and an altitude of 386 km.\n\nThe light curve for this event as measured by GMOD can be found here:\nhttps://grb.eirsat1.ie/250504A/250504A_LC_onboard_preliminary.png\n\nEIRSAT-1 is Ireland’s first satellite (Doyle et al. Proceedings of the 4th SSEA, 2022). It is a 2U CubeSat and carries onboard a number of experiments including the Gamma-Ray Module (GMOD), a novel, compact, gamma-ray detector (Murphy et al, Experimental Astronomy, 53, 961–990, 2022). GMOD consists of a 25 mm × 25 mm × 40 mm Cerium Bromide scintillator coupled to SiPMs and is designed to detect gamma-ray bursts in the ~ 60 keV - 1.5 MeV range. EIRSAT-1 was developed in University College Dublin with support from ESA’s Fly Your Satellite! programme and was launched on 1st December 2023.",
  "bibcode": "2025GCN.40372....1M",
  "submittedHow": "web",
  "circularId": 40372,
  "format": "text/markdown",
  "subject": "GRB 250504A: EIRSAT-1 GMOD Detection",
  "submitter": "Padraig McDermott at University College Dublin <padraig.mcdermott@ucdconnect.ie>",
  "eventId": "GRB 250504A",
  "createdOn": 1746565439160
}