TITLE: GCN CIRCULAR NUMBER: 39989 SUBJECT: GRB 250330B: EIRSAT-1 GMOD Detection DATE: 25/03/31 23:14:24 GMT FROM: David Murphy at University College Dublin <david.murphy@ucd.ie> D. Murphy, J. Fisher, C. de Barra, P. McDermott, C. McKenna, A. Ulyanov, G. Finneran, G. Corcoran, L. Cotter, A. Empey, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, on behalf of the EIRSAT-1 team: EIRSAT-1 reports the detection of the short gamma-ray burst GRB 250330B by the Gamma-ray Module (GMOD) instrument, which was also detected by Fermi GBM (GCN [39951](https://gcn.nasa.gov/circulars/39951)). The GMOD detection was made starting at 2025-03-30 21:52:22.4 UTC. The GMOD light curve for GRB250330B, with 1.2s binning, shows a single peak, consistent with the detection by Fermi GBM. The spacecraft location at time of detection was 1.704 S, 7.769 E and an altitude of 407.7 km. The light curve for this event as measured by GMOD can be found here: https://grb.eirsat1.ie/250330B/250330B_LC_onboard_preliminary.png EIRSAT-1 is Ireland’s first satellite ([Doyle et al. Proceedings of the 4th SSEA, 2022](https://researchrepository.ucd.ie/bitstreams/2f3fdccb-6e36-4ac1-88cd-4e80fee...)). 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](https://link.springer.com/article/10.1007/s10686-022-09842-z)). 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/39989. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...