TITLE: GCN CIRCULAR NUMBER: 38423 SUBJECT: GRB 241130A: EIRSAT-1 GMOD Detection DATE: 24/12/02 20:06:55 GMT FROM: Padraig McDermott at University College Dublin padraig.mcdermott@ucdconnect.ie

P. McDermott, C. McKenna, D. Murphy, C. de Barra, A. Ulyanov, M. Doyle, R. Dunwoody, J. Mangan, 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:

EIRSAT-1 reports the detection of the long gamma-ray burst GRB241130A by the Gamma-ray Module (GMOD) instrument, which was also reported by Fermi GBM (GCN 38421 and 38406). The GMOD detection was made at 24-11-30 23:13:44.3 UTC.

The GMOD light curve for GRB241130A, with 1.2s binning, shows a single peak. The spacecraft location at time of detection was 36.002 N, 21.890 W and an altitude of 453 km. The light curve for this event as measured by GMOD can be found here: https://grb.eirsat1.ie/241130A/241130A_LC_onboard_preliminary.png

A bright FRED-like pulse can also be seen in the SPI-ACS ([Rau et al, Astronomy & Astrophysics, 438(3). 1175-1183. 2005](https://www.aanda.org/articles/aa/abs/2005/30/aa3159-05/aa3159-05.html)) light curve at a consistent time (SPI-ACS data can be retrieved using the following [link](https://www.astro.unige.ch/mmoda/?DEC=-29.74516667&RA=265.97845833&T...)).

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.

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