TITLE: GCN CIRCULAR NUMBER: 40131 SUBJECT: GRB 250320B: cubesat Avion detection DATE: 25/04/10 08:46:40 GMT FROM: Andrey Bogomolov at Moscow State University <aabboogg@srd.sinp.msu.ru> A. Bogomolov, V. Bogomolov, A. Iyudin, S. Svertilov, N. Vasiliev on behalf of the MSU “Sozvezdie-270” team, report: At 2025-03-20 ~23:15:22 UT the long-duration GRB 250320B (Fermi GBM detection: GCN #39792; SVOM detection: GCN #39813, AstroSat CZTI detection: GCN #39808) was detected by the DeCoR-1 instrument on the cubesat Avion of the Moscow University project “Constellation-270” [1]. Total amount of photons detected by Avion is 1350 (energy band 40-500 keV), it corresponds to a fluence of ~6*10^(-6) erg/cm^2 in the range 40-500 keV. LC in the energy range of 40-500 keV has two main episodes with a maximum flux of ~5.8 phot/(cm^2*s) in the 1st peak with a duration of ~13 s, and ~5.2 phot/(cm^2*s) in the 2nd peak with a duration of ~11 s. А total duration (T90) of the burst is ~78 s. The light curve obtained by Avion is available here: https://swx.sinp.msu.ru/models/grb_cat/data/pictures/GRB20250320_Avion_DeCoR... Parameters of GRB 250320B as well as other GRBs detected by Moscow University cubesats are listed at: https://swx.sinp.msu.ru/models/grb_cat/grb.php?lang=en Avion is one of 5 cubesats of the Moscow University project “Constellation-270” [1] launched on 2023 June 27. The payload of Avion is a set of scintillation gamma-ray detectors DeCoR [2], the energy range is >30 keV, the time resolution is 0.5s. [1] Svertilov et al. 2023 https://link.springer.com/chapter/10.1007/978-3-031-50248-4_21 [2] Bogomolov et al. 2022 Universe 8, 282 https://www.mdpi.com/2218-1997/8/5/282 View this GCN Circular online at https://gcn.nasa.gov/circulars/40131. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...