TITLE: GCN CIRCULAR NUMBER: 44405 SUBJECT: GRB 260401A: cubesat Avion detection DATE: 26/04/24 23:43:29 GMT FROM: Andrey Bogomolov at Moscow State University <aabboogg@srd.sinp.msu.ru> From Andrey Bogomolov at Moscow State University <aabboogg@srd.sinp.msu.ru> Subject GRB 260401A: cubesat Avion detection A. Bogomolov, V. Bogomolov, A. Iyudin, S. Svertilov, N. Vasiliev on behalf of the MSU “Sozvezdie-270” team, report: At 2026-04-01 ~10:53:20 UT the long-duration GRB 260401A (Fermi GBM detection: GCN #44174, CALET detection: GCN #44177, GECAM-B detection: GCN #44187, SVOM detection: GCN #44188) was detected by the DeCoR-1 and DeCoR-3 instruments on the cubesat Avion of the Moscow University project “Sozvezdie-270” [1]. Total amount of photons detected by Avion is 256 (DeCoR-1, energy band 40-500 keV) and 526 (DeCoR-3, energy band >30 keV), it corresponds to a fluence of ~4.7*10^(-6) erg/cm^2 in the range 30-500 keV. LC in the energy range of 30-500 keV is a sharp peak of ~4 sec duration with a maximum flux of ~20 phot/(cm^2*s) at ~10:53:28 UT with increases of smaller amplitude before (10:53:20-10:53:24 UT) and after it (10:53:36-10:53:43 UT). А total duration (T90) of the burst is ~21 s. The light curve obtained by Avion is available here: https://swx.sinp.msu.ru/models/grb_cat/data/pictures/GRB260401A_LC_Avion.png Parameters of GRB 260401A 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 “Sozvezdie-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/44405. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...