TITLE: GCN CIRCULAR NUMBER: 44975 SUBJECT: GRB 260506B: cubesat Avion detection DATE: 26/06/18 09:57:49 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> A. Bogomolov, V. Bogomolov, A. Iyudin, S. Svertilov, N. Vasiliev on behalf of the MSU “Sozvezdie-270” team, report: At 2026-05-06 ~13:07:28 UT the long-duration GRB 260506B (Fermi GBM detection: GCN #44484, AstroSat CZTI detection: GCN #44503, Glowbug detection: GCN #44559) was detected by the DeCoR-3 instrument on the cubesat Avion of the Moscow University project “Sozvezdie-270” [1]. Total amount of photons detected by Avion is 428 (energy band >30 keV), it corresponds to a fluence of ~3.8*10^(-6) erg/cm^2 in the range 30-500 keV. LC in the energy range of 30-500 keV has a multiple peak structure including a faint peak of ~1 s duration at ~13:07:29 with a maximum flux of ~60 phot/(cm^2*s) and a main peak of ~5 s duration at ~13:07:40 with a maximum flux of ~80 phot/(cm^2*s) at ~13:07:42 UT. А total duration (T90) of the burst is ~15 s. The light curve obtained by Avion is available here: https://swx.sinp.msu.ru/models/grb_cat/data/pictures/GRB260506B_LC_Avion.png Parameters of GRB 260506B 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/44975. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...