TITLE: GCN CIRCULAR NUMBER: 45298 SUBJECT: GRB 260715A: cubesat Avion detection DATE: 26/08/06 08:51:32 GMT FROM: Andrey Bogomolov at Moscow State University From Andrey Bogomolov at Moscow State University A. Bogomolov, V. Bogomolov, A. Iyudin, S. Svertilov, N. Vasiliev on behalf of the MSU “Sozvezdie-270” team, report: At 2026-07-15 ~11:10:14 UT the long-duration GRB 260715A (Fermi/GBM detection: GCN #45167) 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 198 (energy band >30 keV), it corresponds to a fluence of ~1.75*10^(-6) erg/cm^2 in the range 30-500 keV. LC in the energy range of 30-500 keV consists of a single episode with a rapid front and a smoother decline, a maximum flux is ~3.8 phot/(cm^2*s). There is probably another increase ~13 s after the start of the burst. 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/GRB260715A_LC_Avion.png Parameters of GRB 260715A 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. 2026 Cosmic Research 64, 262 https://link.springer.com/article/10.1134/S0010952526600071