TITLE: GCN CIRCULAR NUMBER: 44295 SUBJECT: EP260321a: CMO SAI J,K observations DATE: 26/04/14 11:27:29 GMT FROM: Alina Volnova at IKI RAS <alinusss@gmail.com> A.A. Volnova (IKI), A.M. Tatarnikov (SAI MSU), S.G. Zheltoukhov (SAI MSU), A.S. Pozanenko (IKI), N.S. Pankov (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the fast X-Ray transient EP260321a (Huang et al., GCNs 44068, 44075) at z = 0.0343 (Tanvir et al., GCN 44082) with SAI-2.5 (2.5m) telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute (CMO SAI), equipped with the IR camera ASTRONIRCAM. The observations in the J and K filters were carried out on 2026-04-02, and in J filter on 2026-04-07. The Supernova reported previously (Lee et al., GCN 44070; Ma et al., GCN 44074; Aguilar-Ruiz et al., GCN 44076; Liang et al., GCN 44079; Aryan et al., GCN 44081; Tanvir et al., GCN 44082; Moran et al., GCN 44083, Ahumada et al., GCN 44084, Liu et al., GCN 44087; Sankar et al. GCN 44089; de Ugarte Postigo et al., GCN 44091; Xu et al., GCN 44092; Pankov et al. GCN 44103; Corcoran et al., GCN 44105; Rastinejad et al., GCN 44107; Gao et al., GCN 44110; He et al., GCN 44117; Zhang et al., GCN 44171; Li et al., GCN 44284) is clearly detected in stacked frames. Preliminary photometry and observational details are the following: Date UT_start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-04-02 21:11:47 12.36569 6*96 J 16.76 0.04 20.5 CMO SAI/SAI-2.5 2026-04-02 20:58:27 12.35698 20*29 K 16.50 0.06 19.1 CMO SAI/SAI-2.5 2026-04-07 17:53:10 17.23089 11*96 J 16.45 0.04 21.1 CMO SAI/SAI-2.5 The photometry is based on several nearby stars from the 2MASS-PSC and is not corrected for the Galactic extinction. The supernova continues to rise in the J-band and is most likely near the maximum of the SN light curve. View this GCN Circular online at https://gcn.nasa.gov/circulars/44295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...