{
  "subject": "EP260321a: CMO SAI J,K observations",
  "submittedHow": "web",
  "circularId": 44295,
  "createdOn": 1776166049301,
  "eventId": "EP260321a",
  "submitter": "Alina Volnova at IKI RAS <alinusss@gmail.com>",
  "format": "text/plain",
  "body": "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:\n\nWe 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.\n\nPreliminary photometry and observational details are the following:\n\nDate       UT_start t-T0       Exp.   Filter Obj.  Err. UL       Site/Telescope\n                    (mid,days) (n*s)                   (3sigma)\n2026-04-02 21:11:47 12.36569   6*96   J      16.76 0.04 20.5     CMO SAI/SAI-2.5\n2026-04-02 20:58:27 12.35698   20*29  K      16.50 0.06 19.1     CMO SAI/SAI-2.5\n2026-04-07 17:53:10 17.23089   11*96  J      16.45 0.04 21.1     CMO SAI/SAI-2.5\n\nThe photometry is based on several nearby stars from the 2MASS-PSC and is not corrected for the Galactic extinction.\n\nThe supernova continues to rise in the J-band and is most likely near the maximum of the SN light curve.",
  "bibcode": "2026GCN.44295....1V"
}