{
  "editedOn": 1776958560146,
  "circularId": 44398,
  "eventId": "EP260416a",
  "submittedHow": "web",
  "version": 2,
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Alina Volnova at IKI RAS <alinusss@gmail.com>",
  "subject": "EP260416a: Mondy optical observations",
  "createdOn": 1776947952048,
  "format": "text/plain",
  "submitter": "Alina Volnova at IKI RAS <alinusss@gmail.com>",
  "body": "A. Volnova (IKI),  A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (IKI)  report on behalf of IKI-GRB-FuN:\n\nWe observed the field of the fast X-ray transient EP260416a (Hu et al., GCN 44307, 44324) at z = 1.909 (He et al., GCN 44336; An et al., GCN 44339) with the AZT-33IK 1.5m telescope of the Mondy observatory  starting on 2026-04-21 (UT) 15:28:28 and taking several 120-seconds frames in the R band. The optical counterpart (Ducoin et al., GCN 44310; Li et al., GCN 44315; Hua et al., GCN 44318; Lee et al., GCN 44319; Zheng et al., GCN 44321; Martin-Carrillo et al., GCN 44328; Li et al., GCN 44334; He et al., GCN 44336; An et al., GCN 44339; Jelinek et al., GCN 44341; Guziy et al., GCN 44351; Ho et al., GCN 44354; Pawar et al., GCN 44373; Li et al., GCN 44376; Moskvitin et al., GCN 44395) is clearly detected in the stacked frame.\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)\n2026-04-21  15:28:28  5.43677   27*120  R      22.72  0.09  23.3    Mondy/AZT-33IK\n\nThe photometry is based on nearby USNO-B1.0 stars (R2-magnitudes) and is not corrected for Galactic extinction."
}