{
  "subject": "EP260329b: Mondy and Assy-Turgen optical upper limits",
  "createdOn": 1775035528469,
  "bibcode": "2026GCN.44173....1V",
  "eventId": "EP260329b",
  "submittedHow": "email",
  "body": "A. Volnova (IKI), E. Klunko (ISTP), D. Anarbek (FAI), M. Krugov (FAI), A.\nPozanenko (IKI), N. Pankov (IKI) report on behalf of IKI-GRB-FuN:\n\nWe observed the field of the fast X-ray transient EP260329b (Song et al.,\nGCN 44142; EP Team, GCN 44155) with the AZT-33IK 1.5m telescope of the\nSayan Solar Observatory (Mondy) taking several 40-second expositions in\nR-band, and with the AZT-20 telescope of Assy-Turgen observatory taking\nseveral 30-second exposures in r' filter on Mar. 29. In the stacked frames\nwe do not detect the optical counterpart reported previously (Li et al.,\nGCN 44139; Zhu et al., GCN 44140; Eyles-Ferris et al., GCN 44144; Aryan et\nal., GCN 44147; Lipunov et al., GCN 44150; Mo et al., GCN 44163; O'Neill et\nal., GCN 44169).\nPreliminary photometry and observational details are the following:\n\nDate        UT start  t-T0      Exp.    Filter Obj.   Err.  UL\n Site/Telescope\n                     (mid,days) (n*s)                      (3sigma)\n2026-03-29  15:24:19  0.22110   90*40   R      n/d    n/d   21.1\n Mondy/AZT-33IK\n2026-03-29  19:57:04  0.40444   80*30   r      n/d    n/d   21.6\n Assy-Turgen/AZT-20\n\nThe photometry is based on several nearby stars from the SDSS-DR16\ncatalogue (Lupton transformations were used for the R-band values) and is\nnot corrected for the Galactic extinction.\n",
  "submitter": "Alina Volnova at IKI RAS <alinusss@gmail.com>",
  "circularId": 44173
}