{
  "subject": "GRB 240415A: Mondy optical transient detection",
  "bibcode": "2024GCN.36118....1P",
  "submittedHow": "email-legacy",
  "circularId": 36118,
  "createdOn": 1713197754800,
  "submitter": "Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>",
  "eventId": "GRB 240415A",
  "body": "N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB-IKI-FuN:\n\nWe observed the field of GRB 240415A (Fermi GBM team, GCN 36107; Moss et al., GCN 36108, Evans et al., GCN 36109) with 1.5-meter AZT-33IK telescope of Sayan observatory at Mondy. The observations were started on 2024-04-15 (UT) 14:33:22, i.e. ~8 hr since the Fermi GBM trigger. We took 30 frames 120 s each in the R-filter. We detect a possible optical counterpart in the stacked image at coordinates of (J2000)  08:36:45.26    73:08:47.6 with uncertainties of 0.4 arcsec in both coordinates. \nPreliminary photometry of the optical source is following:\n\nDate       UT_start  MJD           Filter Exp.  OT    err  UL(3sigma)\n                    (mid, days)           (s)\n2024-04-15 14:33:22  60415.627345  R     44*120 18.84 0.08 21.9\n\nThe magnitudes were calibrated using nearby USNO-B1.0 stars.\n\n"
}