{
  "createdOn": 1792563444464,
  "eventType": [
    "X-ray Transient",
    "Optical Transient"
  ],
  "format": "text/plain",
  "body": "N. Pankov (IKI),  M. Krugov (FAI), A. Pozanenko (IKI), A. Moskvitin (SAO RAS), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:\n\nWe observed the field of the Einstein Probe fast X-ray transient EP261015a (Li et al., GCN 45956) with the 1.5-m AZT-20 telescope of the Assy-Turgen Observatory. Observations started on 2026-10-19 at 19:20:07 UT, 4.276 days after the EP/WXT trigger. A series of  frames was obtained in the r' filter.\n\nWe clearly detect the optical counterpart (Corcoran et al., GCNs 45955 and 45972; Li et al., GCNs 45956 and 45969; Méndez et al., GCN 45960; Ma et al., GCN 45963; Mohan et al., GCN 45967; Fortin et al., GCN 45991;  Volnova et al., GCN 45997; Pawar et al., GCN 45998; Shivaprasad et al., GCN 46000) at coordinates (J2000) 02:57:19.83, -13:21:17.3. The residual source is detected after subtraction of a DESI Legacy Survey DR10 r-band template. Preliminary photometry of the residual source is given below.\n\nDate        UTstart t-T0        Exp.  Filter OT    Err. UL\n                    (mid, days) (s)                     (3sigma)\n2026-10-19 19:20:07 4.2764      67*60 r'     22.59 0.06 23.8\n\nThe photometry was calibrated against nearby Pan-STARRS1 stars\n\nRA (J2000) Dec (J2000) r\n02:57:33.73 -13:21:44.6 16.891\n02:57:25.43 -13:24:41.2 19.263\n\nand is not corrected for Galactic extinction.\n\nThe residual magnitude is consistent with the Legacy Survey-subtracted measurements of Fortin et al. (GCN 45991; r = 22.58 +/- 0.09 at 3.7 d) and Shivaprasad et al. (GCN 46000; r = 22.52 +/- 0.28 at 4.37 d).",
  "eventId": "EP261015a",
  "circularId": 46003,
  "submitter": "Nicolai Pankov at IKI <colinsergesen@gmail.com>",
  "subject": "EP261015a:  AZT-20 Assy-Turgen optical observations",
  "submittedHow": "web"
}