{
  "circularId": 45537,
  "body": "N. Pankov (IKI), E. Klunko (ISTP), A. Pozanenko (IKI),\nA. Volnova (IKI), A. Moskvitin (SAO RAS) report on behalf of IKI-GRB-FuN:\n\nWe observed the field of GRB 260909A discovered by SVOM\n(Saccardi et al., GCN 45534), and observed in optical by COLIBRI \n(Guan et al., GCN 45535) and Xinglong (Ma et al., GCN 45536), which resulted in upper limits. The observations were carried out using the 1.6-meter AZT-33IK telescope of Sayan Solar Observatory (Mondy) equipped with a CMOS photometer. A set of 38x120 sec images in the R band was obtained starting on 2026-09-09 at 13:44 UT (i.e. 2.446 hours since trigger).\n\nIn the coadd image we detect an uncatalogued object at coordinates (J2000) RA=00 52 08.462, Dec=+24 11 30.93 with a statistical uncertainty of 0.37 arcsec (66.7%).\nThe observation details and preliminary photometry is as follows:\n\nDate,      UTstart  t-T0       Exp.  Filter Mag     Err.     UL\n                    (mid,d)    (n*s)                       (3-sigma)\n\n2026-09-09 13:44:47 0.12831  38*120  R      21.6    0.1      22.7\n\nThe preliminary photometry (Vega) is based on nearby USNO-B1.0 stars\nand not corrected for the Galactic extinction. We suggest \nthis uncatalogued source to be the GRB 260909A afterglow. We \nencourage further photometric follow-up of the SVOM/MXT field to verify \nthis candidate source.\n",
  "eventId": "GRB 260909A",
  "format": "text/plain",
  "subject": "GRB 260909A: Mondy optical observations and afterglow candidate",
  "eventType": [
    "GRB",
    "Afterglow",
    "Optical Transient"
  ],
  "createdOn": 1788970441615,
  "submittedHow": "web",
  "submitter": "Nicolai Pankov at IKI <colinsergesen@gmail.com>",
  "bibcode": "2026GCN.45537....1P"
}