{
  "submittedHow": "web",
  "circularId": 44103,
  "submitter": "Nicolai Pankov at IKI <colinsergesen@gmail.com>",
  "body": "N. Pankov (IKI), A. Pozanenko (IKI), E. Shekotikhin (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of IKI-GRB-Fun collaboration:\n\nWe observed the localization of the EP260321A (Huang et. al, GCN 44068) with the AZT-33IK telescope of the Mondy observatory. We obtained series in the R filter on epochs 2026-03-21, 2026-03-22 and 2026-03-23. The source reported by the Kinder (Lee et al., GCN 44070) and observed till now by (Aryan et al., GCN 44081; Ma et al., GCN 44074;  Aguilar-Ruiz et al., GCN 44076; Liang et al., GCN 44079; Aryan et al., GCN 44081; Tanvir et al., GCN 44082; Moran et al., GCN 44083; Ahumada et al., GCN  44084; Liu et al., GCN 44087; Sankar et al., GCN 44089; de Ugarte Postigo et al., GCN 44091; Xu et al., GCN 44092) is clearly visible in the co-add images on all epochs. The early brightening of the source is evident after subtracting the epochs (i.e., 2026-03-23 minus 2026-03-22). \n\nThe photometry of the host galaxy + the source and observation details are listed below:\n\nDate       UT start  t-T0         Exp.   Filter OT+host Err.  UL(3sigma)\n                     (mid, days)  (s)\n2026-03-21 14:50:00  0.11785      30x120   R     18.09  0.02  22.7\n2026-03-22 16:02:29  1.16819      30x120   R     17.77  0.02  22.7\n2026-03-23 14:48:46  2.11561      28x120   R     17.29  0.02  22.8\n\nThe photometry was calibrated using nearby USNO-B1.0 stars (R2 mags) and has not been corrected for the Galactic extinction. The photometry of the 2026-03-23 epoch might be affected by the host very slightly, while for other epochs the photometry is significantly contaminated by the host.",
  "createdOn": 1774355673163,
  "format": "text/plain",
  "subject": "EP260321A: Mondy optical observations",
  "eventId": "EP260321a",
  "bibcode": "2026GCN.44103....1P"
}