TITLE: GCN CIRCULAR NUMBER: 43499 SUBJECT: EP260119a: Mondy and SAO RAS optical upper limits DATE: 26/01/22 10:50:53 GMT FROM: Alina Volnova at IKI RAS <alinusss@gmail.com> N. Pankov (IKI), A. Moskvitin (SAO RAS), A. Volnova (IKI), O. Spiridonova (SAO RAS), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of the IKI-GRB-FuN collaboration: We observed the field of the EP260119a (Jiang et al., GCN 43447; GCN 43465; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) using the AZT-33IK telescope of the Mondy observatory starting on 2026-01-20 (UT) 18:52:22 and 2026-01-21 (UT) 19:10:23, and the Zeiss-1000 of the SAO RAS starting on 2026-01-21 (UT) 03:05:44. In the stacked frame of each observational epoch we do not detect the optical source reported previously (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin and Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek and Perley, GCN 43472; Pankov et al., GCN 43476; Jin et al., GCN 43496). Preliminary photometry and observation details are listed below: Date UT start t-T0 Exp. Filter Mag MagErr. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-01-20 18:52:22 1.80804 45x120 I n/d n/d 22.3 Mondy/AZT-33IK 2026-01-21 03:05:44 2.13449 8*300 Ic n/d n/d 21.9 SAO RAS/Zeiss-1000 2026-01-21 19:10:23 2.82417 52*120 I n/d n/d 21.7 Mondy/AZT-33IK Photometric data are based on nearby SDSS stars (I-magnitudes obtained using the 2005 Lupton transform) and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43499. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...