TITLE: GCN CIRCULAR NUMBER: 43570 SUBJECT: EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits DATE: 26/01/30 14:23:44 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), J. An (NAOC), G. Corcoran (UCD), P. D’Avanzo (INAF/OAB), M. De Pasquale (U. Messina), L.B. He (NAOC), A. Martin-Carrillo (UCD), A. Melandri (INAF/OAR), D. Xu (NAOC), W. Boschin (TNG), V. Lorenzi (TNG), H. Lucio Medeiros (TNG), T. Pursimo (NOT), report on behalf of a larger collaboration: We observed the optical counterpart (He et al., GCN 43555) of the high-energy transient EP260128a / GRB 260128A (Zhou et al., GCN 43549; Ravasio et al., GCN 43556) in both the optical and infrared. Optical observations were carried out at the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera, for a total of 14x200 s in the SDSS z filter. NIR observations were carried out at the Telescopio Nazionale Galileo (TNG) equipped with the NICS camera, for a total of 40x60 s in the J filter. The afterglow (He et al., GCN 43555) is not detected in any of our stacked images. We report 3-sigma limiting magnitudes: z > 23.2, mean epoch 2026 Jan 29.961 UT (23.39 hr after the EP trigger); J > 22.0, mean epoch 2026 Jan 29.939 UT (22.88 hr after the EP trigger). The above magnitudes are in the AB system, are calibrated against nearby objects from the Pan-STARRS (z) and VHS (J) catalogs, and are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43570. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...