GCN Circular 44004
Subject
GRB 260310A / AT2026fgk: TNG NIR detection
Event
Date
2026-03-14T14:48:10Z (2 days ago)
From
Riccardo Brivio at INAF-OAB <riccardo.brivio@inaf.it>
Via
Web form
R. Brivio (INAF-OAB), D. Malesani (DAWN/NBI and Radboud), L. Izzo (INAF-OACn and DARK/NBI), P. D’Avanzo (INAF-OAB), V. D’Elia (ASI-SSDC), A. Melandri (INAF-OAR), A. Rossi (INAF-OAS), M. de Pasquale (Univ. Messina), Aldo Fiorenzano (INAF-TNG), Carmen Padilla (INAF-TNG) report on behalf of the CIBO collaboration:
We observed the likely counterpart of GRB 260310A, detected by Fermi/GBM (Fermi GBM team, GCN 43951; Hamburg & Meagan, GCNC 43975) and AstroSat CZTI (Salunke et al., GCN 43958) with the Italian 3.6m TNG telescope equipped with the near-infrared camera NICS. A series of images was obtained with the J and H filters starting on 2026 March 14 at 05:11:46 UT (i.e. 96.2 hours after the burst), and lasted 40 minutes for each filter.
The optical/NIR counterpart, also reported as AT2026fgk (Konno et al., GCN 43974; Hinds et al., GCN 43977; Lipunov et al., GCN 43978; Martin-Carrillo et al., GCN 43979; Moreno Méndez et al., GCN 43980; de Ugarte Postigo et al., GCN 43984; Hsu et al., GCN 43986; Pursiainen et al., GCN 43990; Becerra et al., GCN 43991; Li et al., GCN 43993; Stein et al, GCN 43996; Martin-Carrillo et al., GCN 44000; Watson et al., GCN 44001; Lai et al., GCN 44002; L. Izzo, GCN 44003) is detected in the co-added images with the following magnitudes:
J = 17.0 +/- 0.1 (Vega, calibrated against the 2MASS catalogue),
at a mid-time of 96.5 hr after the trigger;
H = 15.9 +/- 0.1 (Vega, calibrated against the 2MASS catalogue),
at a mid-time of 97.1 hr after the trigger.