GCN Circular 44067
Subject
GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
Event
Date
2026-03-21T11:45:32Z (14 days ago)
From
A. Brosio at ABObservatory Rosarno <antonino.brosio@gmail.com>
Via
Web form
A. Brosio (ABObservatory Rosarno), M. A. Tripodi (ABObservatory Rosarno), S. Savaglio (Università della Calabria), S. Benatti (INAF - Osservatorio Astronomico di Palermo), M. Basilicata, M. Rainer (INAF - Osservatorio Astronomico di Brera), S. Tosi (Università di Genova), A. Di Dato (INAF - Osservatorio Astronomico di Capodimonte), D. Liguori (Osservatorio "G. Galilei", Liceo Scientifico Cariati), A. Nastasi (GAL Hassin, Isnello), E. Pace, R. Stanga, L. Betti (Università di Firenze - Osservatorio Polifunzionale del Chianti), D. Ricci (INAF - Osservatorio Astronomico di Padova) and the NOCTIS Collaboration report:
We observed the optical counterpart of GRB 260310A / AT 2026FGK, previously reported by several groups as the optical afterglow:
(O'Neill et al. 2026, TNS Discovery Report 294132; Konno et al., GCN 43974; Hinds et al., GCN 43977; Lipunov et al., GCN 43978; Martin-Carrillo et al., GCN 43979; M éndez 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; Jayaraman et al., GCN 43994; Stein et al., GCN 43996; Martin-Carrillo et al., GCN 44000; Watson et al., GCN 44001; Lai et al., GCN 44002; Izzo et al., GCN 44003; Brivio et al., GCN 44004; Moskvitin et al., GCN 44006; Romanov, GCN 44020; Pawar et al., GCN 44022; Belkin et al., GCN 44043; Li et al., GCN 44044; Gupta et al., GCN 44051; Salunke et al., GCN 43958; Becerra et al., GCN 44059; Volnova et al., GCN 44060; Busmann et al., GCN 44061).
At JD 2461120.34019 (2026-03-20.84019 UT), we measured the source at:
AT 2026FGK 18.92 +/- 0.10 Sloan r
Photometric calibration was performed using the APASS catalog, adopting the comparison stars at coordinates
RA(J2000) = 219.274765, Dec(J2000) = +71.914946;
RA(J2000) = 219.311345, Dec(J2000) = +71.880330.