TITLE: GCN CIRCULAR NUMBER: 42251 SUBJECT: GRB 251013C: ABObservatory optical observations DATE: 25/10/14 10:53:56 GMT FROM: A. Brosio at ABObservatory Rosarno <antonino.brosio@gmail.com> A. Brosio (ABObservatory Rosarno), M. A. Tripodi (ABObservatory Rosarno), S. Savaglio (University of Calabria), G. Bracco, P. Cianfarra, L. Sangaletti, S. Tosi & S. Zappatore (University of Genoa), S. Benatti & M. G. Guarcello (INAF Palermo), L.Cabona, M. Rainer, F. M. Zerbi, M. Basilicata (INAF Brera), D. Ricci (INAF Padova), A. Di Dato (INAF Capodimonte), S. Masiero & A. Nastasi (GAL Hassin), D. Liguori (Osservatorio "G. Galilei" Cariati), L. Betti (Osservatorio Polifunzionale del Chianti), R. Nesci (Associazione Astronomica Antares APS di Foligno), for the NOCTIS team report We observed the field of GRB 251013C, which was detected by Fermi GBM team (GCN 42221) with the 30-cm automated telescope at ABObservatory (Rosarno, Italy) in V filter. The observations began on 2025 october 13 at 20:56:53 UT, approximately 2.38 hours after the trigger. The observation consisted of 50 exposures of 120 seconds each,with good sky conditions. The mid-exposure time was 22:12:46 UT, and the final exposure ended at 23:32:52 UT. From photometry, we detect the optical counterpart in our images at the following coordinates: R.A (J2000.0) = 23 03 19.712 Dec. (J2000.0) = -00 12 53.17 From the full photometric sequence, we obtained a mean magnitude of V = 17.244 +/- 0.213 at mean JD 2460962.42529 with SNR 14.98 (AB, calibrated with the GAIA DR3 on SIMBAD). We also performed time-series photometry and obtained a light curve of the optical counterpart during our observing run and the source shows a fading trend, reaching V = 17.848 ± 0.509 at JD 2460962.47774. View this GCN Circular online at https://gcn.nasa.gov/circulars/42251. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...