TITLE: GCN CIRCULAR NUMBER: 40926 SUBJECT: GRB 250702F: Leavitt Observatory optical observations DATE: 25/07/03 18:42:20 GMT FROM: leavittob@gmail.com L. Moretti, E. Pavoni (Leavitt Observatory, Italy) Members of: GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani ATA - Associazione Tuscolana di Astronomia In a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report: We observed the field of GRB 250702F detected by Fermi-GBM (GCN 40892) and Swift/UVOT (Klingler et al., GCN 40894), using our Ritchey-Chrétien telescope (D=250 mm, F/D=8). The observations began approximately 0.5 hours after the trigger, ending at 2025-07-02T23:59:57 UT, stacking a set of CCD images of 180 seconds each, with good weather conditions. All images were processed by a single data processing pipeline based on astropy package (Astropy Collaboration et al., 2022ApJ...935..167A). The optical afterglow reported by Jelinek et al. (GCN 40895), Kumar et al. (GCN 40896), Lipunov et al. (GCN 40899), Martin-Carrillo et al. (GCN 40900), de Ugarte Postigo et al. (GCN 40901), Angulo et al. (GCN 40907), Becerra et al. (GCN 40911), Brivio et al. (GCN 40913), An et al. (GCN 40916), Dutton et al. (GCN 40921) was clearly detected at the following coordinates: RA (J2000) = 14:11:44.65 Dec(J2000) = +16:44:54.59 with the following photometry: Date UT at mid-exposure Exposure Filter Mag. Mag. err. 2025-07-02 21:38:43 UT 4x180s CR 17.33 +/-0.21 2025-07-02 21:52:08 UT 4x180s CR 17.72 +/-0.21 2025-07-02 22:05:47 UT 5x180s CR 17.96 +/-0.21 2025-07-02 22:19:44 UT 4x180s R 18.13 +/-0.25 2025-07-02 22:31:52 UT 4x180s R 17.80 +/-0.21 2025-07-02 22:44:01 UT 4x180s R 18.02 +/-0.25 2025-07-02 22:59:11 UT 5x180s R 18.30 +/-0.21 2025-07-02 23:17:29 UT 4x180s R 18.80 +/-0.25 2025-07-02 23:29:38 UT 4x180s R 19.00 +/-0.25 2025-07-02 23:47:50 UT 8x180s R 19.30 +/-0.21 CR magnitude is unfiltered with R zero point. R is Rc filter in Johnson-Cousins system. Magnitude was calibrated with the Pan-STARRS cat. and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction. This message may be cited. Reference: https://leavittobservatory.altervista.org View this GCN Circular online at https://gcn.nasa.gov/circulars/40926. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...