TITLE: GCN CIRCULAR NUMBER: 37291 SUBJECT: GRB 240825A: Montarrenti Observatory optical observations DATE: 24/08/25 23:40:44 GMT FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) s.leonini@iol.it
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy) and B. De Simone (Università degli Studi Di Salerno) report:
We observed the field of GRB 240825A (Swift trigger 1250617, Gupta et al., GCN 37274; Fermi/GBM trigger 746293985.085054 / 240825662, GCN 37273) with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started at 2024-08-25 21:12:38 UT (approximately 5.5 hours after burst) stacking 50x40s Rc-band CCD images.
The OT was detected at the following position:
RA (J2000.0) 22h 58m 17.26s +/-0.05 Decl. (J2000.0) +01° 01' 37.5" +/-0.13
Preliminary photometry was obtained using nearby PanSTARRS stars as follows:
MJD Filter Mag. Err. 60548.39591 Rc 19.81 +/-0.10
Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied.
Our observations are consistent with other already reported (Jiang et al., GCN 37275; Dutton et al., GCN 37276; Odeh et al., GCN 37277; Zhang et al., GCN 37278; Li et al., GCN 37280; Izzo et al., GCN 37287).
Further observations are ongoing.
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