TITLE: GCN CIRCULAR NUMBER: 40397 SUBJECT: GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation. DATE: 25/05/08 14:26:33 GMT FROM: Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy <giovannicalapai@tiscali.it> Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. Report: we observed the field of GRB 250502A detected by SVOM/ECLAIRs (Wang et al. GCN 40313) with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. The observations were started at 2025-05-02 21:24 UT (approximately 12.62 hours after burst) stacking a set of unfiltered CCD image. The observations were carried out with clear skies and good visibility conditions. We detected a very faint object at the following position: RA (J2000.0) 13h 46m 05.62s Decl. (J2000.0) -10° 45' 32.3" Photometry was obtained using nearby PanSTARRS stars as follows: Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Mag. err. 2025-05-02 23:44:41 UT 14.97 200x60s CR 20.70 +/-0.16 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 Rakotondrainibe et al. GCN 40315; An et al. GCN 40319; Li et al. GCN 40320; Ghosh et al. GCN 40322; de Ugarte Postigo et al. GCN 40328; Pérez-Fournon et al. GCN 40330; Odeh et al. GCN 40331; Bochenek & Perley GCN 40333; Corcoran et al. GCN 40334; Leonini et al. GCN 40337; Zheng et al. GCN 40338; Pankov et al. GCN 40339; Brivio et al. GCN 40349; Quadri et al. GCN 40370. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40397. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...