TITLE: GCN CIRCULAR NUMBER: 40226 SUBJECT: GRB 250424A: DDOTI Afterglow Detection DATE: 25/04/24 08:30:40 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it> Rosa L. Becerra (U Roma), Sahil Atri (U Roma), Alan M. Watson (UNAM), Eleonora Troja (U Roma), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM) and Margarita Pereyra (UNAM) report: We observed the field of the GRB 250424A detected by Swift/BAT (Cenko et al., GCN Circ. 40136) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-04-24 UTC from 07:23 UTC to 7:45 UTC (from T+30.6 h to T+53.5 min after the trigger) and obtained a total exposure of 20 minutes. Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect a source consistent with the UVOT position (Cenko et al., GCN Circ. 40136) and the previous optical detections (Francile et al., GCN Circ. 40222, Brivio et al., GCN Circ. 40225), with an AB magnitude of: w = 19.4 +/- 0.1 Further observations and analysis are ongoing. This value is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/40226. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...