TITLE: GCN CIRCULAR NUMBER: 36067 SUBJECT: GRB 240411B: OHP/T193 optical observations DATE: 24/04/12 05:38:40 GMT FROM: Benjamin Schneider at MIT <bschn@mit.edu> B. Schneider (MIT), C. Adami (LAM/Pytheas/AMU), E. Le Floc’h (CEA Paris-Saclay), A. Saccardi (GEPI/Obs. de Paris) report on behalf of a larger collaboration: We observed the field of the GRB 240411B (Parsotan et al., GCN 36063; Goad et al., GCN 36065) and its afterglow candidate (Izzo et al., GCN 36064) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. A total of 10 exposures (8x600s + 2x720s) were obtained in the r-band at 00:44:01.5 UT on 2024-04-12 (~9.2h after the trigger). In the combined frame, we detect a source consistent with the optical afterglow reported by Izzo et al. (GCN 36064). The preliminary magnitude derived for that source is r = 23.1 +/- 0.3 mag (AB) The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular Jean-Pierre Troncin for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/36067. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...