TITLE: GCN CIRCULAR NUMBER: 36074 SUBJECT: GRB 240411B: HiPERCAM/GTC observation DATE: 24/04/12 19:07:20 GMT FROM: Antonio de Ugarte Postigo at OCA <deugarte@oca.eu> A. de Ugarte Postigo (CNRS, OCA, LAM), N. R. Tanvir (U. Leicester), J. F. Agui Fernandez (CAHA), A. Martin-Carrillo (UCD), C. C. Thoene (ASU-CAS), L. Izzo (INAF-OACn & DARK/NBI), J. P. U. Fynbo (DAWN/NBI), G. Lombardi (GRANTECAN), S. Geier (GRANTECAN) report: We observed the field of GRB 240411B (Parsotan et al. GCN 36063) with HiPERCAM on the 10.4m GTC, at the Roque de Los Muchachos Observatory (Spain). We simultaneously obtained 20x60s exposure in each of the u, g, r, i, and z filters. The transparency was bad due to strong calima and the seeing was also poor. The afterglow (Izzo et al. 36064; Goad et al. GCN 36065; Schneider et al. GCN 36067; Ror et al. GCN 36069) is well detected in g, r, i and z, but not in u-band, where the limit is shallow. Observations had a mean time of 0.4256 days after the burst. We measure an r-band magnitude (AB) of r = 23.21+/- 0.08 mag as compared with field star magnitudes from the SDSS. View this GCN Circular online at https://gcn.nasa.gov/circulars/36074. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...