GRB 240811A: Bassano Bresciano Observatory upper limit

We imaged the field of GRB 240811A detected by SWIFT(trigger 1248132) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy. The observations started 5.56 hour after the GRB trigger, At the end of twilight with our Newton telescope D=450 mm F/D=4.5. Weather conditions were good. We co-added 150 exposures of 20 sec each (total 50 min). Start T0+ End T0+ Vlim 5.56 hour 6.47 hour 21 We did not found any optical counterpart in the error box of the XRTcandidate (K. L. Page & R. Gupta, GCN 37136; v. Lipunov et al., GCN 37137; Guowang Du et al., GCN 37140; A.P. Beardmore et al., GCN 37141; R. Strausbaugh and A. Cucchiara, GCN 37142; N. P. M. Kuin and K. L. Page, GCN 37147; T. Sbarrato et al., GCN 37149). Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction. Reference: http://www.osservatoriobassano.org/grb.asp The message may be cited.