GRB 240811A: Upper limits with Mephisto

We performed simultaneous multi-band photometric observations of GRB 240811A (Page & Gupta, GCN 37136) using 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations were started ~37 min after the notice and multiple frames in uvgriz bands were acquired. The upper limits of our initial frames are the following: UTC(2024-08-11) Exptime(s) filter Mag(AB) 14:55 180 v >21.07 14:55 60 r >20.96 14:55 120 z >19.98 15:08 180 u >21.03 15:08 60 g >20.97 15:08 120 i >20.86 ---------------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. ----------------------------------------------------------------------------------