TITLE: GCN CIRCULAR NUMBER: 37399 SUBJECT: GRB 240905E: Nanshan/HMT optical upper limit DATE: 24/09/05 19:39:07 GMT FROM: Dong Xu at NAOC/CAS <dxu@nao.cas.cn> J. An, S.Q. Jiang, X. Liu, Z.P. Zhu, S.Y. Fu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB 240905E (Dichiara et al., GCN 37397) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 18:27:59 UT on 2024-09-05, i.e., 116 s after the Swift BAT trigger, and a series of frames were obtained without any filter. No optical source is detected in our stacked image at the Swift/XRT position (Dichiara et al., GCN 37397), down to a 5-sigma limiting magnitude of ~ 20.9 mag (AB) at 0.676 hr post-burst, calibrated against G-band of Gaia DR3 and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/37399. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...