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.