TITLE: GCN CIRCULAR NUMBER: 37050 SUBJECT: GRB 240805B: JinShan optical upper limits DATE: 24/08/05 17:34:05 GMT FROM: Zipei Zhu at NAOC zpzhu@nao.cas.cn

Z.P. Zhu, X. Liu, J. An, S.Y. Fu, S.Q. Jiang, L.B. He, D. Xu (NAOC) report on behalf of a large collaboration:

We observed the field of GRB 240805B detected by Swift/BAT (Williams et al., GCN 37043), using the JinShan 100cm-C telescope (100C) and 50cm-D telescope (50D) located at Altay, Xinjiang, China.The observation started at 14:55:19 UT on 2024-08-05, ~ 0.44 hr after the BAT trigger. A series of exposures were obtained in the Sloan g-, r-, i-, and z- filters.

No uncataloged source is found within or around the XRT error circle (Williams et al., GCN 37043). The obtained upper limits are as follows: Telescope Tmid-T0/hr Filter Exptime Mag(AB) 100C 0.582 r 5x200s >22.0 100C 0.868 i 5x200s >22.2 100C 1.318 z 7x300s >21.5 50D 1.683 g 20x180s >22.0

We acknowledge the excellent support from S.W. Luo, M.M. Yang, Z.K. Feng, Q.C. Zhao and L.F. Huo for enabling these observations.

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