TITLE: GCN CIRCULAR NUMBER: 41001 SUBJECT: GRB 250706A: JinShan optical upper limits DATE: 25/07/07 07:17:13 GMT FROM: Zipei Zhu at NAOC <zpzhu@nao.cas.cn> Z.P. Zhu, S.Q. Jiang, X. Liu, J. An, L.B. He, D. Xu (NAOC), S.Y. Fu(HUST), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB250706A detected by Swift/BAT (Moss et al., GCN 40988), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations began at 15:55:19 UT on 2025-07-06, i.e., 6.8 minutes after the BAT trigger, and a series of frames were obtained in the Sloan r- and z-band. No new optical source is detected within the XRT error circle (Moss et al., GCN 40988), consistent with the reported results (Mohan et al., GCN 40990; Wu et al., GCN 40998), down to 5-sigma upper limits of r ~ 21.4 and z ~21.1, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction. We acknowledge the excellent support from T.Q. Chen for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41001. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...