TITLE: GCN CIRCULAR NUMBER: 34840 SUBJECT: GRB 231017A: JinShan optical upper limit DATE: 23/10/19 13:18:13 GMT FROM: Dong Xu at NAOC/CAS <dxu@nao.cas.cn> D. Xu, X. Liu, S.Q. Jiang, Z.P. Zhu, S.Y. Fu, J. An, T.H. Lu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB 231017A detected by Fermi/GBM (Fermi GBM team, GCN 34822) and Swift/BAT-GUANO (DeLaunay et al. GCN 34824) using the No.2 50cm telescope (50B) located at Altay, Xinjiang, China. We obtained 20x180 s frames in the Sloan r-band, starting at 15:41:21 UT on 2023-10-17, i.e. 7.6 hr after the trigger. No optical transient is detected in our stacked image within the error region of the Swift/BAT-GUANO, with the Swift-XRT Source 2 candidate inside the error region (Dichiara et al. GCN 34829), down to a limiting magnitude of r>20.5, calibrated with the nearby PanSTARRS field. Altay Astronomical Time-Domain Project (JinShan Project for short) is located on the southern side of the Altay mountains in Xinjiang, China. It has geographical Longitude 88 43 35 E, Latitude +47 35 24 N, and Altitude 1025 meters. Altay and JinShan have the same meaning of Gold Mountain. The project consists of four 50cm telescopes with FOV of 1.7x1.7 deg^2 for each (50A, 50B, 50C, and 50D), two 100cm telescopes with FOV of 1.4x1.4 deg^2 for each (100A and 100B), and one 100cm telescope with FOV of 14x14 arcmin^2 (100C). Each telescope has different filters. JinShan is now at its early commissioning stage. View this GCN Circular online at https://gcn.nasa.gov/circulars/34840. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...