TITLE: GCN CIRCULAR NUMBER: 38623 SUBJECT: GRB 241217A / EP241217b: Nanshan/HMT optical upper limit DATE: 24/12/18 15:03:31 GMT FROM: Zipei Zhu at NAOC zpzhu@nao.cas.cn

Z.P. Zhu, X. Liu, S.Y. Fu, J. An, S.Q. Jiang, 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 241217A/EP241217b detected by SVOM (Marius et al., GCN 38594) and Einstein Probe (Zhou et al., GCN 37492), using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 17:18:54 UT on 2024-12-17, i.e. 21.7 mins after the trigger.

The reported optical afterglow (Qiu et al., GCN 38600) is not detected in our stacked image, down to a 5-sigma limiting magnitude of ~ 18.5 mag (AB) at 0.84 hr post-burst, calibrated against G-band of Gaia DR3 and not corrected for Galactic extinction.

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