TITLE: GCN CIRCULAR NUMBER: 40672 SUBJECT: GRB 250610B : SVOM/GWAC-F60A and F50 observations DATE: 25/06/10 18:53:15 GMT FROM: Weikang Zheng at UC Berkeley weikang@berkeley.edu

J. Wang, W. L. Dong, L. P. Xin(NAOC), L. J. Chen(GXU), Y. G. Yang(HNU), X. H. Han, C. WU, Y. L. Qiu, H. L. Li, X .M. Lu, R. S. Zhang, Y. Xu, L. Huang, H. B. Cai, Y. J. Xiao, P. P. Zhang, L. Lan, W. J. Xie, Z. H. Yao, J. Y. Wei(NAOC), X. G. Wang, E. W. Liang(GXU) and W. Zheng (UCB) report on behalf of the SVOM follow-up team:

We observed the field of SVOM GRB 250610B (Saccardi et al., GCN 40671) with the GWAC-F60A and GWAC-F50 at Xinglong Observatory, China. F60A started observing at 2025-06-10T17:14:17.39 UTC with a set of 34 images in R-band. F50 started observing at 2025-06-10T17:14:17.39 UTC and with a set of 9 images in R-band.

After coadding the images, we do not find any uncatalog candidate within the SVOM/ECLAIRs error box. We estimate the upper limit of 16.0 mag for GWAC-F60A at mid time of 54.5 minutes after brust, and upper limit of 17.5 mag for GWAC-F50 at mid time of 54.0 minutes after brust.

Two 60cm GWAC-F60(A/B) are operated by Guangxi University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 19*19 arcmin. The 50cm telescope (F50A) is operated by Huaibei Normal University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 27*27 arcmin.

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