TITLE: GCN CIRCULAR NUMBER: 41311 SUBJECT: EP250807a: EP-FXT follow-up observation upper limit DATE: 25/08/10 04:22:40 GMT FROM: EP Team at NAOC/CAS ep_ta@bao.ac.cn

Y. Wang (PMO, CAS), Y. Q. Zhao (USTC,PRIC), H. Q. Cheng, Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team:

EP-FXT performed a follow-up observation of EP250807a (Wang et al. GCN 41277) at 2025-08-08 10:27:06 (UTC), about 11 hours after WXT trigger, with an exposure time of 2972 s. No significant X-ray source was detected by the FXT within the WXT error circle, the flux upper limit is 7.4e-14 erg/cm^2/s in the 0.5-10 keV.

Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).

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