TITLE: GCN CIRCULAR NUMBER: 41716 SUBJECT: The EP-WXT trigger 01709201259: a brightening of LMXB 1ES 1735-26.9 DATE: 25/09/05 07:07:13 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> R. D. Liang (NAOC), Y. Wang (PMO), Y.H.Cheng (SWIFAR,YNU), W. D. Zhang (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of X-ray brightening of Low Mass X-ray Binary (LMXB) 1ES 1735-26.9 by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The burst triggered EP-WXT (ID: 01709201259) at the time of 2025-09-05T05:11:45 UTC. The WXT position of the source is R.A. = 264.569 deg, DEC = -26.997 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The estimated flux in the 0.5-4 keV band is around 5 x 10^-10 erg/cm^2/s, which is an order of magnitude higher than the previous detection. A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. An X-ray source was detected at R.A. = 264.5679 deg, DEC = -26.9927 (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic), which is consistent with the position of known LMXB 1ES 1735-26.9. The estimated flux in the 0.5-10 keV band is around 2 x 10^-10 erg/cm^2/s. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/41716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...