EP250706a
GCN Circular 41005
Subject
EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
Date
2025-07-07T09:25:55Z (a day ago)
Edited On
2025-07-07T13:29:58Z (a day ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Q. C. Liu (THU), J. W. Hu, D. Y. Li, B. B. Zhang (NAO,CAS), Y. H. Cheng (YNU), P. Y. Han (HUST), W. Yuan (NAO,CAS) on behalf of the Einstein Probe team
We report on the detection of a fast X-ray transient, designated EP250706a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event started at 2025-07-06T15:48:25 (UTC). The position of the source is R.A. = 284.02 deg, DEC = 32.329 deg (J2000) with an uncertainty of 2.2 arcmin in radius (90% C.L. statistical and systematic). The trigger time and position of this X-ray transient are consistent with that of GRB 250706A (GCN 40988, GCN 40990, GCN 40998, GCN 41000, GCN 41001).
The transient event lasts for more than 250 seconds. No automated follow-up X-ray observation was performed due to that EP was performing a ToO observation of higher priority. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 2.7 (+1.2/-1.0) with a column density value of 0.7 (+0.4/-0.3) x 10^22 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 0.8 (+1.0/-0.3) x 10^-9 erg/s/cm^2. The peak flux is around 4.6 x 10^-9 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
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).