GCN Circular 41740
Subject
EP250905b: EP-FXT follow-up observation
Event
Date
2025-09-06T15:00:37Z (3 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
X. Mao (NAO,CAS), Q. C. Liu (THU), Y. H. Cheng (SWIFAR,YNU), G. J. Yang, Y. Liu (NAO,CAS) on behalf of the Einstein Probe team:
EP-FXT performed a follow-up observation of EP250905b (GCN 41735) at 2025-09-06T05:05:21 (UTC), about 10 hours after the WXT detection, with an exposure time of 3.2 ks. FXT detected a weak uncatalogued source within the WXT error circle at R.A. = 90.7297, DEC = -54.1582 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). Assuming a powerlaw spectrum with the absorption fixed at the Galactic value of 7.64x10^20 cm^-2 and the photon index of 2, the flux in 0.5-10 keV is derived to be approximately 2x10^-14 erg/s/cm2 from the FXT count rate.
Further follow-up observations are encouraged to identify the nature of this source.
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).