GCN Circular 38430
Subject
EP241201a: EP-FXT follow-up observations
Date
2024-12-03T15:57:18Z (4 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
W. Chen (NAO, CAS), G. Y. Zhao (SYSU), C. Zhou (HUST), T. Zhao (NAO, CAS), W. D. Zhang (NAO, CAS) report on behalf of the Einstein Probe team:
Following the detection of the fast X-ray transient EP241201a (Chen et al., GCN 38415), we performed an observation with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe mission. The observation started at 2024-12-02T09:23:55 (UTC), about 12 hours after the EP-WXT detection, with an exposure time of 2.9 ks. Within the WXT error circle, an uncatalogued X-ray source is detected at R.A. = 282.4865 deg, DEC = 66.0693 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The average FXT spectrum in 0.5-10 keV can be fitted by an absorbed power law with a photon index of 4.8(-1.5,+1.7) and a column density of 1.2(-0.5,+0.6) x 10^22 cm^-2, giving an average unabsorbed flux of 2.9(-2.0, +14.4) x 10^-12 erg/s/cm^2 in the 0.5-10 keV band. Compared to the WXT detection, its flux has droped by about three orders of magnitude. The X-ray spectrum in 0.5-10 keV can also be fittted by an absorbed black body with a temperature of 0.27(-0.06, +0.08) keV and a column density of 4.9(-3.2, +4.0) x 10^21 cm^-2, giving an average unabsorbed flux of 3.9(-1.5, +3.7) x 10^-13 erg/s/cm^2.
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).