GCN Circular 40383
Subject
EP#01709175213/IGR J19566+0326: Swift-XRT detection
Date
2025-05-07T14:44:00Z (a year ago)
From
Maia Williams at PSU <mjw6837@psu.edu>
Via
Web form
M.A. Williams (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
We have analyzed 1100 s of XRT data for the recently reported Einstein Probe (EP) trigger 01709175213 (GCN #40375), from T0+2.8 ks to T0+9.1 ks after detection by EP-WXT. The data are entirely in Photon Counting (PC) mode.
We detect an X-ray source within the estimated 90% C.L. EP-WXT error region. Using 1135 s of XRT PC mode data and 2 UVOT images, we find an enhanced XRT position: RA, Dec = 299.16259, 3.44549 which is equivalent to:
RA (J2000): 19h 56m 39.02s
Dec (J2000): +03° 26′ 43.8′′
with an uncertainty of 2.5 arcsec (radius, 90% confidence).
This position is 46 arcsec from the EP-WXT position, and consistent with the X-ray source found in EP-FXT data. As noted by Sun et al. (GCN #40375), this position is consistent with the LMXB IGR J19566+0326/MAXI J1957+032.
The source has a peak count rate of 14.76 (±0.23) ct/s (0.3-10 keV). The mean count rate from the LSXPS catalogue is 0.1240 (±0.0019) ct/s, suggesting this source is an outburst of IGR J19566+0326.
The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/EP/EP_FIELD00037/.