X-ray Fluxes from the Swift X-ray Telescope Point Source Catalog
When an object is not listed in the XMM-Newton Serendipitous Survey
catalog, I then consulted the Swift XRT point source catalog
(2SXPS; see
Evans
et al.). This catalog reports 0.3-10 keV fluxes based on power-law and
thermal plasma model fits; for most IPs, the former usually provides a
better phenomenological fit (presumably because of the complex
absorber usually present in the X-ray spectra of IPs), so that value is
adopted for the purpose of the IP catalog.
However, if I know that the Swift observations were taken mostly during
nova eruptions or dwarf nova outbursts, then I do not use the 2SXPS fluxes,
since the intent is to list a typical X-ray flux during normal accretion-powered
phase of each IP or candidate.