Cen continuum SED and comparison with theoretical models. Top panel: Cen fiducial reference spectrum 4 from night 1 (solid black line) and the fiducial spectrum 8 from night 2 (dotted gray line). Both have been corrected for reddening. The solid orange line represents a power law of power −7/3, as predicted for steady state accretion disks; all the other colored lines are stellar atmosphere models. Their temperatures and gravities are marked in the figure itself (shade of blues for the Koester WD models; shades of green for the Tubingen database stellar atmospheres; shades of red for the Next Generation NLTE cool stars models). Bottom panel: fiducial reference spectrum 4 from night 1 together with the Swift UVOT photometry (filled black circle for the April 2019 observation; open magenta squares for the June 2019 observations), the Chandra spectrum, the same models as in the top panel, and a T = 50 kK log g = 7.0 model with solar abundances (magenta line; Tubingen database).