Extended Data Fig. 2: Monte Carlo aperture photometry.
From: A white dwarf accreting planetary material determined from X-ray observations
a, c, The blue points show the positions of the approximately 100,000 test apertures, each 1 arcsec in radius, used to sample 100 arcsec around the target. The absolute number of test apertures, after removing those that fell within a masked region, is shown in the panels. The sky coordinates of all recorded events that fall within a masked region are shown in orange. b, d, The normalized histogram shows the fraction of test apertures with event counts equal to or greater than that of a given bin. The Monte Carlo was performed on the soft (a, b) and soft + medium (c, d) bands. The soft band analysis has 0.001% of test apertures returning four counts, enableing us to rule out chance alignment at 4.4σ.
