Gaia Hertzsprung-Russell diagram for sources with distance estimates. The x-axis shows the Gaia BP-RP color, and the y-axis shows the absolute G-band magnitude. The color bar indicates the unabsorbed 0.2-10 keV X-ray luminosity. Overplotted are PARSEC isochrones for stellar populations of 40 Myr (blue) and 4 Gyr (red). Sources above the empirical cut in the X-ray main sequence diagram are labeled with black source IDs, while two γ Cas candidates are marked in red. Two extremely “red” outliers are marked as SySt candidates. Low-confidence matches are shown as open black circles.