Diagnostic plots of cross-matches between Fermi-LAT (4FGL-DR4) and SRG/eROSITA sources (eRASS:4)

This repository provides diagnostic plots used for visual inspection accompanying the paper "Searching for X-ray counterparts of unassociated Fermi-LAT sources and rotation-powered pulsars with SRG/eROSITA" by Martin G. F. Mayer and Werner Becker, published in Astronomy & Astrophysics in 2024. The attached tarball contains ~ 500 PDF files, one per Fermi source with at least one possible X-ray counterpart. In each file, the top row of panels displays the eROSITA (eRASS:4) X-ray image of the Fermi-LAT uncertainty region in the energy bands 0.2-0.6, 0.6-2.3, and 2.3-5.0 keV, overlaid with the 1 sigma (blue dashed line) and 95% error ellipse of the 4FGL source (blue solid line), and the position of the detected X-ray sources (red). The pixel size is 12 arcsec. For each X-ray source, the bottom panels show the local distribution of optical sources from Gaia DR3 (left), mid-infrared sources from CatWISE2020 (center), as well as SIMBAD entries and radio sources (right) around the respective X-ray source position (error bars). In the left and center panels, the size of the markers is proportional to the source brightness, and their color reflects the photometric colors (with bluer markers indicating bluer colors). In the left panel, pentagonal (triangular) markers correspond to sources with statistically significant (insignificant) proper motion or parallax, circular markers indicate the lack of a complete astrometric solution for a source.