Sky distribution of the H I detections identified with SoFiA. The inner dashed grey circle represents the R₂₀₀ of A2626, and the outer light blue dashed circle represents the primary beam FWHM at the frequency of the cluster. The black contours represent the x-ray emission from A2626 taken from ROSAT images. The data points representing the H I detections are coloured by the spectral over-density of which they are a member. The blue indicates likely Perseus-Pegasus filament galaxies (0.035 <  z <  0.0425), green are A2626 galaxies (0.0475 <  z <  0.0615), orange are galaxies in The Swarm (0.0615 <  z <  0.0675), and magenta galaxies represent galaxies part of A2637 (0.0675 <  z <  0.0745); see Sect. 7 for more details. The open squares represent the galaxies also detected by ALFALFA that are used in the H I flux density comparison in Sect. 5.1.