Layout of the eFEDS field for the SPIDERS targeting and observations. The eROSITA X-ray coverage of the eFEDS field is shown in green, with the region with > 500 s of effective exposure depth shown with connected green points. SDSS-V plates are indicated as large black circles. The eFEDS Main X-ray sample is marked with small orange dots. The main sample sources having reliable spectroscopic redshifts (NORMQ = 3, see Table 2) are shown in dark blue, with red points indicating cases with unreliable redshift estimates (NORMQ < 3). The black diamonds indicate the objects that were detected in the X-ray as point-like sources, but which have counterparts suggesting that the source is likely associated with a galaxy cluster (CLUSTER_CLASS ≥ 4 from Salvato et al. 2022). The horizontal dashed line indicates the cut in δ(J2000) = − 2°, below which almost no SDSS plate observations are available, and which increases the spectroscopic completeness.