Vignetting-corrected XMM-Newton MOS1/2 color image of the field around PSR J2021+4026 (red: 0.5–1 keV; green: 1–2 keV; blue: 2–10 keV). The binning factor of this image is 1''. Adaptive smoothing has been applied to achieve a minimum signal-to-noise ratio of 3. The white cross illustrates the nominal geometrical center of SNR G78.2+2.1 (Green 2009). Soft diffuse emission is found in the field. The overlaid solid line ellipse illustrates the extraction region for the diffuse spectra of the southeastern rim of G78.2+2.1. The dashed ellipse shows the background region used in the remnant analysis. Including PSR J2021+4026 (source 18), 42 X-ray point sources detected by this observation are highlighted with the labels consistent with Table 1. Top is north and left is east.