Zero-level shift correction for the Effelsberg data. (a) Effelsberg 4.8 GHz continuum image. (b) Urumqi 6 cm continuum emission overlaid with the Effelsberg 4.8 GHz continuum contours. Both data sets have been convolved to an angular resolution of 15′. The contours start at 50 mK, and each contour is twice the previous one. (c) Difference map derived by subtracting the Urumqi 6 cm continuum emission from the Effelsberg 4.8 GHz continuum map in Fig. 3b. (d) Extended emission component of Fig. 3c derived by the background filter method. (e) Compact emission component derived by the background filter method. (f) Restored Effelsberg 4.8 GHz continuum image.