Correlator offset seen in sky images. The correlator offset problem discussed in the text is also manifested by blob-like features when imaging the tileset FoV. Here the left and right upper panels show FoV images of Cygnus A, and towards an empty sky position, based on uncorrected cross correlations. The bottom panels show the same data but with images created from cross correlations corrected by subtracting a reference matrix of complex constants (the same reference was used for both images). In the left bottom panel, Cygnus A is now clearly seen and at its expected position (offset from centre due to the scheme outlined in Fig. 6).