Comparison between the VVV-SkZ_pipeline’s JHK_s photometry and that from the 2MASS catalogue. Since the VVV-SkZ_pipeline’s astrometric solution is based on the 2MASS catalogue, we were able to match most of the stars within a 1′′-radius. Red, big circles are the stars within the magnitude intervals used for the flux calibration, i.e. 12.5 < J < 14.5 mag, 11.5 < H < 13 mag and 11 < K_s < 12.5 mag. A dashed line shows where the VVV-SkZ_pipeline’s photometry perfectly matches the 2MASS values, and the dotted lines show the standard deviation of the points.