Distribution of the parameters (seeing, ellipticity and magnitude limit per stack image) assessing the high quality of the VVV images used for obtaining our new photometric dataset. We show the ZY JH filters (upper panels) and the K_s filter (lower panels). In the left and central panels, the green and blue filled histograms correspond to epoch 1, while the gray and red empty histograms correspond to epoch 2. In the right panels, the difference between the magnitude limits is in the sense of first epoch minus second epoch. In the upper right panel, we have omitted from the comparison the images from the disk in Z and Y due to the different exposure times between epochs (see Table 1). We note that the higher quality of the K_s images on average is due to having more images to select from.