Two measures of the red-leak for the 16 NB118 filters. The y-axis shows the level in screen flats obtained with the lights in the dome off (i.e. with the light source being the thermal emission from the dome flat screen, the dome, etc.) divided by the level in regular screen flats (i.e. with the dome flat screen illuminated by a lamp). The levels have been dark subtracted. The x-axis shows correlation coefficients between the NB118 sky brightness in the given detector (i.e. filter) and the ambient temperature using all the VISTA data contained in the CASU QC tables. The correlation coefficients have been multiplied by minus one, since they would otherwise be negative due to the sky brightness being in mag/arcsec². Panel a) shows the Spearman rank order correlation coefficient r_S while panel b) shows the linear Pearson correlation coefficient r_P. The labels indicate the detector number.