Example of global skydip fit for a KID. Each square point represents one step in a skydip (made of eleven elevation steps). A series of 12 skydip scans are jointly used, spanning zenith opacities from 0.15 to 0.50 in the 1 mm band. The horizontal axis gives the sky effective temperature T_sky = T_atm[1 − e^−τ_ν x] in Kelvins, where τ_ν is the skydip zenith opacity found in the fit. The vertical axis shows the relative resonance frequency of the KID with respect to 1.9 GHz, given in MHz. The blue line is the linear model using the best-fit and coefficients (see Eq. (12)).