Published online by Cambridge University Press: 12 April 2016
The passbands of the Johnson JHKL broadband photometric system used at a number of major observatories have been compared to the atmospheric window transmissions calculated by MODTRAN, and a family of solar-composition model stellar fluxes from Kurucz (1991 private communication) have been used as input to model the atmospheric extinction under different water vapor content, altitude, and airmass conditions. A figure of merit related to the slope of the extinction curve at zero airmass describes the sensitivity of the response function to atmospheric extinction. We have compared passbands used at several observatories, and have designed an improved set of passbands.