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We have followed the recommendations of the IAU Commission 25 Working Group on Infrared Extinction and Standardization and designed a new set of passbands for the near and intermediate IR which are minimally affected by water vapour, and should provide more reliable transformations compared with both past and present versions. Atmospheric window transmissions have been calculated using MODTRAN, and Kurucz's (1991) stellar atmosphere models have been used as sources, to model the atmospheric extinction under different water-vapor, height, and airmass conditions. We have devised and computed a figure of merit related to the curvature of the extinction function to describe the sensitivity of each response function to variations in water-vapor extinction. On the basis of a large number of numerical experiments and simulations and the figure of merit, we recommend an improved set of passbands, optimized for reproducibility and transformability of photometric results, minimizing the Forbes effect and thermal emission, but broadened as much as possible to increase throughput. This work has been supported by NSERC and University Research Grants to EFM.
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