2003AJ....126.1090C

Element by element, we have combined the optical components in the three cameras of the Two Micron All Sky Survey (2MASS), and incorporated detector quantum efficiency curves and site-specific atmospheric transmissions, to create three relative spectral response curves (RSRs). We provide the absolute 2MASS attributes associated with ``zero magnitude'' in the JHK<sub>s</sub> bands so that these RSRs may be used for synthetic photometry. The RSRs tie 2MASS to the ``Cohen-Walker-Witteborn'' framework of absolute photometry and stellar spectra for the purpose of using 2MASS data to support the development of absolute calibrators for the Infrared Array Camera and pairwise cross-calibrators between all three SIRTF instruments. We examine the robustness of these RSRs to changes in water vapor within a night. We compare the observed 2MASS magnitudes of 33 stars (converted from the precision optical calibrators of Landolt and Carter-Meadows into absolute infrared calibrators from 1.2 to 35 µm) with our predictions, thereby deriving 2MASS ``zero-point offsets'' from the ensemble. These offsets are the final ingredients essential to merge 2MASS JHK_s data with our other absolutely calibrated bands and stellar spectra, and to support the creation of faint calibration stars for SIRTF.