HST-NICMOS Color Transformations and Photometric Calibrations
Andrew W. Stephens, Jay A. Frogel, Sergio Ortolani, Roger Davies, Pascale Jablonka, Alvio Renzini, R. Michael Rich
Abstract
This paper presents color transformations for HST NICMOS camera 2 observations to the ground-based CIT/CTIO photometric system, using observations of nineteen moderately bright, red stars in Baade's window in the color range 0.7 < (J-K) < 1.6. We estimate an extension of the transformation to 0.4 < (J-K) < 3.0 with five standards observed by STScI. Convolving near-IR spectra taken above the atmosphere with different filter transmission profiles, we simulate both NICMOS and ground-based photometry, obtaining results which are consistent with our transformation and its extension.