HST NICMOS Observations of FSC10214+4724

High-resolution, 1.10, 2.05, 2.12, and 2.15 micron imaging of the gravitationally lensed system FSC10214+4724 are presented. These data extend HST observations of the lens system to redder wavelengths, thus providing the highest resolution images to date of the rest-frame optical and narrow-line (i.e., H-alpha+[N II]) regions of the background quasar. The length of the arc in the wide-band continuum images increases with increasing wavelength, and the H-alpha+[N II] emission has a length in between that of the 1.10 and 2.05 microns. The structure of the arc changes from having an eastern and western peak at 1.10 microns to a single peak in the center at 2.05 microns. The changing structure and length of the arc can be understood in terms of a model where the background quasar consists of a region of scattered AGN light that dominates at 1.10 microns (rest-frame 3300 angstroms), surrounded by a more extended narrow-line region. An even more extended red stellar population would thus contribute light at 2.05 microns...