Deep H-Band Galaxy Counts and Half-Light Radii from Hubble Space Telescope/NICMOS Parallel Observations

Abstract

We present deep galaxy counts and half-light radii from F160W (λ_c=1.6 μm) images obtained with the Near-Infrared Camera and Multiobject Spectrograph on the Hubble Space Telescope. Nearly 9 arcmin² have been imaged with camera 3, with 3 σ depths ranging from H=24.3 to 25.5 in a 0.6" diameter aperture. The slope of the counts fainter than H=20 is 0.31, and the integrated surface density to H<=24.75 is 4×10⁵ galaxies deg^-2. The half-light radii of the galaxies decline steeply with apparent magnitude. At H=24, we are limited by both the delivered FWHM and the detection threshold of the images.