The Near-Infrared Camera and Multi-Object Spectrometer Ultra Deep Field: Observations, data reduction, and galaxy photometry

This paper describes the observations and data reduction techniques for the version 2.0 images and catalog of the Near-Infrared Camera and Multi-Object Spectrometer Ultra Deep Field (NICMOS UDF) Treasury program. All sources discussed in this paper are based on detections in the combined NICMOS F110W and F160W bands only. The NICMOS images are drizzled to 0.'' 09 pixel(-1) and aligned to the Advanced Camera for Surveys UDF F850LP image, which was rebinned to the same pixel scale. These form the NICMOS version 2.0 UDF images. The catalog sources are chosen with a conservative detection limit to avoid the inclusion of numerous spurious sources. The catalog contains 1293 objects in the 144 '' x 144 '' NICMOS subfield of the UDF. The 5 sigma signal-to-noise ratio level is an average 0.'' 6 diameter aperture AB magnitude of 27.7 at 1.1 and 1.6 mu m. The catalog sources, listed in order of right ascension, satisfy a minimum signal-to-noise ratio criterion of 1.4 sigma in at least seven contiguous pixels of the combined F110W and F160W image.