Ultradeep KS imaging in the goods-N

Abstract

We present an ultradeep KS -band image that covers 0.5 × 0.5deg2 centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5σ depth of in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6 μm image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution KS image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the χ2 approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions of galaxies at various redshifts. We make available to the community our WIRCam KS -band image and catalog (94,951 objects in 0.25deg2), the Interactive Data Language pipeline used for reducing the WIRCam images, and our IRAC 3.6-8.0 μm catalog (16,950 objects in 0.06deg2 at 3.6 μm). With this improved KS and IRAC catalog and a large spectroscopic sample from our previous work, we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using KS and IRAC colors to select active galactic nuclei and galaxies at various redshifts. We also study a color selection of z = 0.65-1.2 galaxies using the KS , 3.6 μm, and 4.5 μm bands. © 2010 The American Astronomical Society.