The spitzer-hetdex exploratory large-area survey

Abstract

We present post-cryogenic Spitzer imaging at 3.6 and 4.5 mu m with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers approximate to 24 deg(2) of the Sloan Digital Sky Survey "Stripe 82" region, and falls within the footprints of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R similar to 800 spectroscopy will produce similar to 200,000 redshifts from the Ly alpha emission for galaxies in the range 1.9 < z < 3.5, and an additional similar to 200,000 redshifts from the [O II] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of similar to 0.5. Gpc(3) at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 mu m images. The catalogs reach limiting sensitivities of 1.1. mu Jy at both 3.6 and 4.5 mu m (1 sigma, for R = 2 '' circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.