Structural Parameters of Galaxies in CANDELS

We present global structural parameter measurements of 109,533 unique, H _F160W-selected objects from the CANDELS multi-cycle treasury program. Sérsic model fits for these objects are produced with GALFIT in all available near-infrared filters (H _F160W, J _F125W and, for a subset, Y _F105W). The parameters of the best-fitting Sérsic models (total magnitude, half-light radius, Sérsic index, axis ratio, and position angle) are made public, along with newly constructed point-spread functions for each field and filter. Random uncertainties in the measured parameters are estimated for each individual object based on a comparison between multiple, independent measurements of the same set of objects. To quantify systematic uncertainties, we create a mosaic with simulated galaxy images with a realistic distribution of input parameters and then process and analyze the mosaic in an identical manner as the real data. We find that accurate and precise measurements—to 10% or better—of all structural parameters can typically be obtained for galaxies with H _F160W < 23, with comparable fidelity for basic size and shape measurements for galaxies to H _F160W ~ 24.5.