CANDELS Visual Classifications: Scheme, Data Release, and First Results
  We have undertaken an ambitious program to visually classify all galaxies in
the five CANDELS fields down to H<24.5 involving the dedicated efforts of 65
individual classifiers. Once completed, we expect to have detailed
morphological classifications for over 50,000 galaxies up to z<4 over all the
fields. Here, we present our detailed visual classification scheme, which was
designed to cover a wide range of CANDELS science goals. This scheme includes
the basic Hubble sequence types, but also includes a detailed look at mergers
and interactions, the clumpiness of galaxies, $k$-corrections, and a variety of
other structural properties. In this paper, we focus on the first field to be
completed -- GOODS-S. The wide area coverage spanning the full field includes
7634 galaxies that have been classified by at least three different people. In
the deep area of the field, 2534 galaxies have been classified by at least five
different people at three different depths. With this paper, we release to the
public all of the visual classifications in GOODS-S along with the GUI that we
developed to classify galaxies. We find that the level of agreement among
classifiers is good and depends on both the galaxy magnitude and the galaxy
type, with disks showing the highest level of agreement and irregulars the
lowest. A comparison of our classifications with the Sersic index and
rest-frame colors shows a clear separation between disk and spheroid
populations. Finally, we explore morphological k-corrections between the V-band
and H-band observations and find that a small fraction (84 galaxies in total)
are classified as being very different between these two bands. These galaxies
typically have very clumpy and extended morphology or are very faint in the
V-band.
