Jeyhan S. Kartaltepe, Rochester Institute of TechnologyFollow
Mark Mozena, University of California, Santa Cruz
Dale Kocevski, University of Kentucky
Daniel H. McIntosh, University of Missouri-Kansas City
Jennifer Lotz, Space Telescope Science Institute
Eric F. Bell, University of Michigan-Ann Arbor
Sandy Faber, University of California, Santa Cruz
Harry Ferguson, Space Telescope Science Institute
David Koo, University of California, Santa Cruz
Robert Bassett, Swinburne University of Technology - Australia
Maksym Bernyk, Swinburne University of Technology - Australia
Kirsten Blancato, Wellesley College
Darren Croton, Swinburne University of Technology - Australia
Tomas Dahlen, Space Telescope Science Institute
Frederic Bournaud, Université Paris Diderot
Paolo Cassata, Aix Marseille Université
Marco Castellano, IINAFOsservatorio Astronomico di Roma
Edmond Cheung, University of California, Santa Cruz
Christopher J. Conselice, University of Nottingham
Duilia F. De Mello, Catholic University of America
Laura DeGroot, University of California, Riverside
Jennifer Donley, Los Alamos National Laboratory
Javiera Guedes, ETH Zurich
Norman Grogin, Space Telescope Science Institute
Nimish Hathi, University of California, Riverside
Matt Hilton, University of KwaZulu-Natal
Brett Hollon, University of Missouri-Kansas City
Anton Koekemoer, Space Telescope Science Institute
Nick Liu, Space Telescope Science Institute
Ray A. Lucas, Space Telescope Science Institute
Marie Martig, Swinburne University of Technology - Australia
Elizabeth McGrath, Colby College
Conor McPartland, University of Hawaii, Honolulu
Bahram Mobasher, University of California, Riverside
Alice Morlock, University of Nottingham
Erin O'Leary, Macalester College
Mike Peth, Johns Hopkins University
Janine Pforr, National Optical Astronomy Observatory
Annalisa Pillepich, Harvard-Smithsonian Center for Astrophysics
David Rosario, Max-Planck Institut für Astronomie
Emmaris Soto, Catholic University of America
Amber Straughn, NASA Goddard Space Flight Center
Olivia Telford, University of Washington, Seattle
Ben Sunnquist, University of Missouri-Kansas City
Jonathan Trump, Penn State
Benjamin Weiner, University of Arizona, Tucson
Stijn Wuyts, Max-Planck-Institut für Extraterrestrische Physik


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 over 65 individual classifiers. Once completed, we expect to have detailed morphological classifications for over 50,000 galaxies spanning 0 < z < 4 over all the fields, with classifications from 3 to 5 independent classifiers for each galaxy. 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, which has been classified at various depths. The wide area coverage spanning the full field (wide+deep+ERS) 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 Perl/Tk GUI that we developed to classify galaxies. We present our initial results here, including an analysis of our internal consistency and comparisons among multiple classifiers as well as a comparison to the Sérsic index. We find that the level of agreement among classifiers is quite good (>70% across the full magnitude range) and depends on both the galaxy magnitude and the galaxy type, with disks showing the highest level of agreement (>50%) and irregulars the lowest (<10%). A comparison of our classifications with the Sérsic 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.

Publication Date



Originally published in "The Astrophysical Journal Supplement Series" (2015); DOI: 10.1088/0067-0049/221/1/11

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus