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Galaxy Zoo: Morphological classifications for 120 000 galaxies in HST legacy imaging

Willett, Kyle W.; Galloway, Melanie A.; Bamford, Steven P.; Lintott, Chris J.; Masters, Karen L.; Scarlata, Claudia; Simmons, B. D.; Beck, Melanie; Cardamone, Carolin N.; Cheung, Edmond; Edmondson, Edward M.; Fortson, Lucy F.; Griffith, Roger L.; Häußler, Boris; Han, Anna; Hart, Ross; Melvin, Thomas; Parrish, Michael; Schawinski, Kevin; Smethurst, Rebecca J.; Smith, Arfon M.


Kyle W. Willett

Melanie A. Galloway

Chris J. Lintott

Karen L. Masters

Claudia Scarlata

B. D. Simmons

Melanie Beck

Carolin N. Cardamone

Edmond Cheung

Edward M. Edmondson

Lucy F. Fortson

Roger L. Griffith

Boris Häußler

Anna Han

Ross Hart

Thomas Melvin

Michael Parrish

Kevin Schawinski

Rebecca J. Smethurst

Arfon M. Smith


© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. We present the data release paper for the Galaxy Zoo: Hubble (GZH) project. This is the third phase in a large effort to measure reliable, detailed morphologies of galaxies by using crowdsourced visual classifications of colour-composite images. Images in GZH were selected from various publicly released Hubble Space Telescope legacy programmes conducted with the Advanced Camera for Surveys, with filters that probe the rest-frame optical emission from galaxies out to z ~ 1. The bulk of the sample is selected to have mI814W < 23.5, but goes as faint as mI814W < 26.8 for deep images combined over five epochs. The median redshift of the combined samples is 〈 z 〉 = 0.9 ± 0.6, with a tail extending out to z ≃ 4. The GZH morphological data include measurements of both bulge- and disc-dominated galaxies, details on spiral disc structure that relate to the Hubble type, bar identification, and numerous measurements of clump identification and geometry. This paper also describes a new method for calibrating morphologies for galaxies of different luminosities and at different redshifts by using artificially redshifted galaxy images as a baseline. The GZH catalogue contains both raw and calibrated morphological vote fractions for 119 849 galaxies, providing the largest data set to date suitable for large-scale studies of galaxy evolution out to z ~ 1.


Willett, K. W., Galloway, M. A., Bamford, S. P., Lintott, C. J., Masters, K. L., Scarlata, C., …Smith, A. M. (2017). Galaxy Zoo: Morphological classifications for 120 000 galaxies in HST legacy imaging. Monthly Notices of the Royal Astronomical Society, 464(4), 4176-4203.

Journal Article Type Article
Acceptance Date Oct 5, 2016
Online Publication Date Oct 8, 2016
Publication Date Feb 1, 2017
Deposit Date Jan 6, 2017
Publicly Available Date Jan 6, 2017
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 464
Issue 4
Pages 4176-4203
Keywords methods: data analysis ; catalogues ; galaxies: evolution ; galaxies: highredshift ; galaxies: structure
Public URL
Publisher URL


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