Using detailed, quantified visual Galaxy Zoo morphologies of approximately 50,000 galaxies imaged by the Cosmic And Near-infrared Deep Extragalactic Legacy Survey (CANDELS), we report first results on the settling of massive disc galaxies from 0.5 < z < 2. The fraction of disc galaxies dynamically cold enough to support strong disc instabilities is constant from 1 < z < 2, in contrast to the vanishing fraction expected from extrapolation of previous rest-frame optical results to z = 1 but marginally consistent with the predictions of some simulations.

The full Galaxy Zoo CANDELS morphologies will also be released to the public: 85% of galaxies in the sample have redshifts 0.5 < z < 3, and they range in observed H-band surface brightness between 17.5 < µ < 27 mag/arcsec^2. Galaxy Zoo collects multiple independent classifications (typically 40) of each galaxy in the sample. After applying an iterative consensus-based classifier weighting scheme and correcting for the effects of varying image depth and distance, we report measurements of morphology along a variety of physically useful axes, such as clumpiness, spiral arm count and strength, bulge strength, and the presence of a bar instability. We demonstrate the utility of these classifications to the community by showing how these morphologies may be used to identify a population of completely featureless yet rotation-dominated disc galaxies.