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Published June 1, 2017 | Published + Submitted
Journal Article Open

The Complete Calibration of the Color-Redshift Relation (C3R2) Survey: Survey Overview and Data Release 1


A key goal of the Stage IV dark energy experiments Euclid, LSST, and WFIRST is to measure the growth of structure with cosmic time from weak lensing analysis over large regions of the sky. Weak lensing cosmology will be challenging: in addition to highly accurate galaxy shape measurements, statistically robust and accurate photometric redshift (photo-z) estimates for billions of faint galaxies will be needed in order to reconstruct the three-dimensional matter distribution. Here we present an overview of and initial results from the Complete Calibration of the Color–Redshift Relation (C3R2) survey, which is designed specifically to calibrate the empirical galaxy color–redshift relation to the Euclid depth. These redshifts will also be important for the calibrations of LSST and WFIRST. The C3R2 survey is obtaining multiplexed observations with Keck (DEIMOS, LRIS, and MOSFIRE), the Gran Telescopio Canarias (GTC; OSIRIS), and the Very Large Telescope (VLT; FORS2 and KMOS) of a targeted sample of galaxies that are most important for the redshift calibration. We focus spectroscopic efforts on undersampled regions of galaxy color space identified in previous work in order to minimize the number of spectroscopic redshifts needed to map the color–redshift relation to the required accuracy. We present the C3R2 survey strategy and initial results, including the 1283 high-confidence redshifts obtained in the 2016A semester and released as Data Release 1.

Additional Information

© 2017 The American Astronomical Society. Received 2017 February 27; revised 2017 April 19; accepted 2017 April 19; published 2017 May 31. The authors thank the referee, Marcin Sawicki, for a helpful report that improved this paper. D.M. would like to thank Giuseppe Longo, Audrey Galametz, Sotiria Fotopoulou, and George Helou for helpful conversations. D.M., P.C., D.S., and J.R. acknowledge support by NASA ROSES grant 12-EUCLID12-0004. J.R. and D.S. are supported by JPL, run by Caltech for NASA. F.C. acknowledges support by MINECO grant ESP2015-88861. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Attached Files

Published - Masters_2017_ApJ_841_111.pdf

Submitted - 1704.06665.pdf


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