Skip to main content

Research Repository

Advanced Search

DESI complete calibration of the colour–redshift relation (DC3R2): results from early DESI data

McCullough, J; Gruen, D; Amon, A; Roodman, A; Masters, D; Raichoor, A; Schlegel, D; Canning, R; Castander, F J; DeRose, J; Miquel, R; Myles, J; Newman, J A; Slosar, A; Speagle, J; Wilson, M J; Aguilar, J; Ahlen, S; Bailey, S; Brooks, D; Claybaugh, T; Cole, S; Dawson, K; de la Macorra, A; Doel, P; Forero-Romero, J E; Gontcho A Gontcho, S; Guy, J; Kehoe, R; Kremin, A; Landriau, M; Le Guillou, L; Levi, M; Manera, M; Martini, P; Meisner, A; Moustakas, J; Nie, J; Percival, W J; Poppett, C; Prada, F; Rezaie, M; Rossi, G; Sanchez, E; Seo, H; Tarlé, G; Weaver, B A; Zhou, Z; Zou, H; DESI Collaboration

DESI complete calibration of the colour–redshift relation (DC3R2): results from early DESI data Thumbnail


J McCullough

D Gruen

A Amon

A Roodman

D Masters

A Raichoor

D Schlegel

R Canning

F J Castander

J DeRose

R Miquel

J Myles

J A Newman

A Slosar

J Speagle

M J Wilson

J Aguilar

S Ahlen

S Bailey

D Brooks

T Claybaugh

K Dawson

A de la Macorra

P Doel

J E Forero-Romero

S Gontcho A Gontcho

J Guy

R Kehoe

A Kremin

M Landriau

L Le Guillou

M Levi

M Manera

P Martini

A Meisner

J Moustakas

J Nie

W J Percival

C Poppett

F Prada

M Rezaie

G Rossi

E Sanchez

H Seo

G Tarlé

B A Weaver

Z Zhou

H Zou

DESI Collaboration


We present initial results from the Dark Energy Spectroscopic Instrument (DESI) complete calibration of the colour–redshift relation (DC3R2) secondary target survey. Our analysis uses 230 k galaxies that overlap with KiDS-VIKING ugriZYJHKs photometry to calibrate the colour–redshift relation and to inform photometric redshift (photo-z) inference methods of future weak lensing surveys. Together with emission line galaxies (ELGs), luminous red galaxies (LRGs), and the Bright Galaxy Survey (BGS) that provide samples of complementary colour, the DC3R2 targets help DESI to span 56 per cent of the colour space visible to Euclid and LSST with high confidence spectroscopic redshifts. The effects of spectroscopic completeness and quality are explored, as well as systematic uncertainties introduced with the use of common Self-Organizing Maps trained on different photometry than the analysis sample. We further examine the dependence of redshift on magnitude at fixed colour, important for the use of bright galaxy spectra to calibrate redshifts in a fainter photometric galaxy sample. We find that noise in the KiDS-VIKING photometry introduces a dominant, apparent magnitude dependence of redshift at fixed colour, which indicates a need for carefully chosen deep drilling fields, and survey simulation to model this effect for future weak lensing surveys.


McCullough, J., Gruen, D., Amon, A., Roodman, A., Masters, D., Raichoor, A., …DESI Collaboration. (2024). DESI complete calibration of the colour–redshift relation (DC3R2): results from early DESI data. Monthly Notices of the Royal Astronomical Society, 531(2), 2582-2602.

Journal Article Type Article
Acceptance Date May 9, 2024
Online Publication Date Jun 3, 2024
Publication Date 2024-06
Deposit Date Jul 4, 2024
Publicly Available Date Jul 4, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 531
Issue 2
Pages 2582-2602
Public URL


You might also like

Downloadable Citations