VII/300 DESI Legacy Imaging Surveys DR10 phot. redshifts of galaxies (Li+, 2024)
A Photometric Redshift Catalogue of Galaxies from the DESI Legacy Imaging
Surveys DR10.
Li C., Zhang Y., Cui C., Wei S., Zhang J., Zhao Y., Wu X.-B., Tao Y.,
Li S., Wang Y., Kang Z.
<Astron. J., 168, 233 (2024)>
=2024AJ....168..233L 2024AJ....168..233L
ADC_Keywords: Surveys ; Redshifts ; Optical
Keywords: Galaxy distances ; Algorithms ; Astrostatistics ; Galaxy photometry ;
Sky surveys ; Catalogs
Abstract:
The large-scale measurement of galaxy redshifts holds significant
importance for cosmological research, as well as for understanding the
formation and evolution of galaxies. This study utilizes a known
sample obtained by cross-correlating the Dark Energy Spectroscopic
Instrument (DESI) Legacy Imaging Surveys DR10 galaxy catalog with
various galaxy catalogs from different spectroscopic surveys. The
methods Easy and Accurate Photometric Redshifts from Yale (EAZY) and
CatBoost are employed to estimate redshifts. In the case of EAZY, the
known sample is used solely for testing, while CatBoost utilizes it
for both training and testing purposes. The known sample is
categorized into different subsamples based on various classification
methods. Several CatBoost regression models are trained and optimized
using these subsamples. By comparing the performance of different
methods and models, it is observed that the two-step and two-part
models outperform the one-step model, with further enhancements
achieved through the combination of the two-step and two-part models.
Based on the findings from all experiments, we propose a photometric
redshift estimation workflow designed to facilitate the photometric
redshift measurement of all galaxies within the DESI Legacy Imaging
Surveys DR10. Consequently, a photometric redshift catalog has been
released, comprising a total of 1,533,107,988 galaxies. Among these,
312,960,837 galaxies have reliable redshift estimates, determined
using the CatBoost algorithm, with magnitude limits set at g>24.0,
r>23.4, and z>22.5. For galaxies with g, r, and z magnitudes exceeding
these thresholds, the photometric redshifts estimated by EAZY can be
employed as a reference.
Description:
The spectroscopic redshifts are used as true labeled values for
training an estimator of photometric redshifts by the machine-learning
method applied to the DESI Legacy Imaging Surveys DR10 data. The
methods Easy and Accurate Photometric Redshifts from Yale (EAZY) and
CatBoost are employed to estimate redshifts. In the case of EAZY, the
known sample is used solely for testing, while CatBoost utilizes it
for both training and testing purposes.
We compile a known spectroscopic redshift sample from
different spectroscopic surveys, including the Two Degree Field Galaxy
Redshift Survey (2dFGRS; Colless+2001, VII/250), the Six Degree Field
Galaxy Survey (6dFGS; Jones+2009, VII/259), the Complete Calibration
of the Color-Redshift Relation survey (C3R2; Masters+2017,J/ApJ/841/111),
the AGN and Galaxy Evolution Survey (AGES; Kochanek+2012, J/ApJS/200/8),
the VIMOS VLT Deep Survey (VVDS; Le Fevre+2013, J/A+A/559/A14),
VANDELS (Garilli+2021, J/A+A/647/A150), the UKIDSS Ultra-Deep Survey
(UDSz; Bradshaw+2013; McLure+2013), zCOSMOS (Lilly+2009, J/ApJS/184/218),
the DEEP2 Galaxy Redshift Survey (DEEP2; Newman+2013), the Prism
Multi-object Survey (PRIMUS; Coil+2011; Cool+2013), the Fiber Multi-Object
Spectrograph COSMOS survey (FCOSMOS; Kashino+2019), the VIMOS Public
Extragalactic Redshift Survey (VIPERS; Scodeggio+2018, J/A+A/609/A84),
the Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR8
(LAMOST DR11, Luo+2026, V/162), the WiggleZ DES
(WiggleZ; Drinkwater+2018, J/MNRAS/474/4151), the Galaxy And Mass
Assembly (GAMA; Liske+2015, J/MNRAS/452/2087) DR3, the Sloan Digital
Sky Survey (SDSS; York+2000) DR17 (Abdurro'uf+2022, III/286), and
OzDES (Lidman+2020, J/MNRAS/496/19). We perform a positional
cross-match within a 1" radius between the sample with known spectroscopic
redshifts and the DESI Legacy Imaging Surveys DR10 galaxy sample,
forming the cross-matched catalog used as the Known Samples for Training
and Test (KST).
The Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys
(Dey+2019AJ....157..168D) aims to provide galaxy and quasar targets
for follow-up observation by DESI. In 2022, DR10 was released, which
included all images from the Dark Energy Camera Legacy Survey
(DECaLS), the Beijing-Arizona Sky Survey (BASS; Zou+2017PASP..129f4101Z),
and the the Mayall z-band Legacy Survey (MzLS). Meanwhile, DR10 also
includes Dark Energy Camera (DECam) observations from a range of
non-DECaLS surveys, such as the Dark Energy Survey (DES), DELVE
Survey, and the DeROSITA Survey. The sky area in DR10 is up to
20,000deg2. The force photometries on W1 and W2 bands of the unWISE
(Schlafly+2019, II/363) coadded images are obtained. DR10 provides
i-band fluxes for the first time. We compute the AB magnitudes
corresponding to the model and aperture fluxes in g, r, i, z, W1, and
W2 bands. We delete all galaxies with maskbits!=0. After that, the
galaxy sample from DESI DR10 catalog is built.
EAZY (Brammer+2008ApJ...686.1503B) is a publicly available and excellent
photometric redshift code based on template-fitting algorithm.
CatBoost (Dorogush+2018arXiv181011363V) represents an optimized,
high-performance open-source gradient boosting algorithm (Friedman+2001).
Acknowledgements:
This research used data obtained with the Dark Energy Spectroscopic
Instrument (DESI). DESI construction and operations is managed by the
Lawrence Berkeley National Laboratory. This material is based upon
work supported by the U.S. Department of Energy, Office of Science,
Office of High-Energy Physics, under Contract No. DE-AC02-05CH11231,
and by the National Energy Research Scientific Computing Center, a DOE
Office of Science User Facility under the same contract. Additional
support for DESI was provided by the U.S. National Science Foundation
(NSF), Division of Astronomical Sciences under Contract No. AST-0950945
to the NSF's National Optical-Infrared Astronomy Research Laboratory;
the Science and Technology Facilities Council of the United Kingdom;
the Gordon and Betty Moore Foundation; the Heising-Simons Foundation;
the French Alternative Energies and Atomic Energy Commission (CEA);
the National Council of Humanities, Science and Technology of Mexico
(CONAHCYT); the Ministry of Science and Innovation of Spain (MICINN),
and by the DESI Member Institutions:
http://www.desi.lbl.gov/collaborating-institutions. The DESI
collaboration is honored to be permitted to conduct scientific
research on I'oligam Du'ag (Kitt Peak), a mountain with particular
significance to the Tohono O'odham Nation. Any opinions, findings, and
conclusions or recommendations expressed in this material are those of
the author(s) and do not necessarily reflect the views of the U.S.
National Science Foundation, the U.S. Department of Energy, or any of
the listed funding agencies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
desils10.sam 208 1000 Legacy Surveys DR10 photometric redshifts catalog
of galaxies
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See also:
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)
VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)
V/162 : LAMOST DR11 catalogs (Luo+, 2026)
VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022)
J/ApJS/184/218 : The zCOSMOS 10k-bright spectroscopic sample (Lilly+, 2009)
J/ApJS/200/8 : AGES: the AGN and Galaxy Evolution Survey (Kochanek+, 2012)
J/A+A/559/A14 : VIMOS VLT Deep Survey final data release (Le Fevre+, 2013)
J/MNRAS/452/2087 : Galaxy And Mass Assembly (GAMA): DR2 (Liske+, 2015)
J/ApJ/841/111 : C3R2 surv: high-confidence redshifts from DR1 (Masters+, 2017)
J/MNRAS/474/4151 : WiggleZ Dark Energy Survey final DR (Drinkwater+, 2018)
J/A+A/611/A97 : Phot. quasar candidates in Stripe 82 (Pasquet-Itam+, 2018)
J/A+A/609/A84 : VIPERS spectroscopic redshifts (PDR-2) (Scodeggio+, 2018)
J/MNRAS/496/19 : OzDES DR2 redshift catalogue (Lidman+, 2020)
J/A+A/647/A150 : VANDELS ESO public spectroscopic survey. DR4 (Garilli+, 2021)
J/ApJS/258/11 : The COSMOS2020 catalog (Weaver+, 2022)
Byte-by-byte Description of file: desils10.sam
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Bytes Format Units Label Explanations
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1- 16 F16.12 deg RA_J2000 Right ascension (J2000) (ra)
18- 33 F16.12 deg DE_J2000 Declination (J2000) (dec)
35- 39 I5 --- Release [10000] LS DR10 release number - denoting the
camera and filter set used (release)
41- 46 I6 --- BrickID [2/524413] LS DR10 brick number (brickid)
48- 52 I5 --- ObjID [0/62674] LS DR10 catalogue object number
within this brick (objid)
54- 63 F10.6 mag gmag ? g-band AB magnitude (MAG_G)
65- 73 F9.6 mag rmag ? r-band AB magnitude (MAG_R)
75- 84 F10.6 mag imag ? i-band AB magnitude (MAG_I)
86- 94 F9.6 mag zmag ? z-band AB magnitude (MAG_Z)
96- 104 F9.6 mag W1mag ? UnWISE W1-band AB magnitude (MAG_W1)
106- 114 F9.6 mag W2mag ? UnWISE W2-band AB magnitude (MAG_W2)
116- 128 E13.6 --- fqual ? Photometric redshift estimation quality
with EAZY (q_z)
130- 135 I6 --- maskbits LS photometric quality flag; maskbits=0
indicates uncontaminated photometry
137- 146 F10.6 --- z-EASY Photometric redshift estimated and calibrated
by EAZY (z_eazy)
148- 157 F10.6 --- Prob Probability density at the peak of p(z)
estimated by EAZY (peak_prob)
159 I1 --- labelp Predictions of the first-step classification
model in the two-step model of CatBoost
161- 168 F8.6 --- labelpb Prediction probabilities of the first-step
classifier in the CatBoost two-step model
170- 178 F9.6 --- z-CBbp Photometric redshift estimated by the
two-step model of CatBoost (redshift_bp)
180- 188 F9.6 --- z-CBp Photometric redshift estimated by the
one-step model of CatBoost (redshift_p)
190- 198 F9.6 --- z-CBm Photometric redshift estimated by the
two-part model of CatBoost (redshift_m)
200- 208 F9.6 --- z Optimal photometric redshift of the combined
one-step; two-step; and two-part models of
CatBoost (redshift)
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History:
From https://nadc.china-vo.org/res/r101486/
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(End) Prepared by [AAS], Robin Leichtnam [CDS] 15-Sep-2026