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Early Data Release (EDR)

Overview

The DESI Early Data Release includes spectra for 1.8 million unique targets from Survey Validation observations taken from December 2020 through June 2021, as well as a few commissioning and special tiles observed during the same time period. These data include “Target Selection Validation” (sv1) observations with looser target selection cuts and deeper S/N spectra, and “One-Percent Survey” (sv3) observations with highly complete coverage over 20 different fields overlapping other major surveys.

The EDR data are released under the Creative Commons Attribution 4.0 International License (CC BY 4.0). Use of DESI data requires including the citation and acknowledgment text given on the Data License and Acknowledgments page.

Data URL: https://data.desi.lbl.gov/public/edr

For a full description of the Survey Validation observations and EDR data, see DESI Collaboration et al. (2024) and DESI Collaboration et al. (2024). For an overview of how DESI data are organized see Data Organization, and see Data Access for how to access the data.

Coverage area

The figure below shows tile centers of the DESI observations included in EDR. The colored symbols the 20 rosette locations that compose the ~175 square degrees of the DESI One-Percent Survey (sv3). Each location was observed at least 12 times with overlapping tile centers to ensure a fiber assignment completeness of at least 95% for ELG and MWS targets, and over 99% for BGS, LRGs, and quasars targets within the central 6.5 square degrees of each rosette. In addition to these highly complete areas covering datasets from other surveys, EDR includes ~1200 additional square degrees covered by tiles with lower completeness but deeper S/N, centered at black dots in the figure.

One-Percent Survey coverage

Summary statistics

Summary of EDR
Number of HEALPixel coadded spectra(1)

2,044,588
Number of useful(2) spectra

1,769,157
Number of useful spectra of unique targets 1,712,004

Galaxies (SPECTYPE==GALAXY)

 1,125,635

Quasars (SPECTYPE==QSO)

 90,241

Stars (SPECTYPE==STAR)

 496,128
Spectral coverage(3) 360–982.4 nm
Spectral resolution R 2000 (at 360 nm)–5500 (at 980 nm)
Wavelength system vacuum
Photometric bands (Legacy Surveys DR9) g, r, z, W1, W2, W3, W4
Approximate area ~1390 square degrees

Footnotes: (1) Number of spectra for fibers placed on targets (OBJTYPE==TGT), which excludes sky fibers and known faulty fibers. (2) Useful spectra defined as having ZWARN==0, which means no errors due to instrument or data and no flags from spectral fitting issues. (3) Spectra are split on three spectrograph arms: blue (B), red (R), infrared (Z).

Table 6 from DESI Collaboration et al. (2024), reproduced below, contains the number of “good” spectra obtained for each DESI target class in each phase of Survey Validation, along with details for dedicated pointings (special) and commissioning (cmx). “Good” refers to science targets that have no Redrock redshift warning bits set (e.g. ZWARN==0) and whose best-fitting templates are consistent with the tracer (e.g. SPECTYPE==GALAXY for LRG and ELG targets, and SPECTYPE==QSO for QSO targets).

Survey Validation Phase NBGS NELG NLRG NQSO NSTAR
Commissioning (cmx) 247 761 1,037 275 468
Target Selection Validation (sv1) 134,419 111,692 66,161 29,839 163,254
Operations Testing (sv2) 46,628 12,308 22,151 11,032 10,506
One-Percent Survey (sv3) 253,915 312,790 137,317 34,173 295,232
Special 925 3,866 3,588 3,045 867
Total 428,758 437,664 227,318 76,079 466,447

Redshift distributions

The following figure (Figure 2 of DESI Collaboration et al. (2024)) shows the number of good, unique target redshifts as a function of redshift for each tracer type: ELG (green), LRG (red), BGS (purple), and QSO (blue). Stars are shown in the top panel. The gray histograms (e.g. STAR*, GALAXY*, QSO*) include all objects of a given SPECTYPE classification, regardless of their target type. These differ slightly from the colored histograms because of secondary targets and other target types that were classified to a different category (e.g. a QSO target that was classified as a star).

EDR n(z)

Value-added Catalogs

The DESI science collaboration has generated a set of value-added catalogs (VACs) to accompany the Early Data Release. These catalogs provide curated subsets of data with additional analysis beyond the core spectroscopic data processing pipeline outputs.

Available now

Coming soon

The following VACs are currently in development:

  • Active Galactic Nuclei (AGN) Summary Catalog
  • QuasarNET Catalog

Known Issues

Known issues with the Early Data Release are documented here.

Software Package Versions

The versions of DESI software packages used for the Early Data Release are available here.