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DESI DR1 Stellar Catalogue of Radial Velocities, Abundances, and Atmospheric Parameters

Milky Way Survey

The density of objects in the stellar catalogue for different programs in the main DESI survey.

Overview

This VAC release includes the results of processing stellar spectra in DESI DR1 by the RVSpecFit (RVS) and FERRE (SP) spectroscopic pipelines. This release is described in detail in the paper by Koposov et al. (2025).

This VAC includes measurements of likely stars observed in different programs and surveys by DESI. E.g. among others it includes stars observed in the bright program (Milky Way Survey; Cooper et al. (2023) ) and in the backup program ( Dey et al. (2025) )

The objects that were analyzed for this release were selected if they satisfy any of the following criteria:

  • Object was targeted by the Milky Way Survey (MWS)
  • Object was targeted as a spectrophotometric standard
  • Object was classified as a star based on a coadded spectrum by Redrock
  • Object has a low Redrock redshift in the coadded spectrum (absolute value of velocity less than 1500 km/s)
  • Object was targeted as a secondary target

The pipelines are described in the MWS overview paper by Cooper et al. (2023), the Early Data Release MWS value-added catalogue paper Koposov et al. (2024) and DR1 stellar catalogue paper Koposov et al. (2025).

The RVS pipeline fits DESI spectra using interpolated PHOENIX stellar templates to obtain radial velocities and stellar parameters. The SP pipeline models the continuum-normalized spectra to obtain stellar parameters and stellar abundances using PHOENIX and Kurutz model atmospheres.

The DR1 release is based on significantly improved stellar parameter estimation by the RVS pipeline, thanks to the use of neural networks for interpolation of stellar templates.

This release includes not only measurements from stacked spectra, but also measurement radial velocities and stellar parameters (from RVS) for single-epoch spectra.

Key statistics for this release:

  • The total number of fitted coadded spectra included in the release: 6,372,607
  • The number of unique DESI sources, spectroscopically classified as stars: 4,586,247
  • The number of unique Gaia sources in the catalogue: 4,920,596
  • The number of single-epoch spectra with stellar parameters and radial velocities: 10,012,925
  • The number of Gaia sources with more than one radial velocity/stellar parameter measurement: 1,718,305
  • The largest number of sources in the catalogue has been observed in the bright program of the main survey (3,070,120), followed by the dark program of the main survey (1,357,709), and the backup program of the main survey (1,218,152)

This release includes:

  • Stellar parameters and radial velocities from RVSpecFit fits to coadded spectra of likely stars in the DESI Data Release 1, grouped by Healpix pixels on the sky (RVTAB files in rv_output/240520)
  • Stellar parameters and radial velocities from RVS fits to single-epoch spectra of likely stars in the DESI Data Release 1, grouped by Healpix pixels on the sky (RVTAB files in rv_output/240521)
  • Stellar parameters from the SP pipeline fits to coadded spectra (SPTAB files in sp_output/230211)
  • Best-fit spectral models from RVS and SP pipelines (RVMOD files in rv_output/ and SPMOD files in sp_output/)
  • Combined catalogs from RVS and SP grouped by different survey/program (rvpix-[SURVEY]-[PROGRAM].fits and sppix-[SURVEY]-[PROGRAM].fits files)
  • Combined catalogue of measurements for all stars across survey/programs and with best/primary observation (based on spectrum quality) indicated (mwsall-pix-iron.fits)

The combined catalogs typically store measurements from RVSpecFit and/or FERRE, but also include FITS extensions from the DESI pipeline, such as FIBERMAP and SCORES, that contain information about targeting and spectral quality. The combined catalogs also have a separate extension with the crossmatch with Gaia DR3.

Known issues

The list of known issues is described in the paper Koposov et al. (2025). The most important ones include the systematic errors for the backup program radial velocities (the correction is provided in the paper), and the surface gravity and effective temperature dependent biases in the [Fe/H] (the correction is provided in the paper and in this repository.

Data Access

Data URL: https://data.desi.lbl.gov/public/dr1/vac/dr1/mws/iron/v1.0/

NERSC access: 

/global/cfs/cdirs/desi/public/dr1/vac/dr1/mws/iron/v1.0/

Tutorials

A brief tutorial illustrating the catalogue use is provided here:

https://github.com/desimilkyway/dr1_tutorials/

Relevant papers

Documentation

Data model

The full directory structure and data model for all products in this VAC are described here.

File contents summary (examples)

  • mwsall-pix-iron.fits
    Combined catalogue from all surveys and RVSpecFit/FERRE pipelines
  • rv_output/240520/rvpix-sv2-dark.fits
    Combined RVSpecFit measurement table for survey sv2, program dark
  • rv_output/240520/healpix/cmx/other/21/2152/rvtab_coadd-cmx-other-2152.fits
    RVSpecFit measurements for stars in Healpix pixel 2152 observed under survey cmx and program other
  • rv_output/240520/healpix/cmx/other/21/2152/rvmod_coadd-cmx-other-2152.fits
    RVSpecFit model spectra for stars in Healpix pixel 2152 observed under survey cmx, program other
  • rv_output/240521/rvpix_exp-main-bright.fits
    Combined catalogue of RVSpecFit fits to individual spectra in the main survey, bright program
  • rv_output/240521/healpix/cmx/other/21/2152/rvtab_spectra-cmx-other-2152.fits
    RVSpecFit measurements from individual epochs of observations for stars in Healpix pixel 2152 observed under cmx survey and program other
  • rv_output/240521/healpix/cmx/other/21/2152/rvmod_spectra-cmx-other-2152.fits
    RVSpecFit measurements from individual epochs of observations for stars in Healpix pixel 2152 observed under cmx survey and program other
  • sp_output/230211/sppix-sv2-backup.fits
    Combined FERRE measurement table for sv2 survey, program backup
  • sp_output/230211/healpix/sv1/backup/76/7664/sptab_coadd-sv1-backup-7664.fits
    FERRE measurements for stars in Healpix pixel 7664 observed in sv1 survey, backup program
  • sp_output/230211/healpix/sv1/backup/76/7665/spmod_coadd-sv1-backup-7665.fits
    FERRE best-fit spectral models for stars in Healpix pixel 7665 in sv1 survey, backup program

Software package versions

  • RVSpecFit: 0.4.0.240116+dev4611b3 (used for the fits of coadded spectra) and 0.4.0.240116+devc99319 (used for the fits of single-epoch spectra)
  • PIFERRE: 0.4
  • FERRE: 5.1.1

Contact

Contact Sergey Koposov or Carlos Allende with any questions.