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Fuji VAC (EDR)

This page describes the Fuji value-added catalog which was publicly released in December 2023 and is based on the DESI Early Data Release (DESI/EDR).

Please refer to the :ref:`acknowledgments` section for the conditions for using this VAC.

Note

We only document the latest version of this VAC here; please see below for information regarding :ref:`previous versions<previous versions - fuji>`.

Data from the Fuji VAC can be accessed at any of the following links:

Data url https://data.desi.lbl.gov/public/edr/vac/edr/fastspecfit/fuji/v3.2
Web-app (for collaborators) https://fastspecfit.desi.lbl.gov
NERSC (for collaborators) /global/cfs/cdirs/desi/public/edr/vac/edr/fastspecfit/fuji/v3.2

For more information regarding the content and organization of the VAC, please click on the following links:

The following table summarizes the size and number of targets in each merged catalog.

Note

The last catalog listed in the table is a super-merge of all the preceding catalogs, i.e., a merge over all surveys and programs.

.. rst-class:: columns

File Name File Size Number of Targets
fastspec-fuji-cmx-other.fits 11.2 MB 2,771
fastspec-fuji-special-dark.fits 140 MB 35,649
fastspec-fuji-sv1-backup.fits 15 MB 3,683
fastspec-fuji-sv1-bright.fits 506 MB 126,678
fastspec-fuji-sv1-dark.fits 942 MB 235,942
fastspec-fuji-sv1-other.fits 136 MB 34,152
fastspec-fuji-sv2-backup.fits 599 KB 107
fastspec-fuji-sv2-bright.fits 186 MB 46,510
fastspec-fuji-sv2-dark.fits 211 MB 52,781
fastspec-fuji-sv3-backup.fits 6.41 MB 1,564
fastspec-fuji-sv3-bright.fits 1.04 GB 265,325
fastspec-fuji-sv3-dark.fits 2.32 GB 592,441
fastspec-fuji.fits 5.5 GB 1,397,603

The following table summarizes the number of QSO targets whose redshift has been updated using the procedure documented :ref:`here<qso redshifts>`.

.. rst-class:: columns

Catalog Number of Objects Number with Corrected Redshifts
fastspec-fuji-cmx-other.fits 2,771 56
fastspec-fuji-special-dark.fits 35,649 313
fastspec-fuji-sv1-backup.fits 3,683 100
fastspec-fuji-sv1-bright.fits 126,678 65
fastspec-fuji-sv1-dark.fits 235,942 3,810
fastspec-fuji-sv1-other.fits 34,152 170
fastspec-fuji-sv2-backup.fits 107 0
fastspec-fuji-sv2-bright.fits 46,510 8
fastspec-fuji-sv2-dark.fits 52,781 1,029
fastspec-fuji-sv3-backup.fits 1,564 0
fastspec-fuji-sv3-bright.fits 265,325 133
fastspec-fuji-sv3-dark.fits 592,441 3,444
fastspec-fuji.fits 1,397,603 9,128

The following tables document the code versions and environment variables used to produce this VAC. For details regarding the revision history of FastSpecFit, please see the change log.

Note that the tagged dependencies can be retrieve from any FITS file with the following bit of code:

import fitsio
from desiutil.depend import Dependencies
codever = Dependencies(fitsio.read_header('/path/to/fastspecfit/file.fits, ext=0))
for codename, version in codever.items():
    print(codename, version)
.. rst-class:: columns

Software Package Version(s)
python 3.10.8
numpy 1.22.4
scipy 1.8.1
astropy 5.2.1
yaml 6.0
matplotlib 3.6.2
fitsio 1.1.8
desiutil 3.4.2
desispec 0.60.2
desitarget 2.7.0
desimodel 0.19.0
speclite 0.17
fastspecfit 2.5.0
.. rst-class:: columns

Environment Variable Value
DESI_ROOT /dvs_ro/cfs/cdirs/desi
DUST_DIR /dvs_ro/cfs/cdirs/cosmo/data/dust/v0_1
FPHOTO_DIR /dvs_ro/cfs/cdirs/desi/external/legacysurvey/dr9
FTEMPLATES_DIR /dvs_ro/cfs/cdirs/desi/science/gqp/templates/fastspecfit
FTEMPLATES_FILE ftemplates-chabrier-1.3.0.fits (see README.txt)
FPHOTO_FILE /global/common/software/desi/perlmutter/desiconda/20230111-2.1.0/code/fastspecfit/2.5.0/lib/python3.10/site-packages/fastspecfit/data/legacysurvey-dr9.yaml
EMLINES_FILE /global/common/software/desi/perlmutter/desiconda/20230111-2.1.0/code/fastspecfit/2.5.0/lib/python3.10/site-packages/fastspecfit/data/emlines.ecsv

In this section we briefly document issues or problems which were identified with the VAC after its final release, and provide additional details regarding previous versions of this VAC.

Please see the change log for a record of what code and data model changes have occurred since these versions were released and to report additional problems or to request new features please open a ticket.

  • Release date: January 2024
  • FastSpecFit version: 2.5.0
  • Templates: ftemplates-chabrier-1.3.0.fits (see README.txt).
  • Notes:
    • Several updates to the spectrophotometric templates aimed at addressing the stellar mass bias identified in issue/#159 (see PR/#166):
      • Templates are now just solar metallicity (previously 0.1, 1, and 1.6 times solar).
      • Five age bins now (vs 8 previously).
      • Expanded velocity dispersion grid (new measurable maximum value is now 475 km/s).
    • Correction to how the light-weighted ages, dust attenuations, and SFRs were being computed.
    • When fitting the broad+narrow emission-line model, [OIII] 4959,5007 is now fitted separately and the narrow Balmer+helium+forbidden line-widths and velocity shifts are all tied together.
    • All known bugs fixed.
  • Known issues:
    • None at this time.
  • Release date: December 2023
  • FastSpecFit version: 2.4.3
  • Templates: ftemplates-chabrier-1.2.0.fits (see README.txt).
  • Notes:
    • Minor updates to spectrophotometric templates (expanded velocity dispersion grid; see PR/#158).
    • All known bugs fixed.
  • Known Issues:
    • Warning: Stellar masses are systematically higher (by 0.2-0.5 dex) compared to other methods, so they should be used with caution (see issue/#159). Similarly, star-formation rates and other SPS model parameters have not been fully validated.
  • Release date: August 2023
  • FastSpecFit versions: 2.4.1, 2.4.2
  • Templates: ftemplates-chabrier-1.1.0.fits (see README.txt).
  • Notes:
    • Minor updates to spectrophotometric templates.
    • Just two rounds of emission-line fitting, not three (see PR/#151).
    • Updated IGM attenuation coefficients (see PR/#136).
    • Major algorithmic updates related to how emission-line amplitudes, fluxes, and inverse variances are computed, including a bug fix which the emission-line model spectra were not being convolved with the resolution matrix (see PR/#137).
  • Known Issues:
    • Warning: Stellar masses are systematically higher (by 0.2-0.5 dex) compared to other methods, so they should be used with caution (see issue/#159). Similarly, star-formation rates and other SPS model parameters have not been fully validated.
    • Bug: Fluxes (and EWs) of lines which lie in the camera-overlap region are overestimated by a factor of 2 due to a bug handling the different pixel scale (fixed in PR/#157).
  • Release date: February 2023
  • FastSpecFit versions: 2.1.0, 2.1.1
  • Templates: ftemplates-chabrier-1.0.0.fits (see README.txt).
  • Notes:
    • Major update of underlying spectrophotometric templates.
  • Known Issues:
    • Bug: [OII] 7320,7330 doublet amplitude ratio incorrectly inverted (fixed in PR/#120).
    • Bug: Artificial redshift dependence in derived stellar masses due to age prior (fixed in PR/#132).
    • Bug: Emission-line subtracted Dn(4000) values incorrectly computed (fixed in PR/#135).
  • Release date: August 2022
  • FastSpecFit versions: 1.0.0, 1.0.1
  • Templates: SSP-CKC14z/v1.0
  • Notes & Known Issues:
    • First major release; many issues addressed in future releases.