Fuji VAC (EDR)

Overview

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 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 previous versions.

Data Content & Access

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:

Summary Statistics

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.

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 here.

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

Code & Template Versions

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)

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

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

Notes & Known Issues

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.

v3.2 (latest release)

  • 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.

v3.1

  • 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.

v3.0

  • 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).

v2.0

  • 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).

v1.0

  • 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.