Iron VAC (DR1)¶
Overview¶
This page describes the Iron value-added catalog, which will be publicly
released as part of the DESI Data Release 1 (DESI/DR1) sometime in 2024
(exact date TBD).
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 Iron VAC can be accessed at any of the following links:
Data url |
https://data.desi.lbl.gov/desi/spectro/fastspecfit/iron/v2.0 |
NERSC (for collaborators) |
|
For more information regarding the content and organization of the VAC, please click on the following links:
Summary Statistics¶
The next two tables summarize the size and number of targets in each merged
catalog. The first table gives the sample in each survey and program, while the
second table combines all the individual programs into separate main,
sv, and special catalogs.
fastspec-iron-cmx-other.fits |
11.5 MB |
2,761 |
fastspec-iron-main-backup.fits |
61.3 MB |
15,163 |
fastspec-iron-main-bright.fits |
25.5 GB |
6,445,915 |
fastspec-iron-main-dark.fits |
39.9 GB |
10,074,406 |
fastspec-iron-special-backup.fits |
2.38 MB |
552 |
fastspec-iron-special-bright.fits |
175 MB |
43,261 |
fastspec-iron-special-dark.fits |
60.5 MB |
14,953 |
fastspec-iron-special-other.fits |
172 MB |
42,064 |
fastspec-iron-sv1-backup.fits |
14 MB |
3,331 |
fastspec-iron-sv1-bright.fits |
524 MB |
126,649 |
fastspec-iron-sv1-dark.fits |
965 MB |
233,158 |
fastspec-iron-sv1-other.fits |
141 MB |
34,112 |
fastspec-iron-sv2-backup.fits |
593 KB |
105 |
fastspec-iron-sv2-bright.fits |
193 MB |
46,486 |
fastspec-iron-sv2-dark.fits |
218 MB |
52,682 |
fastspec-iron-sv3-backup.fits |
6.45 MB |
1,524 |
fastspec-iron-sv3-bright.fits |
1.08 GB |
265,291 |
fastspec-iron-sv3-dark.fits |
2.4 GB |
592,165 |
fastspec-iron.fits |
73.4 GB |
17,994,578 |
The following table summarizes the number of QSO targets whose redshift has been updated using the procedure documented here.
Catalog |
Number of Targets |
Number with Corrected Redshifts |
|---|---|---|
fastspec-iron-cmx-other.fits |
2,771 |
63 |
fastspec-iron-special-dark.fits |
35,647 |
389 |
fastspec-iron-sv1-backup.fits |
3,683 |
119 |
fastspec-iron-sv1-bright.fits |
126,677 |
402 |
fastspec-iron-sv1-dark.fits |
235,881 |
4,656 |
fastspec-iron-sv1-other.fits |
34,150 |
372 |
fastspec-iron-sv2-backup.fits |
107 |
0 |
fastspec-iron-sv2-bright.fits |
46,510 |
151 |
fastspec-iron-sv2-dark.fits |
52,771 |
1,185 |
fastspec-iron-sv3-backup.fits |
1,564 |
32 |
fastspec-iron-sv3-bright.fits |
265,324 |
649 |
fastspec-iron-sv3-dark.fits |
592,394 |
5,973 |
fastspec-iron.fits |
1,397,479 |
13,991 |
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 |
3.3.1 |
desispec |
0.59.2 |
desitarget |
2.6.0 |
desimodel |
0.18.0 |
speclite |
0.16 |
fastspecfit |
2.4.1, 2.4.2 |
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-1.1.0.fits (see README.txt) |
FPHOTO_FILE |
/global/common/software/desi/perlmutter/desiconda/20230111-2.1.0/code/fastspecfit/2.4.1/lib/python3.10/site-packages/fastspecfit/data/legacysurvey-dr9.yaml |
EMLINES_FILE |
/global/common/software/desi/perlmutter/desiconda/20230111-2.1.0/code/fastspecfit/2.4.1/lib/python3.10/site-packages/fastspecfit/data/emlines.ecsv |
Notes & Known Issues¶
v2.0 (latest release)¶
Release date: August 2023
FastSpecFitversions:2.4.1,2.4.2Templates:
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).
v1.0¶
Release date: February 2023
FastSpecFitversions:2.1.0,2.1.1Templates:
ftemplates-chabrier-1.0.0.fits(see README.txt).Known Issues: