AGN/Galaxy Classification Value-Added Catalog for DESI DR1¶
IMPORTANT
The AGN/QSO VAC (agnqso) has been renamed the AGN/Galaxy Classification VAC (agngal) to better reflect its scope as it includes all galaxies regardless of possible AGN or QSO identification. All previous links remain functional but future versions and data releases will adopt the new name.
Overview¶
This value-added catalog (VAC) includes DESI DR1 galaxies and quasars from all targets (MWS, BGS, LRG, ELG, QSO as well as secondary targets; Myers et al. 2023).
The DESI Redrock pipeline (Bailey et al., in prep.) assigns a spectral type (SPECTYPE='STAR', 'GALAXY' or 'QSO') and a redshift (Z) to all spectra.
Then the machine-learning algorithm QuasarNet and the MgII post-processing pipeline are used to improve the quasar classification and redshift estimated (Chaussidon et al. 2023, Alexander et al. 2023).
Starting from a selection of extragalactic spectra (Z>0.001), this catalog includes classifications based on optical and ultraviolet diagrams using emission line measurements from FastSpecFit (Moustakas et al. 2023).
We use FastSpecFit v2.1, corresponding to the Iron value-added catalog released as the DESI First Data Release (DESI/DR1). The catalog also incorporates mid-infrared classifications
based on Tractor WISE photometry (Lang et al. 2016).
A more detailed description of this VAC will be provided in an upcoming manuscript. If you use this catalog for your research, please cite Juneau et al. (in preparation).
Emission-line and infrared diagnostics used in the catalog:¶
- [NII] BPT regions defined as:
- Kewley et al. (2001): Star-forming vs AGN
- Kauffmann et al. (2003): Star-forming vs Composite
- Schawinsky et al. (2007): Seyfert vs LINER
- Originally from Baldwin, Phillips & Terlevich (1981)
- [SII] BPT regions defined as:
- Law et al. (2021): Star-forming vs AGN
- Kewley et al. (2006): Seyfert vs LINER
- Original demarcations from Veilleux & Osterbrock (1987)
- [OI] BPT regions defined as:
- Law et al. (2021): Star-forming vs AGN
- Kewley et al. (2006): Seyfert vs LINER
- Original demarcations from Veilleux & Osterbrock (1987)
- WHAN diagram from Cid Fernandes et al. (2011)
- BLUE diagram from Lamareille et al. (2004) & Lamareille (2010)
- HeII BPT diagram from Shirazi & Brinchmann (2012)
- NeV diagnostic: detection of [NeV]λ3426 implies hard radiation with photon energies above 96.6 eV, indicating AGN (Schmidt et al. 1998)
- Mass-Excitation (MEx) diagram from Juneau et al. (2014)
- Kinematics-Excitation (KEx) diagram from Zhang & Hao (2018)
- WISE diagnostics cuts from Jarrett et al. (2011), Mateos et al. (2012), Stern et al. (2012), Assef et al. (2018), Yao et al. (2020), and Hviding et al. (2022)
Data Access¶
Data URL: https://data.desi.lbl.gov/public/dr1/vac/dr1/agngal
NERSC access:
/global/cfs/cdirs/desi/public/dr1/vac/dr1/agngal
Documentation¶
Tutorial¶
Along with the catalog file described below, we provide a tutorial Jupyter notebook, which needs to be used with two accompanying files:
01_how_to_use_agngal_catalog_dr1.ipynb: tutorial Jupyter notebook that reads in the VAC file and shows example usageagnmask.yaml: yaml file containing the definition of the bits for the bitmask columns of the VAC (AGN_MASKBITS,OPT_UV_TYPE,IR_TYPE)desiutil_bitmask.py: Python function based on desiutil.bitmask.py to handle the decoding of the bitmasks
These files are available at the following location: https://data.desi.lbl.gov/public/dr1/vac/dr1/agngal/v1.0/tutorial/
In addition to the Python notebook, the tutorial folder includes a pre-rendered HTML version for browsing.
Catalog File¶
agngal_desi.fits: Catalog of DESI DR1 galaxies and quasars with spectral and infrared classification diagnostics
Data Model¶
EXTENSIONS¶
| Number | EXTNAME | Ver | Type | Dimensions | Contents |
|---|---|---|---|---|---|
| HDU00 | PRIMARY | 1 | PrimaryHDU | () | Keywords only |
| HDU01 | AGNCAT | 1 | BinTableHDU | 1397603R x 35C | Table of DESI DR1 galaxies and quasars with classification diagnostics |
| HDU02 | AUXDATA | 1 | BinTableHDU | 1397603R x 58C | Table with Fastspecfit fluxes, stellar mass, and Tractor WISE fluxes |
HDU01¶
EXTNAME = AGNCAT
| Name | Type | Units | Description |
|---|---|---|---|
| TARGETID | int64 | - | Unique identifier for each object observed by DESI |
| SURVEY | char[7] | - | Survey name |
| PROGRAM | char[6] | - | DESI program type - BRIGHT, DARK, BACKUP, OTHER |
| HEALPIX | int32 | - | Healpix number |
| Z | float64 | - | Redshift from the FastSpecFit catalog |
| ZERR | float64 | - | Redshift error |
| ZWARN | int64 | - | Warning flags (0 is good) |
| SPECTYPE | char[6] | - | Spectral type of Redrock best fit template (e.g. GALAXY, QSO, STAR) |
| COADD_FIBERSTATUS | int32 | - | Bitwise-AND of input FIBERSTATUS |
| TARGET_RA | float64 | deg | Right Ascension in decimal degrees (J2000) |
| TARGET_DEC | float64 | deg | Declination in decimal degrees (J2000) |
| LS_ID | int64 | - | Legacy Surveys DR9 identifier from RELEASE, OBJID, BRICKID |
| MIN_MJD | float64 | d | MJD of the first exposure in coadded spectrum |
| MEAN_MJD | float64 | d | Mean of MJD of exposures in a coadded spectrum |
| MAX_MJD | float64 | d | MJD of the last exposure in coadded spectrum |
| COADD_NUMEXP | int16 | - | Number of exposures in coadd |
| COADD_EXPTIME | float32 | s | Summed exposure time for coadd |
| DESI_TARGET | int64 | - | DESI (dark time program) target selection bitmask |
| SCND_TARGET | int64 | - | SCND (secondary program) target selection bitmask |
| BGS_TARGET | int64 | - | BGS (bright time program) target selection bitmask |
| CMX_TARGET | int64 | - | Target selection bitmask for commissioning |
| SV1_DESI_TARGET | int64 | - | DESI (dark time program) target selection bitmask for SV1 |
| SV2_DESI_TARGET | int64 | - | DESI (dark time program) target selection bitmask for SV2 |
| SV3_DESI_TARGET | int64 | - | DESI (dark time program) target selection bitmask for SV3 |
| SV1_BGS_TARGET | int64 | - | BGS (bright time program) target selection bitmask for SV1 |
| SV2_BGS_TARGET | int64 | - | BGS (bright time program) target selection bitmask for SV2 |
| SV3_BGS_TARGET | int64 | - | BGS (bright time program) target selection bitmask for SV3 |
| SV1_SCND_TARGET | int64 | - | Secondary target selection bitmask for SV1 |
| SV2_SCND_TARGET | int64 | - | Secondary target selection bitmask for SV2 |
| SV3_SCND_TARGET | int64 | - | Secondary target selection bitmask for SV3 |
| AGN_MASKBITS | int64 | - | AGN selection bitmask, see below for more details. |
| OPT_UV_TYPE | int64 | - | AGN detailed optical/ultraviolet type information, see below for more details. |
| IR_TYPE | int64 | - | AGN detailed infrared type information, see below for more details. |
| MAIN_PRIMARY | logical | - | Boolean flag (True/False) for the primary coadded spectrum in main survey |
| SV_PRIMARY | logical | - | Boolean flag (True/False) for the primary coadded spectrum in SV (SV1+2+3) |
| ZCAT_PRIMARY | logical | - | Boolean flag (True/False) for the primary coadded spectrum in the zcatalog |
AGN_MASKBITS¶
- AGN_ANY (bit 0): any AGN classification is set
- RR (bit 1): Redrock determines this to be a QSO from template fitting
- MGII (bit 2): MgII Afterburner detects broad line
- QN (bit 3): QuasarNet reclassifies as a QSO
- QN_NEW_RR (bit 4): QuasarNet prompts different Redrock redshift
- QN_BGS (bit 5): QuasarNet reclassifies BGS target as a QSO
- QN_ELG (bit 6): QuasarNet reclassifies ELG target as a QSO
- QN_VAR_WISE (bit 7): QuasarNet reclassifies VAR_WISE_QSO target as a QSO
- BPT_ANY_SY (bit 10): At least one BPT diagnostic indicates SEYFERT
- BPT_ANY_AGN (bit 11): At least one BPT diagnostic indicates SEYFERT, LINER or COMPOSITE
- BROAD_LINE (bit 12): Lines with FWHN >=1200 km/s in Halpha, Hbeta, MgII and/or CIV line
- OPT_OTHER_AGN (bit 13): Rest frame optical emission lines diagnostic not BPT (4000-10000 ang) indicate AGN
- UV (bit 14): Rest frame UV emission lines indicate AGN
- WISE_ANY_AGN (bit 15): At least one infrared (WISE) colour diagnostic indicates AGN
OPT_UV_TYPE¶
- NII_BPT (bit 0): NII BPT diagnostic is available
- NII_SF (bit 1): NII BPT Star-forming
- NII_COMP (bit 2): NII BPT Composite
- NII_SY (bit 3): NII BPT Seyfert
- NII_LINER (bit 4): NII BPT LINER
- SII_BPT (bit 5): SII BPT diagnostic is available
- SII_SF (bit 6): SII BPT Star-forming
- SII_SY (bit 7): SII BPT Seyfert
- SII_LINER (bit 8): SII BPT LINER
- OI_BPT (bit 9): OI BPT diagnostic is available
- OI_SF (bit 10): OI BPT Star-forming
- OI_SY (bit 11): OI BPT Seyfert
- OI_LINER (bit 12): OI BPT LINER
- WHAN (bit 13): WHAN is available (Halpha and [NII])
- WHAN_SF (bit 14): WHAN Star-forming
- WHAN_SAGN (bit 15): WHAN Strong AGN
- WHAN_WAGN (bit 16): WHAN Weak AGN
- WHAN_RET (bit 17): WHAN Retired
- WHAN_PASS (bit 18): WHAN Passive
- BLUE (bit 19): Blue diagram available
- BLUE_AGN (bit 20): Blue diagram AGN
- BLUE_SLC (bit 21): Blue diagram Star-forming/LINER/Composite
- BLUE_LINER (bit 22): Blue diagram LINER
- BLUE_SF (bit 23): Blue diagram Star-forming
- BLUE_SFAGN (bit 24): Blue diagram Star-forming/AGN
- MEX (bit 25): Mass-Excitation diagram available
- MEX_AGN (bit 26): Mass-Excitation diagram AGN
- MEX_SF (bit 27): Mass-Excitation diagram Star-forming
- MEX_INTERM (bit 28): Mass-Excitation diagram Intermediate
- KEX (bit 29): Kinematics-Excitation diagram available
- KEX_AGN (bit 30): Kinematics-Excitation diagram AGN
- KEX_SF (bit 31): Kinematics-Excitation diagram Star-forming
- KEX_INTERM (bit 32): Kinematics-Excitation diagram Intermediate
- HEII_BPT (bit 33): He II BPT diagnostic is available
- HEII_AGN (bit 34): He II BPT AGN
- HEII_SF (bit 35): He II BPT Star-forming
- NEV (bit 36): Ne V is available
- NEV_AGN (bit 37): NE V AGN
- NEV_SF (bit 38): Ne V Star-forming
IR_TYPE¶
- WISE_W12 (bit 0): WISE W1 and W2 available
- WISE_W123 (bit 1): WISE W1, W2 and W3 available
- WISE_AGN_J11 (bit 2): WISE diagnostic Jarrett et al. 2011 is AGN (based on W1,W2,W3)
- WISE_SF_J11 (bit 3): WISE diagnostic Jarrett et al. 2011 is not an AGN (based on W1,W2,W3)
- WISE_AGN_S12 (bit 4): WISE diagnostic Stern et al. 2012 is AGN (based on W1,W2)
- WISE_SF_S12 (bit 5): WISE diagnostic Stern et al. 2012 is not an AGN (based on W1,W2)
- WISE_AGN_M12 (bit 6): WISE diagnostic Mateos et al. 2012 is AGN (based on W1,W2,W3)
- WISE_SF_M12 (bit 7): WISE diagnostic Mateos et al. 2012 is not an AGN (based on W1,W2,W3)
- WISE_AGN_A18 (bit 8): WISE diagnostic Assef et al. 2018 is AGN (based on W1,W2)
- WISE_SF_A18 (bit 9): WISE diagnostic Assef et al. 2018 is not an AGN (based on W1,W2)
- WISE_AGN_Y20 (bit 10): WISE diagnostic Yao et al. 2020 is AGN (based on W1,W2,W3)
- WISE_SF_Y20 (bit 11): WISE diagnostic Yao et al. 2020 is not an AGN (based on W1,W2,W3)
- WISE_AGN_H22 (bit 12): WISE diagnostic Hviding et al. 2022 is AGN (based on W1,W2,W3)
- WISE_SF_H22 (bit 13): WISE diagnostic Hviding et al. 2022 is not an AGN (based on W1,W2,W3)
HDU02¶
EXTNAME = AUXDATA
| Name | Type | Units | Description |
|---|---|---|---|
| TARGETID | int64 | - | Unique identifier for each object observed by DESI |
| SURVEY | char[7] | - | Survey name |
| PROGRAM | char[6] | - | DESI program type - BRIGHT, DARK, BACKUP, OTHER |
| LOGMSTAR | float32 | log(solMass) | Logarithmic stellar mass (h=1.0, Chabrier+2003 initial mass function) |
| FLUX_W1 | float32 | nanomaggy | WISE flux in W1 (AB) |
| FLUX_W2 | float32 | nanomaggy | WISE flux in W2 (AB) |
| FLUX_W3 | float32 | nanomaggy | WISE flux in W3 (AB) |
| FLUX_IVAR_W1 | float32 | nanomaggy^-2 | Inverse variance of FLUX_W1 (AB) |
| FLUX_IVAR_W2 | float32 | nanomaggy^-2 | Inverse variance of FLUX_W2 (AB) |
| FLUX_IVAR_W3 | float32 | nanomaggy^-2 | Inverse variance of FLUX_W3 (AB) |
| CIV_1549_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| CIV_1549_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| CIV_1549_SIGMA | float32 | km / s | Gaussian emission-line width |
| MGII_2796_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| MGII_2796_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| MGII_2796_SIGMA | float32 | km / s | Gaussian emission-line width |
| MGII_2803_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| MGII_2803_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| MGII_2803_SIGMA | float32 | km / s | Gaussian emission-line width |
| OII_3726_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| OII_3726_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| OII_3726_EW | float32 | Angstrom | Rest-frame emission-line equivalent width |
| OII_3726_EW_IVAR | float32 | 1 / Angstrom2 | Inverse variance of equivalent width |
| OII_3729_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| OII_3729_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| OII_3729_EW | float32 | Angstrom | Rest-frame emission-line equivalent width |
| OII_3729_EW_IVAR | float32 | 1 / Angstrom2 | Inverse variance of equivalent width |
| NEV_3426_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| NEV_3426_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HEII_4686_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| HEII_4686_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HBETA_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| HBETA_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HBETA_EW | float32 | Angstrom | Rest-frame emission-line equivalent width |
| HBETA_EW_IVAR | float32 | 1 / Angstrom2 | Inverse variance of equivalent width |
| HBETA_BROAD_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| HBETA_BROAD_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HBETA_BROAD_SIGMA | float32 | km / s | Gaussian emission-line width |
| HBETA_BROAD_CHI2 | float32 | Angstrom | Chi-squared of the line-fit |
| OIII_5007_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| OIII_5007_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| OIII_5007_SIGMA | float32 | km / s | Gaussian emission-line width |
| OI_6300_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| OI_6300_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HALPHA_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| HALPHA_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HALPHA_EW | float32 | Angstrom | Rest-frame emission-line equivalent width |
| HALPHA_SIGMA | float32 | km / s | Gaussian emission-line width |
| HALPHA_BROAD_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| HALPHA_BROAD_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| HALPHA_BROAD_SIGMA | float32 | km / s | Gaussian emission-line width |
| HALPHA_BROAD_VSHIFT | float32 | km / s | Velocity shift relative to Z |
| NII_6584_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| NII_6584_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| SII_6716_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| SII_6716_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
| SII_6731_FLUX | float32 | 10**-17 erg/(s cm2) | Gaussian-integrated emission-line flux |
| SII_6731_FLUX_IVAR | float32 | 10**+34 (s2 cm4) / erg2 | Inverse variance of integrated flux |
Contact¶
Contact Stephanie Juneau, Mar Mezcua or Becky Canning for questions about this catalog.
Change Log¶
v1.0¶
- 2026-02-25: Renamed VAC with same content (desi_agngal.fits)
- 2025-03-19: The initial catalog (desi_agnqso.fits)