Sloan Digital Sky Survey (SDSS)
The Sloan Digital Sky Survey (SDSS) is one of the largest astronomical ground-based survey to date, observed with a fully dedicated telescope at Apache Point Observatory, in Southern New Mexico. SDSS includes photometric and spectroscopic observations, and started in 2000. In Data Release 17 (from Dec. 2021), the imaging portion covers 14,555 square degrees (around one third of the sky). The spectroscopic portion currently contains spectra for 5.8 million objects (4.8 million labeled as "useful") in the optical and more than 700 thousand in the IR. For more information on the SDSS DR17 statistics, please visit SDSS DR17 Scope.
Data Lab currently hosts all of the main tables with photometric and spectroscopic measurements from SDSS DR12, DR16, and DR17.
The sdss_dr17.specobj table has been crossmatched with all other datasets in Data Lab within a 1.5 arcsec radius, nearest neighbor only. These tables will appear with x1p5 in their name in our table browser. Example: sdss_dr17.x1p5__specobj__gaia_dr3__gaia_source.
These are the main tables of their last two SDSS data releases that are hosted at Data Lab (besides the crossmatch tables mentioned above):
| SDSS DR17 Database Main Tables | |
|---|---|
| Table | Description |
| photoplate | Full photometric catalog values |
| platex | Plate data for spectroscopic observations |
| segue1specobjall | View of specobjall that includes only SEGUE-1 spectra |
| segue2specobjall | View of specobjall that includes only SEGUE-2 spectra |
| seguespecobjall | View of specobjall that includes only SEGUE-1 + SEGUE-2 spectra |
| specobj | View of specobjall that have just the clean spectra. It excludes QA, sky and duplicates |
| specobjall | All measured values of spectra |
| SDSS DR16 Database Main Tables | |
|---|---|
| Table | Description |
| photoplate | Full photometric catalog values |
| platex | Plate data for spectroscopic observations |
| segue1specobjall | View of specobjall that includes only SEGUE-1 spectra |
| segue2specobjall | View of specobjall that includes only SEGUE-2 spectra |
| seguespecobjall | View of specobjall that includes only SEGUE-1 + SEGUE-2 spectra |
| specobj | View of specobjall that have just the clean spectra. It excludes QA, sky and duplicates |
| specobjall | All measured values of spectra | SDSS DR16 Database Value Added Catalogs (VAC) |
| dr16q | Quasar Catalog |
| dr16q_duplicates | Duplicates Quasar Catalog |
| dr16q_superset | Superset Quasar Catalog |
| dr16q_superset_duplicates | Superset Duplicates Quasar Catalog |
| elg_classifier | ELG classifer |
| sdssebossfirefly | Stellar population parameters measured of spectra |
| spiders_quasar | SPIDERS Quasar eRositas source |
Estimated stellar masses in SDSS DR12
sdss_dr12.stellarmass_granada
Stellar masses using FSPS models of
Conroy et al. (2009)
fit to SDSS photometry in ugriz. The fit is carried out on extinction
corrected model magnitudes that are scaled to the i-band c-model magnitude.
The assumed IMF is given by the "imf" column, the assumed star formation model is
given by the "model" column, and the inclusion dust extinction (or not) is given
by the "dust" column.
The "early-star-formation" star formation model restricts the assumption about when the star-formation in the galaxy could occur to within 2 Gyrs of the Big Bang. The "wide-star-formation" version allows an extended star-formation history.
sdss_dr12.stellarmass_portsmouth
Stellar masses using the method of
Maraston et al. (2009).
These fit stellar evolution models to the SDSS photometry, using the known redshifts.
The assumed IMF is given by the "imf" column, and the assumed evolution model is
given by the "model" column.
For passive stellar evolution, the star-formation model is an instantaneous burst stellar population whose age is fit for (with a minimum allowed age of 3 Gyrs). The population is 97% solar metallicity and 3% metal-poor, by mass. The "imf" column is set to "M09" for these models.
For star-forming galaxies, the star-formation model uses a metallicity (specified in the "metallicity" column) and one of three star-formation histories: constant, truncated, and exponentially declining ("tau"). The type, and relevant time scale, are given in the "SFH" column. The "age" listed gives the start time for the onset of star-formation in each model.
sdss_dr12.stellarmass_wisconsin
Stellar masses using the method of
Chen et al. (2012).
In this table, the best estimate of stellar mass is "mstellar_median".
Please use the "model" values to find the specific population synthesis model:
- model = "BC03" : Bruzual and Charlot (2003)
- model = "MS11" : Maraston and Stromback (2011)
Please use the "warning" values to check for data quality:
- warning = 0 : Results correspond to a best-fit PCA spectrum (no problems detected)
- warning = 1 : Target redshift too small (z < 0.05)
- warning = 2 : Target redshift too large (z > 0.80)
- warning = 3 : READSPEC cannot get wavelength vector
- warning = 4 : Available wavelengths all outside PCA coverage
- warning = 5 : Unable to project projection wavelength range
- warning = 6 : Unable to select projection wavelength range
- warning = 7 : Minimum chi^2 less than zero
- warning = 8 : Total of log mass PDF equal to zero
- warning = 9 : Total of velocity dispersion PDF equal to zero
Above: Approximate coverage of the SDSS (based on DR12. Credit: SDSS DR12):
