SDSS (Sloan Digital Sky Survey)

Description Data Releases Seventeenth Data Release (SDSS DR17)Sixteenth Data Release (SDSS DR16)Estimated stellar masses in SDSS DR12 Galaxy Properties for DR8 spectra from MPA-JHU Data Access Acknowledgments

Sloan Digital Sky Survey (SDSS)

Description

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. We also host the galspecline_dr8 table from SDSS DR13.

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.

Data Releases

This section describes the main tables of the last two SDSS data releases that are hosted at Data Lab (besides the crossmatch tables mentioned above).

Seventeenth Data Release (SDSS DR17)

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

For further description of their latest release SDSS DR17, visit the SDSS.org site (http://www.sdss.org/dr17/).

Sixteenth Data Release (SDSS DR16)

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)
Table	Description
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

For further description of SDSS DR16, visit the SDSS.org site (http://www.sdss.org/dr16/).

Estimated stellar masses in SDSS DR12

The sdss_dr12.stellarmass_granada, sdss_dr12.stellarmass_portsmouth, and sdss_dr12.stellarmass_wisconsin tables contain estimated stellar masses for galaxies using several different models for each object.

sdss_dr12.stellarmass_granada
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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

Galaxy Properties for DR8 spectra from MPA-JHU

The sdss_dr8.galspecinfo, sdss_dr8.galspecline, sdss_dr8.galspecindx, and sdss_dr8.galspecextra tables contain the "galSpec" galaxy properties from MPA-JHU. These properties are deprecated in favor of the Wisconsin, Portsmouth, and Granada team analyses of the same data, but are provided in DR17 for comparison.

They refer to this set of line measurements as the MPA-JHU measurements, after the Max Planck Institute for Astrophysics and the Johns Hopkins University where the technique was developed. The Galspec product provided by the MPA-JHU group is based on the methods of Brinchmann et al. 2004, Kauffmann et al. 2003, and Tremonti et al. 2004. These have been run on previous SDSS data releases and the catalog has been made publicly available since DR4, and has been included in the SDSS data release since DR8.

They provide MPA measurements for all objects that "idlspec2d" calls a galaxy in rund2=26 (used for the DR7 plates). This code has not been run on the new SEGUE-2 plates in run2d=103 and 104 or on any BOSS spectra. They briefly describe the technique on their SDSS website; details can be found in the papers referenced above.

SDSS DR8 Galaxy Properties Tables
Table	Description
galspecinfo	Gives basic information about each spectrum (see datamodel)
galspecline	Gives line measurements for each spectrum (see datamodel)
galspecindx	Gives Lick and other indices for each spectrum (see datamodel)
galspecextra	Gives some ancillary physical parameters for each spectrum (see datamodel)

Above: Approximate coverage of the SDSS (based on DR12. Credit: SDSS DR12)

Data Access

The SDSS data are accessible by a variety of means:

SPARCL

SPectra Analysis & Retrievable Catalog Lab (SPARCL) at NOIRLab's Astro Data Lab provides flexible access to spectra from large optical and near-infrared surveys. SPARCL has been designed and tested to support spectra from SDSS. The SPARCL client package is pre-installed in Data Lab and can also be installed in a user's local computing environment. See the How to Use SPARCL Jupyter Notebook.

Data Lab Table Access Protocol (TAP) service

TAP provides a convenient access layer to the SDSS catalog database. TAP-aware clients (such as TOPCAT) can point to https://datalab.noirlab.edu/tap, select the sdss_dr17 database, and see the database tables and descriptions. You can also view the SDSS tables and descriptions in the Data Lab table browser.

Data Lab Query Client

The Query Client is available as part of the Data Lab software distribution. The Query Client provides a Python API to Data Lab database services. These services include anonymous and authenticated access through synchronous or asynchronous queries of the catalog made directly to the database. Additional Data Lab services for registered users include personal database storage and storage through the Data Lab VOSpace.

The Query Client can be called from a Jupyter Notebook on the Data Lab Notebook server. Example notebooks are provided to users upon creation of their user account (register here), and are also available to browse on GitHub at https://github.com/astro-datalab/notebooks-latest.

Jupyter Notebook Server

The Data Lab Jupyter Notebook server (authenticated service) contains examples of how to access and visualize the SDSS catalog:

Acknowledgments

SDSS requests that the following be added to the acknowledgment section of any paper using data from the SDSS-IV.

Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss4.org.<p> SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, Center for Astrophysics | Harvard & Smithsonian (CfA), the Chilean Participation Group, the French Participation Group, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatório Nacional / MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.

Find out more about how to cite SDSS-IV and earlier phases of SDSS, as well as a LaTeX template at How to Cite SDSS.

If using the Astro Data Lab and/or SPARCL, please also include their respective acknowledgments as described below:

Acknowledgment of SPARCL used jointly with the Astro Data Lab

If you use SPARCL jointly with the Astro Data Lab platform (via JupyterLab, command-line or web interface) in your published research, include the text below in your paper:

This research uses services or data provided by the SPectra Analysis and Retrievable Catalog Lab (SPARCL) and the Astro Data Lab, which are both part of the Community Science and Data Center (CSDC) program at NSF National Optical-Infrared Astronomy Research Laboratory. NOIRLab is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the National Science Foundation.

If publishing in a AAS journal, also add the keywords: \facility{Astro Data Lab} and \software{SPARCL (Juneau et al. 2024)} and cite:

Juneau et al., "SPARCL: SPectra Analysis and Retrievable Catalog Lab", Conference Proceedings for ADASS XXXIII, 2024 https://doi.org/10.48550/arXiv.2401.05576

Acknowledgment of SPARCL

If you use SPARCL in your published research, please include the text below in your paper:

This research uses services or data provided by the SPectra Analysis and Retrievable Catalog Lab (SPARCL), which is part of the Community Science and Data Center (CSDC) program at NSF National Optical-Infrared Astronomy Research Laboratory. NOIRLab is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the National Science Foundation.

If publishing in a AAS journal, also add the keyword: \software{SPARCL (Juneau et al. 2024)} and cite:

Juneau et al., "SPARCL: SPectra Analysis and Retrievable Catalog Lab", Conference Proceedings for ADASS XXXIII, 2024 https://doi.org/10.48550/arXiv.2401.05576