Site Map

Data Access for SDSS DR9

Data Release 9 includes three types of data: images, spectra, and catalog data (parameters measured from images and spectra, such as magnitudes and redshifts). The SDSS web sites offer several different online data access tools, each suited to a particular need. The primary websites are:

Website Purpose DR9 Documentation (this site) Science Archive Server (SAS) DR9 front end with searchable interactive spectra and image mosaics Direct access to the DR9 data files for experts Detailed description of SAS directory structure and file formats and content Browsable interface to Catalog Archive Server (CAS) database and simple SQL queries; browsable sky images with associated spectra and catalog data. Advanced CAS database interface for all data releases Programmatic access to query or retrieve SDSS spectra (FITS or JSON formats)

These are described in more detail on the available tools page. The tables below provide links to the appropriate tools for various common tasks. If your question isn't addressed here, please take a look at the FAQ and/or tutorial help pages. Note that the getting started tutorials might be particularly helpful if you are new to SDSS-III.

If you are having difficulty connecting to any data server, please check the status page for announcements about planned outages.

Data from the SDSS-II Supernova Survey is not available in DR9, but is available in its entirety at the SDSS-II Supernova Survey website.


The SDSS has taken deep images of more than one-third of the entire night sky. You can view SDSS images online for any object or sky position in the survey area, and download images of SDSS fields as FITS files.

I need to... Tool to use
browse through sky images to look for interesting objects Navigate
create a finding chart for my telescope using SDSS imaging Finding chart
download FITS images for a specific SDSS field containing a given object or sky position Imaging (FITS) Field Search
download FITS images for many SDSS fields Bulk Imaging (FITS) Search
see thumbnail images for a list of objects Image List
see thumbnail images of objects that match my search criteria Image List


DR9 includes all spectra from SDSS-I/-II including SEGUE-I/-II, and all BOSS spectra through July 2011

I need to... Tool to use
know whether SDSS has measured a spectrum for my object Navigate
see the spectrum for my object Spectrum Search
get the spectrum for my object Spectrum Search
get 50,000 spectra See the bulk download documentation
retrieve SDSS spectra from within a script (e.g. Python, JavaScript...) SDSS-III API
Know which spectra data files are available Spectroscopic pipeline description
Understand the format of a specific data file Data Model

Catalog Data

Catalog data summarize quantities measured from the images and spectra such as magnitudes, redshifts, and object classifications. These are available either from the Catalog Archive Server (CAS) database, or as binary tables in FITS file format.

I need to... Tool to use
Find all objects which match some simple selection criteria SkyServer SQL Search
Perform a complicated CPU intensive catalog query CasJobs
Generate my own database with custom tables of a subset of the SDSS-III data CasJobs
Understand the CAS database schema Schema Browser
Download fits files with the catalog data See the bulk download documentation
Understand the format of a specific catalog data file Data Model