Available Tools for Data Access

This page describes several tools for accessing the SDSS data: the Catalog Archive Server (CAS), the Science Archive Server (SAS), and direct data file access via rsync, wget, or http.

Catalog Archive Server (CAS)

Catalog data are available through SkyServer (also known as the Catalog Archive Server, or CAS). SkyServer also offers interactive tools to browse through SDSS images with links to associated spectra and catalog data about the objects on the images.

DR17 SkyServer
Interactive query tools for CAS
SkyServer Imaging Query Form
Simple image query form interface
SkyServer Spectroscopic Query Form
Simple spectroscopic query form interface
SkyServer Cross-ID
Match list of RA/Dec or IDs to imaging or spectroscopic catalog
Image List
Generate JPGs for a large set of objects
SkyServer Navigate
Point-and-click interface to JPG image of SDSS sky
SciServer Compute
Retrieve and analyze SDSS data using Python code running online
CAS SQL advanced user interface (use DR17 context)

The advanced DR17 CasJobs database interface gives you 500 MB or more of personal database space to select, analyze, and cross-identify SDSS data.

Science Archive Server (SAS)

While CAS is the primary interface to the catalog data, the Science Archive Server (SAS) is the primary interface to the original images and spectra. It provides tools to interactively view and download SDSS spectra, download images of SDSS fields, and generate mosaics of those fields.

In addition, SAS contains directory structures with the data in the original binary (FITS) and text file formats. To understand the directory structure and file formats, please see the imaging data, spectroscopic data, and infrared spectroscopy pages. To understand the way in which the SDSS organizes its data, see Understanding SDSS Imaging Data, Understanding SDSS Spectroscopic Data, Understanding SDSS Infrared Spectroscopy Data and Understanding SDSS Integral-Field Spectroscopic Data. Full details on the structure of all the data are in the detailed data model.

SAS Optical Spectra
Webapp to search-view-download optical spectra
SAS Infrared Spectra
Webapp to search-view-download infrared spectra
SAS Stellar Library Spectra
Webapp to search-view-download MaStar stellar library spectra
SAS Imaging Fields
Webapp to search-view-download SDSS field images
SAS Imaging Mosaic
Webapp to create larger-scale mosaic images
Web and Analysis Tool to visualize and analyse MaNGA integral-field spectroscopic data
Imaging catalogs
Directories of full image catalog files
BOSS_PHOTOOBJ data model
Corrected frames
Directories of full corrected image frames
BOSS_PHOTOOBJ/frames data model
Datasweep catalogs
Directories of reduced "sweep" imaging catalog data files
PHOTO_SWEEP data model
Optical Spectroscopy
Directories of optical spectra and catalogs.
Documentation, Legacy SPECTRO_REDUX data model, and BOSS_SPECTRO_REDUX data model
Infrared Spectroscopy
Directories of APOGEE spectra and catalogs
Documentation and APOGEE_REDUX data model
Stellar Library Spectra
Directories of MaStar Stellar Library spectra
Documentation and MaStar data model
IFU Spectroscopy
Directories of MaNGA spectra and catalogs
Documentation and MANGA_SPECTRO_REDUX data model

Note that both CAS and SAS will give you exactly the same catalog data. Essentially all of the data input into CAS is included in some form in the SAS. However, there are some small changes in naming convention (for example, "resolve_status" in SAS flat files is referred to as "resolveStatus" in CAS).

Direct file downloads

Expert users may need direct access to the data files themselves instead of webpage or database views of it. For this purpose, we provide the ability to directly download the files from SAS as described on the Bulk Download page.