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Welcome to SkyServer!

SkyServer is the catalog data access site for the Sloan Digital Sky Survey-III. From this site, you can view all the catalog data - measuremed quantities like positions and magnitudes - for all the stars, galaxies and quasars in the SDSS-III's Data Release 8.

Data Release 8 (DR8) is described at the DR8 page of the SDSS-III website. The area of sky covered by DR8 is shown on the DR8 Scope page.

Available Data

Data Release 8 includes many different kinds of data, accessible through either SkyServer or its companion site, the Science Archive Server. (DR8 is cumulative, including all the data included in previous releases.

DR8 contains the full imaging survey from the SDSS imaging camera. Future data releases will include only spectra, so DR8 includes all the released images of the entire Sloan Digital Sky Survey. SkyServer includes JPG images of the entire DR8 survey area; FITS image files of corrected frames in five imaging filters are available through the Science Archive Server.

DR8 also contains more than one million spectra from the original SDSS spectrograph, as part of the SDSS-I and SDSS-II, as well as data from the previous year of operations of the SEGUE-2 stellar spectra survey. SkyServer includes GIF previews and CSV files of all the spectra in DR8; FITS files of the spectra are available through the Science Archive Server.

SkyServer hosts all catalog data measured from the images and spectra as part of DR8. For more information on how the catalog data was derived, see the DR8 Algorithms page. To see what catalog data are available in the SkyServer database, see About the Database.

Data Access

SkyServer includes a number of Data Access tools. The tools vary from simple to complex and powerful. It is not necessary to learn every tool; just find one you are comfortable with and use it. If you find you are unable to do what you want using your favorite tool, return to this list and find another tool.

There are two general categories of tools: either you know what objects or positions you are looking for, or you are searching for data to match certain criteria. Once you know which category of tool you need, use the table below to decide which specific tool to use.

When you know what you are looking for...

When you have... ...and you need... ..then use
Position (RA/Dec) of an object or point in the sky An interactive image, with magnitudes of objects Navigate
SDSS ID or RA and Dec of a known object The object's image, spectrum (if available), and magnitudes Quick Look
SDSS ID or RA and Dec of a known object The object's image, spectrum (if available), and complete catalog data Explore
Position (RA/Dec) of an object or point in the sky A finding chart for telescope observations Finding Chart
Positions (RA/Dec) of several objects in SDSS-III Thumbnail images of each object Image List
IDs and positions (RA/Dec) from another survey or your own observations SDSS-III cross-matches for each of your objects Cross-ID

When you are searching for objects to meet certain criteria...

When your search criteria are... ...and you need... ..then use
Position (RA/Dec), for a radial or rectangular area SDSS-III object IDs and magnitudes Radial Search
Rectangular Search
Position (RA/Dec), magnitude, or redshift (if DR8 includes a spectrum for that object) Position (RA/Dec), magnitude, and/or redshift (if DR8 includes a spectrum for that object) Search Form
Position (RA/Dec), magnitude, object type, flags Any imaging or spectroscopic data Imaging Query (IQS)
Position (RA/Dec), magnitude, object type, flags, spectral classification, redshift Any imaging or spectroscopic data Spectroscopic Query (SQS)
Any parameters in the DR8 Schema Any DR8 data for up to 100,000 objects SQL Search
Any parameters in the DR8 Schema Unlimited amounts of data, with personal tables and analysis tools CasJobs batch query service


SkyServer and the DR8 web site include extensive help and documentation, covering all the ways to access the data. Good places to start are the Frequently Asked Questions and Glossary.

Cooking with Sloan is a series of guides showing you how to accomplish common astronomical tasks using SkyServer tools and SDSS data. SkyServer also offers an SQL Tutorial to help you search for data using the SQL programming language.

If you can't find the answer your question, contact the SDSS Help Desk.

Educational Resources

SkyServer is an excellent resource for educators, including K-12 teachers and college instructors. SDSS-III data provides a rich source of hands-on, inquiry-based activities for learning science at all levels. SkyServer includes many free resources that you can use and modify for your students. See the For Educators link to learn more about these free resources.

The SkyServer Educational Resources include many activities that teach a single science topic, such as the expanding universe or stellar spectra, using SDSS data. See the teacher guides for more information on how to use SkyServer educational resources in your classroom or lab section.

If you have questions about SkyServer educational resources, please E-mail the SkyServer education helpdesk!