SDSS data products

DR4 and other data releases

About DR4 explains the contents of this data release and its relation to other data releases (also see the SDSS data release schedule).

Data products overview

Images - using SDSS as your telescope

SDSS provides FITS image files of the corrected frames in five bands, a mask that records how each pixel was used in the imaging pipelines, 4 x 4 binned images of the corrected frames after detected objects have been removed, and "atlas" images, which include all significant pixels around each object. This page describes imaging frames, how to get them and related files from the survey archive, and how to work with them.

Object lists - using SDSS as your photometric catalog

The calibrated object lists are FITS tables containing positions, fluxes, and shapes of all objects detected at >5 sigma on the images. This page describes the lists, how to get them and related files from the archive, and how to work with them.

Spectra and spectroscopic parameters - using SDSS as your spectrograph

"2d" spectra: FITS files of the flux- and wavelength-calibrated, sky-subtracted spectra, with error and mask arrays and resolution at each pixel. 640 spectra per file.
"1d" spectra: FITS files with the calibrated spectra and error and mask arrays, redshift, spectral classification, and detected lines of each spectrum.

The page describes calibrated spectra, how to get them and related files from the archive, and how to work with them.

Tiling - using SDSS as your complete survey

"Tiling" means optimising the placement of spectroscopic tiles on the sky and assignment of spectroscopic fibers to targets in the spectroscopic survey. This section describes the tiling files, how to get them and related files from the archive, and how to characterise the survey's non-uniformity using them.

Other data products

These include astrometric calibrations, photometric calibrations, gif and postscript plots of spectra, and finding charts in postscript/jpeg/fits formats.

Value Added Data Products

The SDSS collaboration has created catalogs and other data products based on public survey data that are of general use.

IAU designations for SDSS objects

Use IAU designations in publications.

Data access

All data products are available from the data access page as fits images and tables from the Data Archive Server (DAS). All catalogs are also available through the Catalog Archive Server (CAS) which provides fast search capabilities.

Data model

The flat-file data model contains detailed descriptions of all data generated by the data processing. The SQL Schema Browser describes how data are stored in the Catalog Archive Server (CAS).

Data quality overviews

Imaging

There are various quality assurance algorithms for photometry, some of which consider each run in isolation, and some of which consider overlapping parts of different runs. With DR4, we make available the summary and single-run QA data and plots, which analyze the PSF, the difference between aperture and PSF magnitudes of stars, and the location of the stellar locus in color-color space. Details are available on the QA pages.

The following overviews cover the quality of other aspects of imaging.

Spectroscopy

SDSS Webmaster Last modified: Fri Jun 24 16:02:52 CDT 2005