Sloan Digital Sky Survey at the CFA
Data Release 7


A selection of the SDSS Data Release 7 (DR7) databases and associated files has been transferred to CFA. Each of these has been condensed by choosing a (we hope!) useful subset of the columns, and converted to Starbase tables, in the location /data/astrocat/SDSS-dr7.

Photometric Data

The PhotoPrim.db starbase file is a subset of the columns in the SDSS PhotoPrimary view of the entire photometry database. It has been sequentially indexed (i.e. physically sorted) by declination, (the dec column), into 1/10 degree bins and right ascension-sorted (ra column) within each declination bin. There are 356,683,542 rows in the database, out of over 585,000,000 in the full PhotoObjAll table. The local database file size is 285 GB.

One important improvement since DR6 is improved photometric calibration; see Ubercal for more information on the algorithm. For the DR7 installation, the Ubercal-calibrated magnitudes are now the default; the "ub_*" columns from the DR6 version have been eliminated.

Spectral Data

These databases are a subset of the SpecObjAll view of the SDSS spectral database. The SpecObjAll.db table contains all the rows (but not all the columns) of the SpecObjAll view, while SpecPhoto.db rows are from the SpecPhoto view, where the rows are SciencePrimary, i.e. it eliminates rows that are flagged as poor quality or are duplicates from earlier data releases or do not have specPrimary == 1. The two databases have been indexed in RA and Dec for quicker searching for spectra near a particular coordinate.

The spectral reductions are from the Princeton/Sloan database, who redid the Sloan reductions. There are 1,223,015 rows in the SpecPhoto.db table and 1,282,560 in the full set in SpecObjAll.db. These numbers from the Princeton data set are slightly different from those given by the Sloan server. The CFA database files are 489 MB and 512 MB, respectively.

Spectral Line Data

The SpecLine.db starbase database is created from the Princeton group's spectral line reductions of the SDSS spectral database. The database table has 22,480,122 rows, or 21 different line observations for 1,070,482 spectra. The file size is 2.7 GB.

Tools & Examples

getobjid - get thumbnail or finder image

getspecid - get spectra from local archive

footserver - Check if coordinate in SDSS footprint

sdssquery - query Sloan SkyServer from CFA

Making the database

Outline of procedure to obtain and recreate the Sloan survey in starbase format.