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Sloan Digital Sky Survey at the CFA | |
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Introduction | 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 |
Making the database |
Outline of procedure to obtain and recreate the Sloan survey in starbase format. |
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