NYU Value-Added Galaxy Catalog
This file contains catalog information for SDSS spectra. The entries are basically copied from the file $VAGC_REDUX/sdss/sdss_spectro_catalog.fits. Entries with SDSS_SPECTRO_TAG==-1 have no spectrum in the SDSS.
All of the columns in this file are well explained at the SDSS spectro reduction website.
This file only contains matches to object_sdss_imaging objects. In order to access the full catalog, look in the file:
$VAGC_REDUX/sdss/sdss_spectro_catalog.fitsThe file object_sdss_spectro.fits has a column SDSS_SPECTRO_POSITION which yields the zero-indexed position in the full sdss_spectro_catalog.fits file.