Value Added Catalogs

In addition to the primary SDSS-III photometry and spectroscopy, there are a few extra catalogs created by our collaborators that are distributed through the SAS.

SEGUE Value-Added Catalogs

This catalog provides the [α/Fe] ratios for SDSS and SEGUE stars from Lee et al. 2011. They are able to determine [α/Fe] abundance to an error less than 0.1 dex for stars with Teff between 4500 and 7500 K, log g between 1.5 and 5.0, [Fe/H] between -1.4 and +0.3, and S/N greater than 20. To accomplish this precision for a star with [Fe/H] < -1.4, a spectrum with S/N larger than 25 is required. The [
α/Fe] abundance ranges from -0.1 to +0.6.

These abundance measurements were tested on degraded ELODIE spectra, samples of high- (R=15,000) and medium-resolution (R=6,000) spectra, and six open and globular clusters.

Certain aspects of the SEGUE target selection algorithm, in addition to components of the survey’s design, will create observational biases in the sample. For example, SEGUE assigns the same number of spectroscopic fibers to each plate, regardless of the stellar density of the line-of-sight. As the stellar number density changes over the SEGUE footprint, investigations using the survey data must correct for this variable sampling to represent the true underlying Milky Way stellar distributions. In addition, some target types will require corrections for the color, magnitude, and/or proper motion selection.

Schlesinger et al. 2012 investigated these biases for cool dwarf stars in the SEGUE sample. This value-added catalog explains a technique to constrain and account for the observational biases in SEGUE. It also provides a series of weights that can be used to determine a complete, unbiased SEGUE G- and K-dwarf sample.

A list of identifiers for repeat spectroscopic observations of individual photometric targets in SEGUE. These are particularly useful for testing consistency of the SSPP.

An, Johnson, et al. (2008) have created a catalog of ugriz photometry of SDSS images near globular and open clusters. It is available from the cluster photometry catalog page of the SDSS classic website.

APOGEE Value-Added Catalogs

APOGEE red-clump catalog

Red Clump Catalogs

SAS location data model # of entries description
datamodel 10,341 objects DR11 RC catalog
datamodel 19,937 objects DR12 RC catalog

APOGEE’s target selection algorithm includes many red-clump (RC) stars in the APOGEE sample. A new method for identifying red-clump stars from spectrophotometric data and its application to the APOGEE data was presented in Bovy et al. (2014). This technique creates a very pure sample of red-clump stars with minimal contamination from red-giant-branch, secondary-red-clump, and asymptotic-giant-branch stars. The narrowness of the RC locus in color-metallicity-luminosity space allows distances to the stars to be assigned with an accuracy of 5%-10%. The purity is estimated to be about 95%.

The DR12 release includes both the DR11 version of the RC catalog, which was based on the first two years of APOGEE data and was the specific subject of Bovy et al. (2014), and the DR12 version of the catalog, which for all purposes supersedes the DR11 catalog. The DR11 catalog was used by Nidever et al. (2014) to study the distribution of abundances in the Milky Way disk.

The following table lists where the RC catalogs can be found on the SAS, where to find their data model, and some basic information about the catalog.

Accounting for Observational Biases in APOGEE

Section 4 of Bovy et al. (2014) described how to correct for observational biases due to the APOGEE target selection (for the whole (J-Ks)0 > 0.5 sample, not just the red-clump sample). Specifically, these are the biases due to the incomplete sampling of the available targets with (J-Ks)0 > 0.5 as a function of position on the sky and magnitude. Tools to correct for these biases are included in the apogee python package and extensive documentation on how to use this package is given on the package webpage. This selection-function code has been updated for DR12 (from the DR11 version described in the paper).

Section 5 of Bovy et al. (2014) discussed astrophysical biases due to the red-clump selection. Specifically, they investigated the biases in recovering the underlying age and metallicity distribution by only selecting red-clump stars. The RC selection preferentially select stars with ages between 1 and 4 Gyr and with metallicities > -0.9. Please consult section 5 of the paper above for full details. The apogee python package also has tools for working with the astrophysical biases.

BOSS Value-Added Catalogs

Large Scale Structure Galaxy Catalogs

The galaxy catalogs used in the DR10 large scale structure analyses (e.g., Anderson et al. 2013) are available in this location on the SAS. The files in the catalogs are described in the data model on The large-scale structure galaxy catalogs for DR11 and DR12 will be available on the SAS here (for DR11) and here (for DR12) when they become available.


Bovy et al. (2011) describes a technique for QSO target selection based on an extreme deconvolution method, which models the distribution of quasars and stars in color-color space, including their errors. The associated catalog is available here. The files in the catalog are described in the data model.

Photometric Redshift Distributions

Sheldon et al. (2011) have created a set of photometric redshift probability distributions for galaxies in the SDSS-III imaging data. The catalog is available here. The files in the catalog are described in the data model.

Galaxy Parameters

Catalogs of galaxy properties such as stellar masses, ages, stellar formation rates, and velocity dispersions are described on the Galaxy Products page.

QSO Catalog

The French Participation Group (FPG) to SDSS-III has produced a quasar catalog for each BOSS data release, described in detail in Pâris et al. 2013 and summarized in its latest form on the DR12Q algorithms page.