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SDSS-III APOGEE parameter catalogs

Introduction

Parameters derived from APOGEE spectra are stored in several different locations:

The stars are selected in various ways, as described in our target selection pages. The manner in which each target was selected can be determined by looking at the APOGEE_TARGET1 and APOGEE_TARGET2 target bitmasks.

To test if the spectrum is "good", the STARFLAG should be checked. This flag is a bitmask, and each set bit has a particular meaning, described in , our bitmask documentation.

For ASPCAP results, the ASPCAPFLAG bitmask should be consulted to get some information about the expected quality of the stellar parameter results.

The examples below demonstrate how to use this information to obtain a set of objects.

Some examples of selecting APOGEE data from catalogs

Here we include a number of examples of getting APOGEE data from the catalogs. These examples assume that you are either logged into CASJobs and using the DR10 context, or have downloaded the APOGEE catalog files. In the latter, case we assume you are using IDL with the latest version of idlutils (v5_5_11 or later) or python with numpy and pyfits available (for example, if you have installed astropy).

Get all PLATES observed for a given LOCATION_ID

The APOGEE survey is conducted along a number of different lines of sight, each referred to as as a "field" or "location" (interchangeably). Each field has a name and an id number (LOCATION_ID). The stars in each field are observed multiple times on multiple visits, on different MJDs. These may involve one or more physical plug plates.

To find all the plate visits, one can search as follows (for LOCATION_ID 4105):

Get ASPCAP parameters and errors for all stars that were targeted as part of the main APOGEE survey.

The stellar parameters are available for all stars that had ASPCAP run on them. However, this includes some spectra known to be bad as well as stars targeted as part of ancillary programs of various sorts. Restricting to the good, main survey targets requires checking on target and catalog flags, as in the examples below:

Get parameters for all stars with [Fe/H] < -2 with no BAD FLAGS set

You can also select a subset of the stars based on their properties. This example finds a set of metal-poor stars, without any flags set indicating that the observations or analysis is bad.

Get ASPCAP parameters for stars flagged as known cluster members

In addition to selecting main survey targets, you can select other objects according how they were selected. This is an example of selecting objects chosen to be calibrator stars in clusters with known metallicities (APOGEE_CALIB_CLUSTER).

Get proper motions, JHK mag and errors, K-band extinction and radial velocities, for stars with RVs > 300 km/s (with no BAD flags for RVs).

There is photometric data associated with each target, including proper motions and other information. This example looks for such information for larger (heliocentric) radial velocity stars. It restricts to objects with good measured ASPCAP parameters. In CAS, this requires joining the apogeeStar and aspcapStar tables with the apogeeObject table, which has the target information. In the flat-files, enough of the target information is included in the allStar file in this case.

Get ASPCAP parameters and targeting flags for all stars with 1 degree of a cluster center.

CASJobs allows search for objects near any particular RA and Dec. The following example searches for ASPCAP parameters and targeting flags for the stars observed near M13. For completeness, we include the equivalent using IDL and idlutils.

Get individual RVs from individual visits, the ASPCAP parameters for the combined spectra for stars which have more than 6 visits.

Each star is visited several times, and in some case many times, in order to build up signal-to-noise and to detect radial velocity variations. The information about each visit to each star is in the apogeeVisit table. One could join this table with apogeeStar on apogee_id in order to literally find all visits to each star. However, in this example we are interested in just finding those visits that actually contributed to each combined spectrum. In this case, bad visits are excluded and commissioning data and survey data are kept separate (not combined). To find these stars, one may use the apogeeStarVisit table in CAS, or the array visit_pk which exists for each star in the allStar file. Alternatively, if you wanted to find all visits to a particular star, one could replace in the code below apogeeStarVisit with apogeeStarAllVisit and visit_pk with all_visit_pk.

Get APOGEE_IDs and SDSS/BOSS plate, mjd, fiberid for all stars that have both APOGEE and SEGUE spectra.

A small number of objects have been observed both in the optical with the SDSS and/or BOSS spectrographs and in the infrared with the APOGEE spectrograph. The examples below finds all matches between primary SDSS/BOSS spectra and APOGEE stars with a 3 arcsec tolerance for such cases (note that there are some cases where an entry in one catalog matches multiple entries in the other).

Get SDSS ugriz photometry, errors and flags, ASPCAP parameters for the APOGEE stars with b > 60

In addition to matching to the SDSS spectroscopy, you can also match to the SDSS photometric imaging data. In this case, we only give an example within CAS. To do this purely with flat files requires either downloading the full photometric catalog (about 3 Tbytes) or the "datasweep" files (about 300 Gbytes), both described in the imaging data access documentation, and constructing an efficient flat-file method to do the matching. For most purposes, CAS will be the right way to do this.

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