Ways to Access APOGEE Data

The tables below give the summary catalog files in FITS format on the SAS. These are found in the following directory: /sas/dr17/apogee/spectro/aspcap/dr17/synspec ( but see also this caveat )

Combined ASPCAP Spectrum:: aspcapStar

The pseudo-continuum normalized, combined spectrum, with best matching synthetic ASPCAP spectrum is recorded as one file per object in the aspcapStar file (data model). These are sorted by telescope and field, and can be found in the SAS using a path constructed as follows:

/sas/dr17/apogee/spectro/aspcap/dr17/synspec_rev1/TELESCOPE/FIELD/

The file name is constructed as:

aspcapStar-dr17-APOGEE_ID.fits

Where TELESCOPE, FIELD and APOGEE_ID are tags for each object that can be found in the allStar (or equivalent) summary file. Thus, to acquire this file, the user can build the URL from information in the allStar file.

Combined Spectrum:: apStar or asStar

The combined, RV-corrected spectra are recorded as one file per object in the apStar or asStar files, where apStar files are created for objects observed by the northern spectrograph and asStar files are created for objects observed by the southern spectrograph. These are sorted by telescope and field, and can be found in the SAS using a path constructed as follows:

 /sas/dr17/apogee/spectro/redux/dr17/stars/TELESCOPE/FIELD

The filename is constructed as:

 apStar-dr17-APOGEE_ID.fits, asStar-dr17-APOGEE_ID.fits

In the allStar (or equivalent) summary file, the filename for the combined spectrum is contained in the FILE tag. Thus, the user can build the URL from information contained in the allStar file.

Visit Spectrum:: apVisit or asVisit

The individual visit spectra are recorded as one file per visit in the apVisit or asVisit files. These are sorted by telescope, plate, MJD, and FIBERID. These files can be found in the SAS using a path constructed as follows:

 /sas/dr17/apogee/spectro/redux/dr17/visit/TELESCOPE/FIELD/PLATE/MJD

The filename is constructed as:

 apVisit-dr17-PLATE-MJD-FIBERID.fits or asVisit-dr17-PLATE-MJD-FIBERID.fits

This information can be acquired from the allVisit summary file, or in the VISITS tag of the allStar file. The VISITS tag contains a comma-separated list of the visit file names (without .fits appended).

Summary Table for Spectral Data

In addition to the summary catalogs and spectral data, all intermediate data products are also provided in the data release. Here the process is presented in the order of operations from targeting to final ASPCAP parameters and abundances. The pipeline code is available on github: sdss/apogee.

Targeting Field Summary Files

DR17 includes four types of files containing useful information on the stars (both targeted and non-targeted) in APOGEE fields and on the fields themselves, the designs, and the plates in which the targets are organized (see further details on this organizational structure in Zasowski et al. 2013 and Zasowski et al. 2017 ).

All summary files can be found in this directory: /sas/dr17/apogee/target/

In addition to these summary files, we also have the targeting input files that are used to design each plate. These are organized by survey and by field. They are contained in folders within /sas/dr17/apogee/target/ and the links provided below go to the proper sub-directory.

Observation Files

APOGEE raw image data are also available on the SAS. These are organized by telescope and MJD. To find these files, the user needs to have acquired the MJD for each visit in the allVisit file.

The raw data files are named apR-CHIP-EXPOSURE.apz for data taken by the northern spectrograph and asR-CHIP-EXPOSURE.apz for data taken by the southern spectrograph. The CHIP can be “a”, “b”, or “c”, where these letters correspond to the “red”, “green”, and “blue” APOGEE detectors, respectively.
The intermediate-level ap2D and ap1D files are available, but users should consult the data models (ap1D and ap2D), as well as the APOGEE reduction paper (Nidever et al. 2015) before using these files.

Visit Level Processing

The visit-level processing occurs in a code called apred and is described on Visit Reduction. These are are organized by telescope, FIELD, PLATE, and MJD. The file path is constructed as follows:

 /sas/dr17/apogee/spectro/redux/dr17/visit/TELESCOPE/FIELD/PLATE/MJD/

Combined Spectra

The visit spectra for each target are combined as described on the visit combination page. This occurs in the following directory:

 /sas/dr17/apogee/spectro/redux/dr17/stars/TELESCOPE/FIELD

APOGEE Stellar Parameters and Chemical Abundances Pipeline (ASPCAP)

The ASPCAP stellar parameters pipeline produces one intermediate file for each field that is then merged to form the allStar summary file. These “aspcapField” files are found in the aspcap directories sorted by telescope and field.

 /sas/dr17/apogee/spectro/aspcap/dr17/synspec_rev1/TELESCOPE/FIELD/aspcapField-FIELD.fits

• APRED_VERSION:: dr17
• APSTAR_VERSION:: stars
• ASPCAP_VERSION:: synspec
• RESULTS_VERSION:: OBSOLETE