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/dr16/apogee/spectro/aspcap/r12/l33

Summary Catalogs

Contents	File Name & Direct Link	Data Model
summative catalog containing all quantities for each combined spectrum	allStar-r12-l33.fits (3.2 Gb)	Data Model
"lite" summative catalog containing all quantities for each combined spectrum	allStarLite-r12-l33.fits (891 Mb)	Data Model
summative catalog containing quantities derived from each individual visit spectrum	allVisit-r12.l33.fits (1.6 Gb)	Data Model
catalog of Cannon stellar parameters and abundances	Not produced in DR16; Please see DR15 Data Access Documentation for details on how to retrieve these files.	DR15 Cannon Data Model

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/dr16/apogee/spectro/aspcap/r12/l33/TELESCOPE/FIELD/

The file name is constructed as:

aspcapStar-r12-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/dr16/apogee/spectro/redux/r12/stars/TELESCOPE/FIELD

The filename is constructed as:

 apStar-r12-APOGEE_ID.fits, asStar-r12-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/dr16/apogee/spectro/redux/r12/visit/TELESCOPE/FIELD/PLATE/MJD

The filename is constructed as:

 apVisit-r12-PLATE-MJD-FIBERID.fits or asVisit-r12-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

APOGEE File Name	Contents	SAS Path	Data Model
aspcapStar	Pseudo-continuum normalized, combined spectrum, with best matching synthetic ASPCAP spectrum, one file per object	/sas/dr16/apogee/spectro/aspcap/r12/l33/TELESCOPE/FIELD/aspcapStar-r12-APOGEE_ID.fits	Data Model
apStar -or- asStar	Combined spectrum, one file per object	/sas/dr16/apogee/spectro/redux/r12/stars/TELESCOPE/FIELD/FILE	Data Model
apVisit -or- asVisit	Individual visit spectrum, one file per visit	/sas/dr16/apogee/spectro/redux/r12/visit/TELESCOPE/FIELD/PLATE/MJD/filename	Data Model

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

DR16 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/dr16/apogee/target/

Targeting Field Summary Files

Summary File	Description	Data Model
apogee2Field -or- apogeeField	Summary file that contains information for all fields, such as central coordinates	Data Model
apogee2Design -or- apogeeDesign	contains information on the individual designs, or groups of stars, like color limits and cohort fiber allocations	Data Model
apogee2Plate -or- apogeePlate	contains information on the physical plates, such as drill angle	Data Model

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/dr16/apogee/target/ and the links provided below go to the proper sub-directory.

Targeting Input Files

Field File	Description	Data Model
apogee2Object	contains photometric and proper motion information on the candidate targets in the APOGEE-2 fields; one file for each field in the survey.	Data Model
apogeeObject	contains photometric and proper motion information on the candidate targets in the APOGEE-1 fields; one file for each field in the survey.	Data Model
apogee1mObject	contains photometric and proper motion information on the candidate targets in the APOGEE 1m fields; one file for each field in the survey.	Similar to apogeeObject

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.

Files Generated during Data Collection

TELESCOPE	Telescope	Location of Files
apo25m	Apache Point Observatory 2.5 meter	apogee/spectro/data/MJD
lco25m	Las Campanas Observatory 2.5 meter	apogee/spectro/data2s/MJD
apo1m	Apache Point Observatory 1.0 meter	apogee/spectro/data1m/MJD

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/dr16/apogee/spectro/redux/r12/visit/TELESCOPE/FIELD/PLATE/MJD/

Files used or created by apred for Visit Processing

File	input or output	File Description	Data Model
apPlan -or- asPlan	input	the apred processing plan	Data Model
apCFrame -or- asCFrame	output	calibrated spectra file for each chip of each exposure	Data Model
apPlate -or- asPlate	output	Summary file for all exposures of each chip containing the 300 combined flux- and wavelength-calibrated spectra	Data Model
apPlateSum -or- asPlateSum	output	Summary file with metadata for the objects with apPlate/asPlate files
apVisit -or- asVisit	output	for a given object on a given plate/MJD the combined flux- and wavelength-calibrated spectra for all exposures	Data Model
apVisitSum	output	Summary file with the derived parameters for objects with apVisit/asVisit files (no spectra)

Combined Spectra

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

 /sas/dr16/apogee/spectro/redux/r12/stars/TELESCOPE/FIELD

Files Created for Visit Combination

File	input or output	File Description	Data Model
apStar -or- asStar	output	Combined spectrum for an individual object.	Data Model
apStarLSF	output	one for each object	Data Model
apField -or- asField	output	Radial velocities and target information for all stars in a given field	Data Model
apFieldVisits	output	Table of individual visit RVs for a given field	Data Model

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/dr16/apogee/spectro/aspcap/r12/l33/TELESCOPE/FIELD/aspcapField-FIELD.fits

Files created by ASPCAP

File	input or output	File Description	Data Model
aspcapField	output	ASPCAP stellar parameters (logg, Teff, [M/H], etc.), normalized spectrum, and best fit spectrum for each stars in a given field.	Data Model

APOGEE tags each stage of its pipeline with specific version numbers that are then included in the file names and as tags in the allStar (or equivalent) summary file. DR16 uses the following reduction/configuration versions:

• APRED_VERSION:: r12
• APSTAR_VERSION:: stars
• ASPCAP_VERSION:: l33
• RESULTS_VERSION:: l33