The SDSS-III APOGEE Spectroscopic Pipeline

Detailed descriptions of the APOGEE pipeline reduction steps are provided on other pages:

Here, we provide references to papers that give additional details, and a table of the files associated with that step of the pipeline that can be found in the SAS. These tables include links to the file format documentation (the "data model") and templates which can be used to generate SAS URLs for those files. The templates are in "C printf" format, and can be used in C, bash, Python, and many other languages to automatically generate URLs.

Most of the catalog data (but not the spectra themselves) have been loaded into the Catalog Archive Server (CAS) database. Users are often better off obtaining SDSS data through a carefully constructed CAS query than they are downloading the data files from the SAS. Simple queries can be used to select just the objects and parameters of interest, while more complex queries can be used to do complex calculations on many objects, thereby avoiding the need to download the data on them at all.

APOGEE Raw Data Collection

SAS files generated in spectroscopic data collection
File Type	in/out	Description	URL format	format parameters
Log file	out	records exposures collected on a night	Not public
apR	out	raw spectroscopic data frames	sdss/spectro/data/%d/apR-%c-%08d.apz	mjd, detector (a,b,or c), exposure id

APOGEE Spectroscopic Data Reduction

Visit reduction pipeline (apred)

References: Nidever et al., in prep

The apred pipeline reads science and calibration exposures from the spectrographs, reduces and calibrates the science exposures, extracts the one dimensional spectra from the two dimensional exposures, corrects for sky emission and telluric absorption, stacks multiple dithered exposures into well-sampled spectra, and produces corresponding masks and noise estimates.

SAS files used or generated by the apred pipeline
File Type	in/out	Description	URL format	format parameters
apPlan	in	the apred processing plan	sdss/spectro/redux/%d/%04d/apPlan-%04d-%05d.par	rerun, plate, plate, mjd
plPlugMapM	in	records which fiber corresponds to which hole in a plate (and therefore objects, and what coordinates on the sky)	Not public
apR	in	raw spectroscopic data frames	sdss/apogee/data/%d/apR-%c-%08d.apz	mjd, chip (a, b, or c), exposure id
apCFrame	out	calibrated spectra for a single CCD and exposure	sdss/apogee/redux/%s/plates/%04d/%05d/apCFrame-%c-%08d.par	apred_vers, plate, mjd, chip (a, b, or c), exposure id
apPlate	out	the 300 combined flux- and wavelength-calibrated spectra over all exposures (potentially spanning multiple nights) for a given mapped plate	sdss/apogee/redux/%s/%04d/apPlate-%04d-%05d.fits	run2d, plate, plate, mjd
apVisit	out	thecombined flux- and wavelength-calibrated spectra over all exposures (potentially spanning multiple nights) for a given object on a given plate/MJD	sdss/spectro/redux/%s/%04d/apVisit-%04d-%05d-%03d.fits	run2d, plate, plate, mjd

Stellar combination pipeline (apstar)

APOGEE Stellar Parameters and Chemical Abundances Pipeline (aspcap)

References: Garcia-Perez et al, Mezsaros et al., Shetrone et al.

The ASPCAP stellar parameters pipeline produces a number of files, stored together:

SAS files used or generated by the ASPCAP pipeline
File Type	in/out	Description	URL format	format parameters
aspcapField	out	ASPCAP stellar parameters ([Fe/H], log g, etc.)	sdss/apogee/%s/%s/%s/%s//aspcapField-%04d.fits	APRED_VERS, APSTAR_VERS, ASPCAP_VERS, RESULTS_VERS, LOCID
aspcapStar	out	ASPCAP stellar parameters	sdss/apogee/%s/%s/%s/%s/LOCID/aspcapStar-%s-%04d.fits	APRED_VERS, APSTAR_VERS, ASPCAP_VERS, RESULTS_VERS, RESULTS_VERS, LOCID