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Spectroscopic Data

There are several ways to get to the Spectroscopic Data. Below we list several ways for you to download spectra and catalogs, with the caveat that for large downloads we have additional information on the Bulk Download Page.

Alternative ways to access spectra and catalogs are through:

The SDSS optical spectra are split into several versions:

Optical Data

Catalogs of parameters derived from the daily coadded SDSS-V (Run2d: v6_2_1) optical spectra (described via its datamodel) can be directly downloaded via https://dr20.sdss.org/sas/dr20/spectro/boss/redux/v6_2_1/ or via the wget command (985 MB):

wget --spider https://dr20.sdss.org/sas/dr20/spectro/boss/redux/v6_2_1/summary/daily/spAll-v6_2_1.fits.gz

In addition, the field epoch (multi-MJD) coadds spectra have a parallel summary file that can be obtained via the wget command (891 MB):

wget --spider https://dr20.sdss.org/sas/dr20/spectro/boss/redux/v6_2_1/summary/epoch/spAll-v6_2_1-epoch.fits.gz

Finally, as subset of targets had all exposures coadded together in a set of custom allepoch coadds. Their summary file can be found via (95 MB):

wget --spider https://dr20.sdss.org/sas/dr20/spectro/boss/redux/v6_2_1/summary/allepoch/spAll-v6_2_1-allepoch.fits.gz

The SDSS I-IV (SDSS/BOSS/SEQUELS/eBOSS) optical spectra (Run2d: 26,103,104,v5_13_2) and matched to photometric data are documented on the optical spectra data page. These can be directly downloaded from the links on that page, or via wget commands. For example, to download the redshifts and classifications of all SDSS I-IV spectra (6.7 GB – Note: This is unchanged since DR17):

wget --spider https://dr17.sdss.org/sas/dr17/sdss/spectro/redux/specObj-dr17.fits

Or to get the SDSS (I-IV) associated photometric position-based matches (16 GB – Note: This is unchanged since DR17):

wget --spider https://dr17.sdss.org/sas/dr17/sdss/spectro/redux/photoPosPlate-dr17.fits

The stellar parameter (SSPP) results can be downloaded similarly (1.8 GB – Note: This is unchanged since DR12):

wget --spider https://dr20.sdss.org/sas/dr20/prior-surveys/sdss2-dr8-sdss/sspp/ssppOut-dr12.fits

Optical Spectra Per-Object Files

If you want a subset of the spectra, the most convenient form may be the spec files with one file per FIELD(PLATE)-MJD-CATALOGID(FIBER) containing the coadded spectrum, the redshift and classification fits, spectral line fits, and optionally the individual exposures which contributed to the coadd. These are located at:

Beneath each of those directories, the spectra are organized by plate/field in the form

DR18 and later Data Releases

FIELD/spec-FIELD-MJD-CATALOGID.fits

e.g., 15166/spec-15166-59251-04492065339.fits

Prior to DR18

PLATE/spec-PLATE-MJD-FIBER.fits

e.g., 3586/spec-3586-55181-0016.fits

To download these spectra in bulk, generate a list of spectra you wish to download in a text file of that format and then use wget:

  wget --spider -nv -r -nH --cut-dirs=7 \
-i speclist.txt \
-B https://dr20.sdss.org/sas/dr20/spectro/boss/redux/v6_2_1/spectra/daily/full/

Infrared Data

The SDSS Infrared Spectra (unchanged from DR19) are split into two versions:

  • SDSS-V MWM Spectra
    • https://dr20.sdss.org/sas/dr20/spectro/apogee/redux/1.3/
  • APOGEE-I/II Spectra
    • https://dr20.sdss.org/sas/dr20/spectro/apogee/redux/dr17/

Catalogs of the SDSS-V pipeline parameters derived from the pipeline products (described in their datamodels) can be downloaded via https://dr20.sdss.org/sas/dr20/spectro/apogee/redux/1.3/summary/ or via the wget commands (368MB and 909MB):

wget --spider https://dr20.sdss.org/sas/dr20/spectro/apogee/redux/1.3/summary/allStar-1.3-apo25m.fits

wget --spider https://dr20.sdss.org/sas/dr20/spectro/apogee/redux/1.3/summary/allVisit-1.3-apo25m.fits

Infrared Spectra

For NIR data, there are two types of spectra files apStar files and apVisit files, where the apStar contains all the visits of a given target. These can be downloaded from:

Analysis data: ASTRA

Starting in DR19, a new analysis pipeline was added that looks at both BOSS and APOGEE spectra for MWM. In DR20, two versions are included, a copy of 0.6.0 from DR19 that include the DR19 APOGEE spectra (see DR19 for details on this version) and a new 0.8.1 that only includes the DR20 BOSS spectra. The new DR20 0.8.1 version has analyzed the BOSS v6_2_1 spectra for all MWM targets through a number of different pipelines focused at different types of stars. Its summary files can be found in https://dr20.sdss.org/sas/dr20/spectro/astra/0.8.1/summary/ or via the wget command (854MB):

wget --spider -r -np -A "*.fits.gz" https://dr20.sdss.org/sas/dr20/spectro/astra/0.6.0/summary/

Repackaged Spectra

The DR20 (0.8.1) Astra Pipeline repackages the MWM spectra from only BOSS (v6_2_1), coadding all visits into a single file type with extensions for each instrument. Analogous to the Apogee products it produces a mwmStar and a mwmVisit file. These can be downloaded from:

IFU Data

SDSS has included two different IFUs Manga (SDSS-IV) and LVM (SDSS-V).

SDSS-V LVM Data

SDSS-V LVM data are described on the DR20 LVM data page. It includes information on the LVM data reduction pipeline (DRP), data analysis pipeline (DAP), and data visulatizon tools (LVMvis).

SDSS-IV Manga Data

SDSS-IV MaNGA IFU data are described on the DR17 MaNGA data page. You can also explore the data with Marvin.

Imaging Data

Images and derived catalog data are described on the imaging data page. You can use a SkyServer search or the file window_flist.fits file to identify which RERUN-RUN-CAMCOL-FIELD overlaps your region of interest. Then download the matching calibObj files (catalog data) or frame files (calibrated imaging data), e.g., for RERUN 301, RUN 2505, CAMCOL 3, FIELD 38, the r-band image is:

wget --spider https://dr20.sdss.org/sas/dr20/prior-surveys/sdss4-dr17-eboss/photoObj/frames/301/2505/3/frame-r-002505-3-0038.fits.bz2

and the associated catalog of identified galaxies for that patch of sky is:

wget --spider https://dr20.sdss.org/sas/dr20/prior-surveys/sdss4-dr17-eboss/sweeps/dr13_final/301/calibObj-002505-3-gal.fits.gz

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