Page History
| Excerpt | ||
|---|---|---|
| ||
A description of the eBOSS data products hosted at MAST. |
| Panel | ||||||
|---|---|---|---|---|---|---|
| ||||||
This article describes the eBOSS data products hosted at MAST. On this page...
|
Summary
The primary data products from eBOSS survey are optical-wavelength (360- 1040 nm) spectra with a resolution of (λ/δλ)~2000 obtained using the BOSS spectrograph on the SDSS-2.5m telescope (Gunn et al. 2006) at Apache Point Observatory. SDSS observed using plug plates, aluminum plates with holes drilled corresponding to individual astronomical objects or random blank areas of sky. Each of the eBOSS plug plates covers a 3 degree diameter circle on the sky, and contained 1000 individual fibers resulting in 1000 spectra per plate. Targets for eBOSS include stars, galaxies, quasi-stellar objects, and blank sky.
An example eBOSS spectrum is shown in Figure 1, corresponding to the data in the "spec-4022-55352-0008.fits" and "spec-lite-4022-55352-0008.fits" spectrum files. For information on how to access and download eBOSS data through MAST, please refer to the Data Access page.
| Panel | ||||||||
|---|---|---|---|---|---|---|---|---|
| ||||||||
Figure 1 - Example eBOSS preview file, "spec-image-4022-55352-0008.png". |
Data Products at MAST
The SDSS eBOSS data products available at MAST are listed below. All eBOSS observations in MAST follow the naming scheme:
sdss_eboss_[PLATEID]-[MJD]-[FIBER4]
where all observation names start with the literal string "sdss_eboss_" and the other parameters are defined as:
- [
PLATEID]is the name of the plate used for that observation. This is typically a four or five-digit number between "3586" and "12547". - [
MJD]is the Modified Julian Date of the observation, - [
FIBER4]is the zero-padded number of the fiber used for that spectrum (a four digit number between "0001" and "1000").
An example eBOSS observation name in MAST would be, "sdss_eboss_12547-58928-0001". Observation names are all lowercase. Each observation represents one eBOSS target, and contains both spectrum products and the preview image files. More documentation on for all eBOSS data products can be found on the SDSS webpages describing the eBOSS survey and Getting Started with the SDSS spectra.
Full Spectrum Files
spec-{PLATEID}-{MJD}-{FIBER4}.fits- SDSS Data Model
The "full" spectrum files contain the combined spectrum, associated metadata, and the individual exposures.
Lite Spectrum Files
spec-lite-{PLATEID}-{MJD}-{FIBER4}.fits- SDSS Data Model
The "lite" spectrum files contain the combined spectrum and associated metadata but not the individual exposures.
| Note |
|---|
Note: The original SDSS names for the "spec-lite" files did not include the "-lite" extension, e.g. |
Preview Images
spec-image-{PLATEID}-{MJD}-{FIBER4}.pngspec-image-{PLATEID}-{MJD}-{FIBER4}.thumb.png- SDSS Data Model
The preview files and png images showing a preview of each eBOSS spectrum. An example eBOSS preview file is shown in Figure 1 above: the file is named "spec-image-4022-55352-0008.png" and it corresponds to the spectrum file "spec-4022-55352-0008.fits" and "spec-lite-4022-55352-0008.fits".
Catalog Files
The eBOSS survey provides several different catalog products containing various observation information and analysis properties for the eBOSS targets. Refer to the Data Access at MAST page for more information on how to search and download eBOSS data at MAST.
The catalog file types hosted at MAST are described below:
spAll
spAll-v5_13_2.fits- SDSS Data Model
The "spALL" catalog provides collated summary tables on the observations and data processing from eBOSS, including targeting information, spectroscopic classifications, and redshifts for every observation.
spAllLine
spAllLine-v5_13_2.fits- SDSS Data Model
The "spAllLine" catalog contains, for all spectra, the emission-line fits output from the original SDSS Spectro-1D analysis pipeline.
spPlate
spPlate-{PLATEID}-{MJD}.fits- SDSS Data Model
There is one "spPlate" catalog for each plate-MJD, containing the combined spectra and targeting information for all observations (1000 fibers) on a single plate.
spZall
spZall-{PLATEID}-{MJD}.fits- SDSS Data Model
The "spZall" catalogs, for each plate-MJD, containing the first, second, third, etc. best fit spectral redshift and classification measurements. The best fit is included in the spAll file. It is recommended to look at the second best fit here if best fit looks bad or has bad chi-squared.