<p>The <a href="https://www.sdss.org/dr15/spectro/" rel="noreferrer">Sloan Digital Sky Survey Data Release 15</a> contains over 4 million spectra of both galactic and extra-galactic origin from the multi-fiber spectrographs. Of these spectra, 0.7 million came from the original spectrographs during the SDSS-I/II Legacy Survey and the remainder from the upgraded spectrographs as part of the <a href="https://www.sdss.org/surveys/boss/" rel="noreferrer">BOSS survey</a> during SDSS-III (see <a href="https://www.sdss.org/surveys/" rel="noreferrer">SDSS surveys details pages</a>). These data went through an automatic pipeline that determined the redshift automatically (where the data quality was good enough) and the details of the process are given <a href="https://www.sdss.org/dr15/spectro/galaxy/" rel="noreferrer">here</a>. </p>

<p>The spectroscopy data are available through the links to the <a href="https://skyserver.sdss.org/public/en/tools/quicklook/quickobj.aspx" rel="noreferrer">SkyServer Quicklook</a> which lets you visualize and download the spectra and through the <a href="http://skyserver.sdss.org/dr15/en/tools/search/SQS.aspx" rel="noreferrer">SkyServer Spectroscopic Query Form</a> which lets you search for galaxies. (Try setting the 'Parameters to return' to 'typical' under the 'Spectroscopy' section' and setting the 'Classification=GALAXY' under the 'Spectroscopy constraints' section to only return objects that have been classified as galaxies). </p>

CC BY-SA 4.0
2019-06-20T20:01:35.780Z
The four million spectra include 1.5 million from BOSS and all the spectra from the original surveys with the original spectrographs, as well as other surveys like SEGUE.
Peter Erwin
CC BY-SA 4.0
2019-06-20T20:42:07.840Z
Thanks, good points, I've updated the text
astrosnapper
CC BY-SA 4.0
2022-04-24T07:41:59.113Z
Quicklook link is broken. Here is the updated one http://skyserver.sdss.org/dr17/VisualTools/quickobj and the new version for the Query Form http://skyserver.sdss.org/dr17/SearchTools/SQS
Chooi Je Qin
CC BY-SA 4.0
2019-06-20T14:54:12.733Z
2019-06-20T20:41:44.527Z
2019-06-20T20:41:44.527Z
astrosnapper
<p>I was wondering where spectra of galaxies at various redshifts are to be found. I'm looking for ones that can be used to find the recessional velocity of the galaxy and eventually the Hubble Constant. Here's one I found:</p>

<p><a href="https://i.sstatic.net/pL3Os.jpg" rel="noreferrer"><img src="https://i.sstatic.net/pL3Os.jpg" alt="Sample galaxy spectrum from 4000 to 9000 Angstroms, showing hydrogen alpha and oxygen lines"></a></p>

<galaxy><redshift><spectra><hubble-constant>
Where can I find a database of galactic spectra?
Pedro de Oliveira
# Where can I find a database of galactic spectra?

(Asked by: username_0 on 2019-06-20)

I was wondering where spectra of galaxies at various redshifts are to be found. I'm looking for ones that can be used to find the recessional velocity of the galaxy and eventually the Hubble Constant. Here's one I found:

[![Sample galaxy spectrum from 4000 to 9000 Angstroms, showing hydrogen alpha and oxygen lines](https://i.sstatic.net/pL3Os.jpg)](https://i.sstatic.net/pL3Os.jpg)

**Tags:** galaxy, redshift, spectra, hubble-constant

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## 1 answers

### Answer by username_1 on 2019-06-20. Score: 10 | Accepted answer

The [Sloan Digital Sky Survey Data Release 15](https://www.sdss.org/dr15/spectro/) contains over 4 million spectra of both galactic and extra-galactic origin from the multi-fiber spectrographs. Of these spectra, 0.7 million came from the original spectrographs during the SDSS-I/II Legacy Survey and the remainder from the upgraded spectrographs as part of the [BOSS survey](https://www.sdss.org/surveys/boss/) during SDSS-III (see [SDSS surveys details pages](https://www.sdss.org/surveys/)). These data went through an automatic pipeline that determined the redshift automatically (where the data quality was good enough) and the details of the process are given [here](https://www.sdss.org/dr15/spectro/galaxy/).

The spectroscopy data are available through the links to the [SkyServer Quicklook](https://skyserver.sdss.org/public/en/tools/quicklook/quickobj.aspx) which lets you visualize and download the spectra and through the [SkyServer Spectroscopic Query Form](http://skyserver.sdss.org/dr15/en/tools/search/SQS.aspx) which lets you search for galaxies. (Try setting the 'Parameters to return' to 'typical' under the 'Spectroscopy' section' and setting the 'Classification=GALAXY' under the 'Spectroscopy constraints' section to only return objects that have been classified as galaxies).

> **Comments:**
> **username_2**: The four million spectra include 1.5 million from BOSS and all the spectra from the original surveys with the original spectrographs, as well as other surveys like SEGUE.  
> **username_1**: Thanks, good points, I've updated the text  
> **username_3**: Quicklook link is broken. Here is the updated one http://skyserver.sdss.org/dr17/VisualTools/quickobj and the new version for the Query Form http://skyserver.sdss.org/dr17/SearchTools/SQS  

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