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:
The Sloan Digital Sky Survey Data Release 15 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 during SDSS-III (see SDSS surveys details pages). 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.
The spectroscopy data are available through the links to the SkyServer Quicklook which lets you visualize and download the spectra and through the SkyServer Spectroscopic Query Form 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).