I am trying to do exhaustive optical emission line analysis of some active galaxies using archival data. What are some of the publically available data archives from where one could obtain optical emission line data? I am new to this, and so far I've found the HST MAST Archives and SDSS DR16.
A few sources come to mind to add to MAST and Sloan.
Data releases from the SAMI Galaxy survey, which contain (or will eventually contain) emission line spectra for about 3500 galaxies. The papers for the first two releases can be found [here] and [here].
Another (smaller and older) dataset can be found at the Penn State Center for Astrophysics. It contains spectroscopy of KISS emission line galaxy candidates. The download links to the dataset are on the CASt page [here].
I'll continue to update if I find more of a substantial size, but I think this should expand what you have already quite a bit.