A paper I wrote recently with ASU graduate student Mark Richardson has recently been accepted for publication in ApJ. Using my Starburst99/Mappings III models from 2010 combined with Mark’s new models of high-z galaxies with large ionization parameters, we calibrated a new diagnostic for ionization parameter in these galaxies, [NeIII]/[OII]. Right now the most common diagnostic for this is [OIII]/[OII], which we also re-calibrate; however, the [NeIII] diagnostic has the advantage of being insensitive to extinction effects and observable at short wavelengths (<4000A), making it usable for galaxies out to higher redshifts. Check out the manuscript to learn more about this new and useful diagnostic!