Psiga seems to be a person named Patrick Murphy (based on the recent change history: https://sites.google.com/site/psigamp3/system/app/pages/rece...) and they've uploaded at least one other phosphor test such as this one from 2011: https://sites.google.com/site/psigamp3/phosphorsim-gettingcl...

They also uploaded something as recently as 2017 so it might be possible to reach out to them and get a response?

Not sure if that helps find / reach out to them but I can hope.