This is truly exciting. I once used ultraviolet light to examine some illegible handwritten marginalia in a 16th-century book at the Folger Shakespeare Library. I never did decipher the marginalia, but I was struck by how vividly old scars on my hands lit up under the ultraviolet light.

If anyone is interested, the fragment from the Codex Vercellensis is a passage from the second chapter of Luke ("quia viderunt oculi mei salutare tuum" from verse 30 was the give-away for me).