I was working at the Allegheny Observatory of the University of Pittsburgh from 1986-1991 when I began photometry of astrometric reference stars used in the AO astrometry program. The purpose for the observations was to measure the spectroscopic paralaxes and the interstellar extinction towards the reference stars. We used UBVRI, DDO, and the Stromgren filters sets. You can download one of the papers here (itís 2 MB). Observations were done with the (at the time) KPNO #2 0.9-m telescope and the AO 0.76-m Keeler reflector. We did photometry of more than 300 reference stars.