Optimized for time-series photometry, ProEM is a Princeton Instruments ProEM 1024B frame-transfer CCD detector. It features high quantum efficiency, external triggering from a Trimble GPS disciplined quartz oscillator, and optional electron-multiplication with high frame-rate. An automated filter wheel is fitted with Sloan (SDSS) and BG40 filters, and a manual filter wheel contains the Johnson/Bessel UBVRI set.