A parallel detection system has been added to the Wien Filter electron spectrometer on the dedicated scanning transmission electron microscope at IBM. The system uses an intensified diode array that is optically coupled to a single-crystal YAG screen by a vacuum window and an f/1.4-22 camera lens. The YAG screen shares the spectrometer image plane with energy selecting slits used for bright field STEM images and for single-channel energy loss analysis. Energy calibration to ±0.05 eV for scans over arbitrary energy ranges is accomplished by combining many parallel spectra having different energy centers. This process can remove channel gain variations, background variations, and nonlinear energy scale effects.