In the optical path the camera is preceded by a seven-position filter wheel by Finger Lakes Instruments (FLI). The filter wheel is populated with UBVRI filters (ultraviolet, blue, visual [~ green], red, and near infrared) plus one clear filter (50 mm diameter) leaving one blank position. In front of the filter wheel is an FLI auto-focuser. As the outside temperature varies during a night, the focal plane moves in and out; the auto-focuser moves the camera to accommodate this temperature dependence. During the course of a year the nighttime temperature has ranged from 25° C to -25° C (77° F to -13° F) . With small seasonal adjustments in the spring and fall the auto-focuser accommodates the full 50° C (90° F) excursion in temperature.
The facility camera is an Apogee Alta U47-MB with a sensitive 1024x1024 pixel chip. Quantum efficiency is 0.92 at 0.6 mm (0.5 at 0.39 mm and 0.87 mm). With 13 μm pixels and the telescope focal length of 4064 mm, the chip scale is 0.66 pixels/arc second, resulting a square FOV of 11.3 arc minutes. This FOV easily contains the formal error radii for gamma-ray bursts produced, e.g., by the Swift/BAT instrument, which are routinely ~ 1.5 arc minutes in radius.