CAMAL (the Camera for the Automatic Monitoring of Atmospheric Lines) is an instrument deployed on Mount Hopkins in one of the MINERVA telescope domes. When MINERVA is open and observing, CAMAL also works to monitor the precipitable water vapor (PWV) above the observatory by imaging bright stars through its three narrowband filters. One filter overlaps a water band that tracks flux changes due to water vapor absorption over the course of the night; it utilizes this to map stellar fluxes through its three bands to PWV.
For more info on CAMAL, check out the paper or send me an email.