Panel a: initial fiber position on the Moon (central black dot). The 1.5′′ fiber is centered on the central mountain of Tycho. The size of the dot is to scale. Telescope tracking errors are such that the fiber drifted out of the crater by the end of the 4-h time series. Panel b: light curve from the fiber exposure meter. Time on the x-axis is UT. The y-axis is counts per second. The various dips are due to clouds passing through.