Measured magnitude across the umbra edge with UVES at 10 000 Å. The horizontal error bars are 20 arcsec long and represent the typical pointing error of the telescope. Vertically, the 2σ error bars are the magnitude errors given by the UVES pipeline and the evaluated error in the local Moon albedo. The solid line is the model from Eq. (4) fitted through the data with parameter a₃ set to the mean value of a₃ found for the HARPS data. The vertical dotted line marks the edge of the umbra following our definition.