Mirror cleaning

Since the aluminisation the mirror has been CO$_2$ cleaned a few times, which until now has kept the reflectivity at the same level as that measured just after the aluminisation, indicating that there is no need yet for a washing of the mirror. Especially, there was no change in the reflectivity of the mirror after a CO$_2$ cleaning following the forest fires close to the observatory which created a lot of smoke and ashes which might have affected the mirror.

Thomas Augusteijn 2006-02-02