The mirror cleaning procedures are currently under review. There are
indications that washing of the mirrors provides better results than
CO
cleaning. However, CO cleaning does give improvements and
is much easier to perform. To get a proper idea of the relative
benefits of the cleaning methods and their frequency we intend to
start a monitoring programme of the zero-points in different
broad-band filters with ALFOSC and/or StanCam. Furthermore, we intend
to buy a new reflectometer that also measures scatter which is not
measured by the current meter. The idea is to correlate these
measurements and information about the weather (humidity, dust) with
the times of cleaning, and decide what is the best strategy to clean
the mirrors.