This produced little change in the system emissivity from the April measurement. This was suspected to be a result of washing, which had been regularly carried out according to manufacturer's instructions, as the stored dichroic had evidently not deteriorated. The replacement coating was left rigorously unwashed. However in 1999 and into 2000 the emissivity was again creeping into the high teens of percent. A newly-coated replacement secondary had been installed in June and the reflectometer measurements showed that the primary mirror had not deteriorated to anything like this degree.
Figures showing recent emissivity behaviour are available here.