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The concept of the weekend didn't occur to the participants who, as far as they were concerned, today was day five not Saturday! Although the Yuan Li from the Chinese team did have the day off today. Breakfast was a sombre affair as we awoke to some clouds and it didn't look much better in the direction of Tuz Golu.

Cloudy skies	The ONERA bicycle-powered radiometer

When we arrived we were pleasantly surprised as there were relatively few clouds, however it didn't last as they did begin to bubble up throughout the morning. Even so the planned in-situ reference panel comparison went ahead, just after noon local time, and was repeated as the first measurement was done without the panel from ONERA as they were still measuring the 1 km x 1 km site, on bicycles!

Andrew Deadman measuring the CSIR panel	Flavio Ponzoni from INPE, Brazil, positioning his panel

The format of the panel comparison was that one radiometer, the one from NPL/ONERA was set up to view the NPL panel at nadir (normal to the surface). The participants panels were then measured in turn, with the NPL panel measured again after each of the participants panel. A similar process to the laboratory measurements. In order to minimise the effects of the changing sun zenith angle, the measurements were done close to local noon (where the changes are smallest) and quickly; the whole process took 15 minutes. In a further attempt to account for any  irradiance changes Derek Griffith from CSIR South Africa, offered to measure the irradiance using a cosine receptor he has for his ASD instrument. The irradiance was monitored throughout both the comparison measurement runs and encouragingly the initial results show that the irradiance varied by within ±1 % for most of the measurements.