[Radiance-general] How to simulate an artificial sun

[Kai Babetzki]

Dear Radiance Community,
I'm trying to compare measurements done in an artificial sky with 
radiance simulations. The problem I'm currently facing is how to model a 
lamp with a diameter of 70 centimeter that produces 20000 lux with an 
aperture of 1.5° (nearly parallel light) in Radiance?

Will be the only possibility to measure the existing lamp in a 
photogoniometer and use the ies format data files? Or are there other 
and maybe easier ways to simulate such an artificial sun lamp in 
Radiance? Some quick and dirty way would be nice!

Kind regards,
Kai