Good morning, Steve Smith;
Thank you for the information that the sun will be recalibrated this coming Thursday. I was beginning to worry about that. After all, the Johnson Curve was done back in 1948, and that data is at least 64 years old now.
And all of this time I have been using the "Sunny 16 Rule" without any thought at all to the accuracy of the spectral intensity of the light source.
Actually, the main thing that has been providing problems out here in Latte Land is the correction factor to apply as a function of the varying transmission characteristics of the different types of di-hydrogen oxide units floating in the air above us almost all of the time.