Thanks, all; you're very kind.
Nice, Jeremy, but did we push the color saturation a bit?
We might well have done, Russ; but by a lot less than you'd think. The colours are really extraordinary for those few minutes each day when the sun is in the right place1. Anyway, I strolled round Peter Lik's shop in Las Vegas when I was there last week, and the experience has reset my views on where the saturation slider should be.
Peter, you may be right about the underside, as Russ observed.
Jeremy
1 When it's not in the right place, the arch is just dull. I took a few steps back while waiting for The Moment and snapped this with my iPhone (the unattended tripod in the middle is mine).