I first saw it at about 2am. It was somewhat wider than shown here, a little bit bigger than the central peaks. It was a fabulous sight! I had the impression of a cathedral illuminated by a searchlight. By about 3am it was noticably narrower and the shadow of the little crater near the crater rim was nearly reaching to the central peaks; that small shadow is just barely visible in these images but it was quite obvious visually. By 3:30 the ray had been reduced to a thin line and by 3:45 it was gone.
The visual appearance was much more striking than these images would indicate. While the main ray is barely visible here, it was totally bright and obvious in the eyepiece.
This ray was discovered a few years ago by Dave Mitsky. His WWW page on the subject is interesting (and includes links to more info).
In my images lunar north is up and lunar east is left (mirror image of Rukl and Mitsky's images).