Help with crater identification...

Question for the group.
Last night I was observing the south east lunar limb (16"F5 Royce, 3mm Radian , 667X) and was observing a beutifil sunset over a large carter. Stupidly, I didnt consult an atlas and I am unfamiliar with many of the craters near the limb. This was just on the SE limb, very largte, viewed nearly edge on and with a central peak. Between 10am est and 12pm est the crater slowly filled with black and the central peak gradually dissapeared. It was absolutly spectacular, as if black water was rising and the peak submerging just before the level rose to the crater walls.
I am trying to identify which crater this was. It was roughly 250-300km across. Watching it slowly get swallowed up as the terminator crept from east to west was spectacular. Anyone know??
Joe

Joseph: Rükl's Atlas of the Moon indicates that the largest crater near the moon's southeastern rim is Petavius, which has a diameter of 177 km and a very prominent central peak. I suspect that's the one you saw and that you over-estimated the crater's diameter, since even Clavius -- which I believe is the biggest of the moon's craters (not including impact basins) -- is "only" 225 km in diameter.