0.005 second exposure, SBIG ST-9E CCD with an H-alpha filter.
16" f/10 schmidt-cassegrain telescope plus a 2x barlow lens.
On the southern edge of Mare Nectaris, is the very large, flooded crater, Fracastorius. Although the southern portions of the rim are still quite impressive, the northern rim has been breached by the lavas of the mare.