43 4-minute lights plus calibration frames were stacked using ImagesPlus; other post-processing was with Photoshop CS2 plus Astronomy Tools plugin, SiriL, and PhotoScape X.

Messier 51, the Whirlpool Galaxy, is a spiral galaxy that is 31 million light years from Earth in the constellation Canes Venatici. NGC 5195, also known as Messier 51b, is the dwarf galaxy that is interacting with Messier 51. The two galaxies are connected by a dust-rich tidal bridge.