Sharpless

The Sharpless catalogue is a collection of emission nebulae with strong HII regions. Created by American astronomer Stewart Sharpless in 1959, it includes 313 objects. It is often called Sharpless-2 to differentiate it from an earlier 1953 version with 142 objects. All Sharpless objects are located above -27º declination, making them visible from most of the Northern Hemisphere. Images are usually captured with narrow-band filters like H-alpha, HOO, or SHO.