Snowden (physics)

A Snowden is a unit of soft X-ray emissivity, equivalent to $$10^{-6}$$ ROSAT counts $$s^{-1} arcmin^{-2}$$. These units were chosen by S. L. Snowden when working with the ROSAT mission to create the ROSAT All-Sky Survey in order to make the surface brightness values fit into a two byte integer.