Observations of the near and far ultraviolet background

Abstract

The diffuse ultraviolet radiation field is seen over the entire sky and is a tracer of both the hot (in the form of lines such as CIV and OVI) and cold component (in the form of interstellar dust or molecular hydrogen) of the interstellar medium. Observations over the last 40 years have been continually pushing the boundaries of the available instrumentation but are now bearing fruit in a much better definition of the radiation and an understanding of its constituents, both foreground, such as airglow or zodiacal light, and cosmic. I present a review of the current state of observations of the far and near ultraviolet background.