Annu. Rev. Astron. Astrophys. 1991. 29: 89-127 Copyright © 1991 by Annual Reviews. All rights reserved

6.3 Diffuse Cosmic Ultraviolet Background Radiation

What is left? What is left is a background of ~ 400 units, which is present everywhere that has been observed at moderate and high galactic latitudes, and which is present everywhere from ~ 1216 to 3200 Å (and possibly beyond). This background is not present at wavelengths below ~ 1216 Å, where an upper limit of 100 units prevails.

This background, which may be extragalactic, may be spatially non uniform. The data of Murthy et al (82) suggest that, and there is an excellent observation by Martin & Bowyer (66) that also differs from the canonical value of 400 units.

I have suggested earlier a possible origin for such an extragalactic radiation. What is needed now, are precise new photometric and spectroscopic observations of this radiation, both to confirm it and to attempt to deduce its origin.