The narrowband ultraviolet imaging experiment for wide-field surveys. I. Dust-scattered continuum

We report on the first results of NUVIEWS, a sounding rocket experiment designed to map the far-UV background in four narrow UV bands. This is the first imaging measurement of the UV background to cover a substantial fraction of the sky. In our first flight, we mapped one-quarter of the sky with similar to5'-10' imaging resolution. We present a map of the continuum background obtained in the 1740 Angstrom telescope and use a model based upon the multiple scattering approach of Witt, Friedman, & Sasseen and a three-dimensional stellar distribution to constrain the dust and other parameters. We find that the dust in the diffuse interstellar medium displays a moderate albedo (a = 0.45 +/- 0.05) and highly forward scattering phase function parameter (g = 0.77 +/- 0.1) over a large fraction of the sky, similar to the result found for a more restricted area by Witt, Friedman, & Sasseen. We have also discovered a significant variance from the model and shown that it is a natural property of the statistics of clouds with varying multiple scattering geometries. The coverage and quality of our data allows us to place simultaneous constraints on a, g, the extragalactic background (200 +/- 100 CU), a slant cosecant (airglow) contribution (similar to 200 CU), and an instrumental scattering component (40 +/- 30 CU).