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 ~5'-10' imaging resolution. We present a map of the continuum background obtained in the 1740 Å 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 (~200 CU), and an instrumental scattering component (40 ± 30 CU).