We have derived the albedo ( a ) and phase function asymmetry factor ( g ) of interstellar dust grains at 1100 Å using archival Voyager observations of diffuse radiation in Ophiuchus .
We have found that the grains are highly forward scattering with g = 0.55 \pm 0.25 and a = 0.40 \pm 0.10 .
Even though most of the gas in this direction is in the Ophiuchus molecular cloud , the diffuse FUV radiation is almost entirely due to scattering in a relatively thin foreground cloud .
This suggests that one can not assume that the UV background is directly correlated with the total amount of gas in any direction .