Ultraviolet stellar fluxes from 1500 to 3200 Å were from February through August 1965 on OSO II. A 15-cm diameter Gregorian telescope with a stepped grating spectrophotometer provided flux measurements in ten adjacent 180 Å wide band passes.

By comparing fluxes of stars showing B-U color excesses smaller than 0.19 and larger than 0.26, an ultraviolet extinction curve has been derived, which agrees with others which have been published as far as the magnitude effect is concerned, but the shape differs somewhat, the slope at 1/λ = 3.8 μ−1 being somewhat greater than at 1/λ = 5.0 μ−1.

If the stars' fluxes are corrected for reddening, it is found that there is a good agreement between observation and models for stars earlier than B3, but that many of the later type stars have a residual apparently intrinsic reddening.