An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky
  Way Spectrophotometric Optical-through-Ultraviolet Extinction and Its
  R-Dependence
  We produce a set of 72 NIR through UV extinction curves by combining new
HST/STIS optical spectrophotometry with existing IUE spectrophotometry
(yielding gapless coverage from 1150 to 10000 Angstroms) and NIR photometry.
These curves are used to determine a new, internally consistent, NIR through UV
Milky Way Mean Curve and to characterize how the shapes of the extinction
curves depend on R(V). We emphasize that while this dependence captures much of
the curve variability, there remains considerable variation which is
independent of R(V). We use the optical spectrophotometry to verify the
presence of structure at intermediate wavelength scales in the curves. The fact
that the optical through UV portions of the curves are sampled at relatively
high resolution makes them very useful for determining how extinction affects
different broad band systems, and we provide several examples. Finally, we
compare our results to previous investigations.
