  We present far-ultraviolet observations of IC 63, an emission/reflection
nebula illuminated by the B0.5IV star gamma Cassiopeia, located 1.3 pc from the
nebula. Molecular hydrogen fluorescence was detected first in IC 63 by IUE and
later at shorter wavelengths by ORFEUS. Here we present Far Ultraviolet
Spectroscopic Explorer (FUSE) observations towards three locations in the
nebula, complemented by Hopkins Ultraviolet Telescope (HUT) data on the central
nebular position. In addition, we present a sounding rocket calibration of a
FUSE spectrum of gamma Cas. Molecular hydrogen fluorescence is detected in all
three FUSE pointings. The intensity of this emission as well as the
contributions from other species are seen to vary with position. The absolute
flux calibration of the sounding rocket data allows us to reliably predict the
radiation field incident on IC 63. We use these data to test models of the
fluorescent process. Our modeling resolves the perceived discrepancy between
the existing ultraviolet observations and achieves a satisfactory agreement
with the H_2 rotational structure observed with FUSE.
