The emission from the inner ring around SN 1987A has been monitored by IUE,
and from those observations it is evident that the gas in the ring is
CNO-processed and thus circumstellar. In particular, the N/C and N/O
ratios are found to be 
and 
, respectively, and from
the evolution of the emission, a distance to the LMC of 
kpc is
derived. The size of the ring, and the density of its gas are estimated,
and compared to hydrodynamical simulations. The more recent (1997 and
onwards) evolution of the circumstellar emission is discussed in papers
concentrating on observations with HST/STIS. One of the findings is a hot
spot on the inside of the ring. The spot is most likely a region of the
ring which has already been overtaken by the circumstellar shock. Another
major finding is the broad (extending to nearly 20,000 km s 
)
Ly 
and H emission, which is evidence of the ejecta
interacting with an H II-region inside the inner ring. The geometry of
this region appears to correspond to the asymmetric structure derived from
radio emission. Diffuse Ly emission is also seen from supernova
debris inside the reverse shock. This emission may be due to excitation by
nonthermal particles accelerated by the shock. The ejecta and the ring
were also observed with HST/NICMOS, and images in He I 
10830 and
P were obtained. This is used together with optical images to
constrain the ionization and temperature of the gas. In order to prepare
for future HST/STIS and FUSE observations, the expected emission in narrow
lines from the H II-region was calculated. The strongest lines are
N V 1240 and O VI 1034, and the relative strength of
these lines probes the density of the gas. Together with the intensity of
the radio and X-ray emission, this can be used to model the structure of
the circumstellar gas, and hence the mass loss history of the progenitor.
In this analysis it is argued that the spectral type of the progenitor, Sk
-69.202, was not much earlier than B2 Ia, which corresponds well to the
pre-explosion classification.