  We use data from the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra
X-ray Observatory to image the shell surrounding the pulsar B0540-69, and to
measure its spectral properties. Weak emission line features, notably of Fe, Mg
and Si, indicate that the shell is composed primarily of ambient material
heated by the blast wave. The shell emission in the east is faint and circular
in appearance, with a temperature and ionization age of approximately 5 keV and
10^10 cm^-3 s, respectively. The emission in the west is brighter and has a
more complex, distorted morphology, and is fitted with significantly lower
average temperatures and higher ionization ages. An image with photon energies
above 2 keV shows two hard arcs of emission located diametrically opposite each
other at the outer boundary of the remnant shell; the spectra from these
regions could include a substantial nonthermal component.
