  We present eclipse maps of the two-dimensional thermal emission from the
dayside of the hot Jupiter WASP-43b, derived from an observation of a phase
curve with the JWST MIRI/LRS instrument. The observed eclipse shapes deviate
significantly from those expected for a planet emitting uniformly over its
surface. We fit a map to this deviation, constructed from spherical harmonics
up to order $\ell_{\rm max}=2$, alongside the planetary, orbital, stellar, and
systematic parameters. This yields a map with a meridionally-averaged eastward
hot-spot shift of $(7.75 \pm 0.36)^{\circ}$, with no significant degeneracy
between the map and the additional parameters. We show the latitudinal and
longitudinal contributions of the day-side emission structure to the eclipse
shape, finding a latitudinal signal of $\sim$200 ppm and a longitudinal signal
of $\sim$250 ppm. To investigate the sensitivity of the map to the method, we
fix the non-mapping parameters and derive an "eigenmap" fitted with an
optimised number of orthogonal phase curves, which yields a similar map to the
$\ell_{\rm max}=2$ map. We also fit a map up to $\ell_{\rm max}=3$, which shows
a smaller hot-spot shift, with a larger uncertainty. These maps are similar to
those produced by atmospheric simulations. We conclude that there is a
significant mapping signal which constrains the spherical harmonic components
of our model up to $\ell_{\rm max}=2$. Alternative mapping models may derive
different structures with smaller-scale features; we suggest that further
observations of WASP-43b and other planets will drive the development of more
robust methods and more accurate maps.
