  Observations of comet 67P/Churyumov-Gerasimenko were performed with MUSE at
large heliocentric distances post-perihelion, between March 3 and 7, 2016.
Those observations were part of a simultaneous ground-based campaign aimed at
providing large-scale information about comet 67P that complement the
ESA/Rosetta mission. We obtained a total of 38 datacubes over 5 nights. We take
advantage of the integral field unit (IFU) nature of the instrument to study
simultaneously the spectrum of 67P's dust and its spatial distribution in the
coma. We also look for evidence of gas emission in the coma. We produce a high
quality spectrum of the dust coma over the optical range that could be used as
a reference for future comet observations with the instrument. The slope of the
dust reflectivity is of 10%$/100$ nm over the 480-900 nm interval, with a
shallower slope towards redder wavelengths. We use the $\mathrm{Af\rho}$ to
quantify the dust production and measure values of 65$\pm$4 cm, 75$\pm$4 cm,
and 82$\pm$4 cm in the V, R, and I bands respectively. We detect several jets
in the coma, as well as the dust trail. Finally, using a novel method combining
spectral and spatial information, we detect the forbidden oxygen emission line
at 630 nm. Using this line we derive a water production rate of $1.5\pm0.6
\times 10^{26} \mathrm{molec./s}$, assuming all oxygen atoms come from the
photo-dissociation of water.
