Left: MUSE image of a region in the Hubble Deep Field South integrated over the wavelength range 7000−7200 Å. The two circular apertures that were used for measurements of the noise are shown as green circles. The displayed version shows the full depth, 55 exposures corresponding to 27.4 h. We selected the apertures to be located in a region without any detectable objects. Right: improvement of the noise measured in the final cube as a function of the number of exposures, measured as the standard deviation across two circular areas without any objects. See text for more details.