We observed the Hubble Deep Field South with the new panoramic integral field spectrograph MUSE that we built and just commissioned at the VLT .
The data cube resulting from 27 hours of integration covers one arcmin ^ { 2 } field of view at an unprecedented depth with a 1 \sigma emission line surface brightness limit of 1 \times 10 ^ { -19 } erg s ^ { -1 } cm ^ { -2 } arcsec ^ { -2 } , and contains \sim 90,000 spectra .
We present the combined and calibrated data cube , and we perform a first-pass analysis of the sources detected in the Hubble Deep Field South imaging .
We measured the redshifts of 189 sources up to a magnitude I _ { 814 } = 29.5 , increasing by more than an order of magnitude the number of known spectroscopic redshifts in this field .
We also discovered 26 Ly \alpha emitting galaxies which are not detected in the HST WFPC2 deep broad band images .

The intermediate spectral resolution of 2.3Å allows us to separate resolved asymmetric Ly \alpha emitters , [ O ii ] 3727 emitters , and C iii ] 1908 emitters and the large instantaneous wavelength range of 4500 Å helps to identify single emission lines such as [ O iii ] 5007 , \mathrm { H } \beta , and \mathrm { H } \alpha over a very large redshift range .
We also show how the three dimensional information of MUSE helps to resolve sources which are confused at ground-based image quality .

Overall , secure identifications are provided for 83 % of the 227 emission line sources detected in the MUSE data cube and for 32 % of the 586 sources identified in the HST catalog of .
The overall redshift distribution is fairly flat to z = 6.3 , with a reduction between z = 1.5 to 2.9 , in the well-known redshift desert .
The field of view of MUSE also allowed us to detect 17 groups within the field .
We checked that the number counts of [ O ii ] 3727 and Ly \alpha emitters are roughly consistent with predictions from the literature .
Using two examples we demonstrate that MUSE is able to provide exquisite spatially resolved spectroscopic information on intermediate redshift galaxies present in the field .

This unique data set can be used for a large range of follow-up studies .
We release the data cube , the associated products , and the source catalogue with redshifts , spectra and emission line fluxes .