  We present here the spectrum of the galaxy companion to the z=4.7 quasar
BR1202-0725, in the optical range 6000-9000 A, corresponding to 1050-1580 A
rest-frame. We detect a strong Lya emission line at z=4.702, with an integrated
flux of 2x10^{-16} ergs/cm^2/s, and a UV continuum longward of the Lya emission
at a flux level of 3x10^{-19}ergs/cm^2/s/A. We fail to detect any CIV[1550]
emission with a 3 sigma upper limit of 3x10^{-17} ergs/cm^2/s $. We show that
the ratio between Lya and continuum intensity and the absence of a strong CIV
emission imply that the UV continuum radiation is the result of an intense
star-formation activity rather than of a reprocessing of the QSO flux. The
total estimated SFR of this z=4.7 star-forming region is about 15-54 Msun/yr,
depending on the IMF and the metallicity. The present data suggest that the Lya
emission has a velocity and spatial structure, with possible velocity
differences of about 500 km/s on scales of few kpc. These velocity patterns may
be a signature of collapsing or merging phenomena in the QSO and its
environment, as expected from current models of galaxy formation at high z.
