  Velocity and density structure factors are measured over a hydrodynamic range
of scales in a horizontal quasi-2d fluidized granular experiment, with packing
fractions $\phi\in[10%,40%]$. The fluidization is realized by vertically
vibrating a rough plate, on top of which particles perform a Brownian-like
horizontal motion in addition to inelastic collisions. On one hand, the density
structure factor is equal to that of elastic hard spheres, except in the limit
of large length-scales, as it occurs in the presence of an effective
interaction. On the other hand, the velocity field shows a more complex
structure which is a genuine expression of a non-equilibrium steady state and
which can be compared to a recent fluctuating hydrodynamic theory with
non-equilibrium noise. The temporal decay of velocity modes autocorrelations is
compatible with linear hydrodynamic equations with rates dictated by viscous
momentum diffusion, corrected by a typical interaction time with the
thermostat. Equal-time velocity structure factors display a peculiar shape with
a plateau at large length-scales and another one at small scales, marking two
different temperatures: the "bath" temperature $T_b$, depending on shaking
parameters, and the "granular" temperature $T_g<T_b$, which is affected by
collisions. The two ranges of scales are separated by a correlation length
which grows with $\phi$, after proper rescaling with the mean free path.
