Deep U-B-V imaging of the Lockman Hole with the LBT. Observations and
  number counts
  We used the large binocular camera (LBC) mounted on the large binocular
telescope (LBT) to observe the Lockman Hole in the U, B, and V bands. Our
observations cover an area of 925 sq.arcmin. We reached depths of 26.7, 26.3,
and 26.3 mag(AB) in the three bands, respectively, in terms of 50% source
detection efficiency, making this survey the deepest U-band survey and one of
the deepest B and V band surveys with respect to its covered area. We extracted
a large number of sources (~89000), detected in all three bands and examined
their surface density, comparing it with models of galaxy evolution. We find
good agreement with previous claims of a steep faint-end slope of the
luminosity functions, caused by late-type and irregular galaxies at z>1.5. A
population of dwarf star-forming galaxies at 1.5<z<2.5 is needed to explain the
U-band number counts. We also find evidence of strong supernova feedback at
high redshift. This survey is complementary to the r, i, and z Lockman Hole
survey conducted with the Subaru telescope and provides the essential
wavelength coverage to derive photometric redshifts and select different types
of sources from the Lockman Hole for further study.
