  We present U, B, V, I broad-band, 6200A TiO medium-band and Halpha photometry
of the Orion Nebula Cluster obtained with the WFI imager at the ESO/MPI 2.2
telescope. The nearly-simultaneous observations cover the entire ONC in a field
of about 34x34 arcmin. They enable us to determine stellar colors avoiding the
additional scatter in the photometry induced by stellar variability typical of
pre-main sequence stars. We identify 2,612 point-like sources in I band, 58%,
43% and 17% of them detected also in V, B and U, respectively. 1040 sources are
identified in Halpha band. In this paper we present the observations, the
calibration techniques, and the resulting catalog. We show the derived CMD of
the population and discuss the completeness of our photometry. We define a
spectro-photometric TiO index from the fluxes in V, I, and TiO-band. We find a
correlation between the index and the spectral type valid for M-type stars,
that is accurate to better than 1 spectral sub-class for M3-M6 types and better
than 2 spectral subclasses for M0-M2 types. This allows us to newly classify
217 stars. We subtract from our Halpha photometry the photospheric continuum at
its wavelength, deriving calibrated line excess for the full sample. This
represents the largest Halpha star catalog obtained to date on the ONC. This
data set enables a full re-analysis of the properties of the Pre-Main Sequence
population in the Orion Nebula Cluster to be presented, in an accompanying
paper.
