  We present new deep and accurate space (Advanced Camera for Surveys -- Wide
Field Planetary Camera 2 at the Hubble Space Telescope) and ground-based
(Suprime-Cam at Subaru Telescope, Mega-Cam at Canada-France-Hawaii Telescope)
photometric and astrometric data for the Local Group dwarf irregular IC10. We
confirm the significant decrease of the young stellar population when moving
from the center toward the outermost regions. We find that the tidal radius of
IC10 is significantly larger than previous estimates of $r_t \lesssim$ 10\min.
By using the $I$,\vmi\ Color Magnitude Diagram based on the Suprime-Cam data we
detect sizable samples of red giant (RG) stars up to radial distances of
18-23$'$ from the galactic center. The ratio between observed star counts
(Mega-Cam data) across the tip of the RG branch and star counts predicted by
Galactic models indicate a star count excess at least at a 3$\sigma$ level up
to 34-42\min\ from the center. This finding supports the hypothesis that the
huge H{\size{I}} cloud covering more than one degree across the galaxy is
associated with IC10 \citep{huchtmeier79,cohen79}. We also provide new
estimates of the total luminosity ($L_V\sim9\times$$10^7$ $L_\odot$,
$M_V$$\sim$-15.1 mag) that agrees with similar estimates available in the
literature. If we restrict to the regions where rotational velocity
measurements are available (r$\approx13'$), we find a mass-to-light ratio
($\sim$10 $M_\odot$ $L_\odot$) that is at least one order of magnitude larger
than previous estimates. The new estimate should be cautiously treated, since
it is based on a minimal fraction of the body of the galaxy.
