  As part of a large Hubble Space Telescope investigation aiming at reaching
the faintest stars in the Galactic globular cluster NGC 6752, an ACS/WFC field
was the subject of deep optical observations reaching magnitudes as faint as
V~30. In this field we report the discovery of Bedin I a dwarf spheroidal
galaxy too faint and too close to the core of NGC 6752 for detection in earlier
surveys. As it is of broad interest to complete the census of galaxies in the
local Universe, in this Letter we provide the position of this new object along
with preliminary assessments of its main param eters. Assuming the same
reddening as for NGC 6752, we estimate a distance modulus of (m-M)_0 =
29.70+/-0.13 from the observed red giant branch, i.e., 8.7 (+0.5 -0.7) Mpc, and
size of ~840x340pc, about 1/5 the size of the LMC. A comparison of the observed
colour-magnitude diagram with synthetic counterparts that account for the
galaxy distance modulus, reddening and photometric errors, suggests the
presence of an old (~13Gyr) and metal poor ([Fe/H]~-1.3) population. This
object is most likely a relatively isolated satellite dwarf spheroidal galaxy
of the nearby great spiral NGC 6744, or potentially the most distant isolated
dwarf spheroidal known with a secure distance.
