  We use Hubble Space Telescope (HST) to reach the end of the white dwarf (WD)
cooling sequence (CS) in the solar-metallicity open cluster NGC 6819. Our
photometry and completeness tests show a sharp drop in the number of WDs along
the CS at magnitudes fainter than mF606W = 26.050+/- 0.075. This implies an age
of 2.25+/-0.20 Gyr, consistent with the age of 2.25+/-0.30 Gyr obtained from
fits to the main-sequence turn-off. The use of different WD cooling models and
initial-final-mass relations have a minor impact the WD age estimate, at the
level of ~0.1 Gyr. As an important by-product of this investigation we also
release, in electronic format, both the catalogue of all the detected sources
and the atlases of the region (in two filters). Indeed, this patch of sky
studied by HST (of size ~70 arcmin sq.) is entirely within the main
Kepler-mission field, so the high-resolution images and deep catalogues will be
particularly useful.
