Description
We monitored three transits of the giant gas planet around the nearby K dwarf HD 189733 with the ACS camera on the Hubble Space Telescope. The resulting very-high accuracy light-curve (signal-to-noise ratio near 15000 on individual measurements, 35000 on 10-min averages) allows a direct geometric measurement of the orbital inclination, radius ratio and scale of the system: i=85.68+/-0.04, Rpl/R*=0.1572+/-0.0004, a/R*=8.92+/-0.09.
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