Exoplanets, or extrasolar planets, are bodies orbiting around stars different from the sun. The first discovery of an exoplanet was done by the swiss astronomers Michel Mayor and Didier Queloz.
In 2002 I tried to monitor the magnitude drop of this star under non ideal sky conditions. The lightcurve is here but the precision of the measurements is poor.
In 2006 I tried again. This time the lightcurve looks better.
The planet circling this 8mag star was found by a group of french astronomers. Their web site clears the details of the discovery.
In the evening of Oct_25_2005 it was predicted a transit of the b-planet. Initially the night was cloudy but afterwards the sky cleared. In 4 hours observing I captured a 0,03mag drop of the brightness of the star. This drop lasted 1h and 40m.
The star HD189733 is just East from the Dumbell nebula (North=up; East=left).
In September 2007 I could record from Gnosca the 0.02mag drop of the exoplanet b of the star TrES-1.
I shot 176 60s-CCD images for a sum of 3.3hours. The whole lightdrop lasted 2.5hours.