Observations of transits of the TrES-2 exoplanet

With a period of 2.470621 days, the TrES-2 exoplanet exhibits almost "grazing" transits 110.4-minutes duration as measured in 2006 by Holman and collaborators (2007, Cat. <J/ApJ/664/1185>). We observed two transits of TrES-2 in 2008 using the 1.2m Oskar-Luhning telescope (OLT) of Hamburg observatory employing CCD photometry in an i-band and a near to R-band filter.

A careful lightcurve analysis including a re-analys is of the 2006 observations shows that the current transit duration has shortened since 2006 by ~3.16-minutes. Although the new observations were taken in a different filter we argue that the observed change in transit duration time cannot be attributed to the treatment of limb darkening. If we assume the stellar and planetary radii to be constant, a change in orbit inclination is the most likely cause of this change in transit duration.