Photometry of Kepler-9b and c transits

These TTVs results from the dynamical interaction amplified by the near 2:1 period resonance of the planets. The dynamical cycle was only almost finished when the Kepler telescope stopped the observations on that field.

To complement the dynamical cycle of this and other Kepler Objects of Interest (KOIs) showing TTVs, the KOINet was build to organize follow-up observations with ground-based telescopes. These follow-up observations of Kepler-9b/c transits were used in a detailed photodynamical modelling of the system and increased the accuracy of the derivable system parameters.