TASTE. II. A new observational study of transit time variations in   HAT-P-13b
  TASTE (The Asiago Search for Transit timing variations of Exoplanets) project is collecting high-precision, short-cadence light curves for a selected sample of transiting exoplanets. It has been claimed that the hot jupiter HAT-P-13b suddenly deviated from a linear ephemeris by $\sim 20$ min, implying that there is a perturber in the system. Using five new transits, we discuss the plausibility of this transit time variation (TTV), and show that a periodic signal should not be excluded. More follow-up observations are required to constrain the mass and the orbit of the hypothetical perturber. 
V. Nascimbeni, G. Piotto, L. R. Bedin, M. Damasso, L. Malavolta, and   L. Borsato
astro-ph.EP astro-ph.IM