Kepler KOI-3678 (KIC-4150804) 2-(or more?)-Planet System
TTV Evidence: The presence of both a credible periodicity in the Lomb-Scargle Periodogram (LSP) and a corresponding pronounced one (P_ttv) in a sinusoidal distribution of [(O-C) vs. Time] ("TTVxy") data points is strongly suggestive of the presence of a second (possibly unseen, non-transiting) gravitationally-perturbing planetary object in a system. This is the case for KOI-3678.01.
TTVs are derived from Q0-Q17 Kepler data. x-axes: “Observed Tc” (Mid-Transit Time): EXOFAST’s best-fits from Normalized PDCSAP_FLUX Kepler light flux vs. time (BJD_tdb - 2454900) data. y-axes: “(O-C)”: difference between Observed Tc and the Calculated Tc from the graphically obtained linear ephemeris.