TTVs are derived from Q1-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.
Numerous literature and major Tc#, Tc, and TTV tabulation references can be found on my "Summary" webpage following the table.
19 May 2015
Kepler KOI-2092 (Kepler-359; KIC-6696580) 4-(or more?)-Planet System
Discussion: In the example of KOI-2092.02 (Kepler-359b), a sinusoidal curve-fit of the (O-C) vs. Time data showed (Figure. below) a periodicity (P_ttv) of 1059.29 ± 215.73 days; 1129.76 days was the main periodicity observed in the Lomb-Scargle Periodogram (LSP) of the same data. While it is possible (see recent work of Lithwick and others) that some of this curvature obtains from eccentric orbits (and maybe even precessing eccentric orbits) of planetary objects in this system, it is also possible that one more planet over the known three, that is just enough outside the system’s main orbital plane to not transit, is interacting with 2092.02 to give the observed TTV.