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.
Figure 4.: Summed combination of Figures 1., 2., and 3. [Plot error bars = ± 4.22 min.]
Numerous literature and major Tc#, Tc, and TTV tabulation references can be found on my "Summary" webpage following the table.
1 Feb 2015
Kepler KOI-92.01 (KIC-7941200) 4-(or more?)-Planet System
Discussion: After a sinusoidal curve-fit of the (O-C) vs. Time data showed (Figure 1.) a periodicity (P_ttv) of 432.48 ± 23.61 days (436.46 days was observed in the Lomb-Scargle Periodogram (LSP) of the same data), a plot (Figure 2.) of the Residuals also gave a good sinusoidal curve-fit with a periodicity of 651.16 ± 38.24 days (LSP: 655.23 days). Similarly, a plot (Figure 3.) of the Residuals of the Residuals gave a good sinusoidal curve-fit with a periodicity of 189.97 ± 4.39 days (LSP: 189.45 days). The added combination of these three sinusoidal curves is arrayed in Figure 4. and reasonably reproduces a complex overall curvature consistent with the initial data. While the sinusoidal behaviors observed could be partially due to orbital eccentricities, it is also possible that 3 additional as yet unseen (non-transiting) planets are present in the system.