Even though there was considerable errors and error bars in the above plot, the credibility of the indicated TTV is strongly suggested by the Lomb-Scargle periodogram (LSP) data (especially with an False-Alarm Probability (FAP) of zero) and the close correspondence of the periodicity of the best-fitting sinusoidal curve to that in the LSP.
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.
*Szabó et al. reported no such P_ttv for this system using Ford's data for Kepler Q1-5. Since we were able to use data for Kepler Q1-5, 7-9, 11-13, & 15-17, this is again is another good example of what is discussed on webpage "P_ttvV".
References: • R. Szabó, Gy. M. Szabó, G. Dálya, A. E. Simon, G. Hodosán, and L. L. Kiss, A & A, 553, A17, May, 2013; arXiv:1207.7229. • Ford's website: http://www.astro.ufl.edu/~eford/data/kepler/TT_Q0-6/tab_transit_times_electronic.txt • Numerous additional pertinent literature and major Tc#, Tc, and TTV tabulations can be found on my "Summary" webpage following the table.
6 Feb 2015
Kepler KOI-823 (KIC-5115978) 2-(or more?)-Planet System