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KOI's (Blue)  or
K2 Objects (Green)

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.

Figure: KOI-902.01, P = 83.93 days [Plot avg. error bars = ± 2.06 min. (smaller than symbols)]
TTV_minimum: 798.64 ± 322.41 days, Amp_ttv_minimum: -64.30 ± 211.93 min.
P_ttv: 3974.43 ± 1134.29 days.
Amp_ttv: 582.60 ± 299.71 minutes.
Lomb-Scargle periodogram, candidate P_ttv: 1625.73 days; Power: 8.05; FAP: 2.559 x 10^-9.
Linear ephemeris (this work): Tc = [83.92845279 ± 0.00186240](Tc#) + [169.75908288 ± 0.01698434]

Numerous literature and major Tc#, Tc, and TTV tabulation references can be found on my "Summary" webpage following the table.

25 May 2015
                       Kepler KOI-902 (KIC-8018547) 2-(or more?)-Planet System

TTV Evidence:
For KOI-902.01, the presence of both a highly credible periodicity in the Lomb-Scargle Periodogram (LSP) of [(O-C) vs. Time] ("TTVxy") data points [1625.73 days] along with a sinusoidal curve-fit of the same points displaying a strong periodicity, "P_ttv”[3974.43 ± 1134.29 days] (see Figure below), is strongly suggestive of the presence of an unseen (non-transiting), gravitationally perturbing planetary object in this system.  While periodicity values from both methods are large and visually obvious, the periodicities do not correspond very closely to one another because considerably less than one cycle of periodicity was observed which significantly affects the choice of "best-fit" sinusoidal curve.  (See also the webpage entitled “P_ttvV”.)