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KOI's (Blue)  or
K2 Objects (Green)

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: KOI-1271.01, P = 162.02 days [Plot avg. error bars = ± 1.12 min. (smaller than symbols)]
TTV_minimum: 735.62 ± 184.02 days, Amp_ttv_minimum: -268.07 ± 97.94 min.
TTV_maximum: 1388.82 ± 264.33 days, Amp_ttv_maximum: 282.05 ± 97.94 min.
P_ttv: 1306.39 ± 210.43 days.
Amp_ttv: 550.12 ± 138.50 minutes.
Lomb-Scargle periodogram, candidate P_ttv: 1309.41 days; Power: 2.68; FAP: 0.1011.
Linear ephemeris (this work): Tc = 162.01604367(Tc#) + 212.04074033

Related TTV Tabulations and References:
• For Q0-6 TTV data (thru ~ 563 (BJD-2454900) days), see: Ford et al., 2012, arXiv-1201.1892.
• For Q0-10 TTV data (thru ~ 934 (BJD-2454900) days), see Rowe et al., 2014, arXiv-1402.6534.
• For Q0-12 TTV data (thru ~ 1116 (BJD-2454900) days), see: Mazeh et al., 2013, arXiv-1301.5499.
• For Q0-12 Calc. properties from TTVs, see: Hadden & Lithwick, 2013, arXiv-1310.7942.
• For Q0-14 TTV data, see Ji-Wei Xie's website:
• Two ground-based Kepler-TTV-follow-up programs are in place at the moment: --- see: B Gary, "KAFO" project, see: --- see: vonEssen et al., "KOINet", see:

27 Apr 2014
Kepler KOI-1271.01 (KIC-8631160) 2-(or more?)-Planet System

TTV Evidence:
The presence of both a credible (i.e.: False Alarm Probability (FAP) < 0.1) periodicity in the Lomb-Scargle Periodogram (LSP) of [(O-C) vs. Time] ("TTVxy") data points, along with a sinusoidal distribution of the same points displaying a corresponding periodicity ("P_ttv") (see Figure(s) below), is strongly suggestive of the presence of an unseen (non-transiting), gravitationally perturbing planetary object(s) in this system.