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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-4007.01, P = 11.49 days [Plot avg. error bars = ± 11.05 min. (smaller than symbols)]
TTV_minimum: 101.31 ± 75.42 days, Amp_ttv_minimum: -62.01 ± 13.32 min.
TTV_maximum: 664.01 ± 96.38 days, Amp_ttv_maximum: 70.51 ± 13.32 min.
TTV_minimum: 1226.70 ± 134.85 days, Amp_ttv_minimum: -62.01 ± 13.32 min.
P_ttv: 1125.39 ± 102.91 days.
Amp_ttv: 132.51 ± 18.84 minutes.
Lomb-Scargle periodogram, periodicity (P_ttv): 1154.20 days; Power: 14.75; FAP: 0.000399.
Linear ephemeris (this work): Tc = 11.49364865(Tc#) + 66.28829168


Related TTV Tabulations and References:
• For Q0-6 TTV data (thru ~ 563 (BJD-2454900) days): Ford et al., 2012, arXiv-1201.1892.
• For Q0-10 TTV data (thru ~ 934 (BJD-2454900) days): Rowe et al., 2014, arXiv-1402.6534.
• For Q0-12 TTV data (thru ~ 1116 (BJD-2454900) days): Mazeh et al., 2013, arXiv-1301.5499.
• For Q0-12 Calc. properties from TTVs: Hadden & Lithwick, 2013, arXiv-1310.7942.
• For Q0-13/14 TTV data, Xie: http://www.astro.utoronto.ca/~jwxie/TTV/TTV_Home.html
• Two ground-based Kepler-TTV-follow-up programs are in place at the moment:
 --- Gary, "KAFO" project: http://brucegary.net/kafo/
 --- von Essen, "KOINet": http://koinet.astro.physik.uni-goettingen.de/

28 Apr 2014
              Kepler KOI-4007.01 (KIC-8376848) 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 closely 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.