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KOI's (Blue)  or
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     Kepler KOI-4087 (Kepler-440b, KIC-6106282) 2-(or more?)-Planet System

TTV Evidence:
There appears to be a pronounced TTV in the case of KOI-4087.01 (see plot) but the values for P_ttv and Amp_ttv are not well constrained (and are very different for the two analytical approaches (Lomb-Scargle Periodogram and sinusoidal curve-fit).  This is very likely due to the considerably-less-than-one-cycle that was observed during the entire Q1-Q17 time frame.

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-4087.01, P = 101.11 days [Plot avg. error bars = ± 8.50 min.]
Sinusoidal Best-fit Curve:
TTV_minimum: ~ 776 days, Amp_ttv_minimum: ~ -35 min.
P_ttv: ~ 6069 days.
Amp_ttv: ~ 689 minutes.
Lomb-Scargle periodogram, periodicity (P_ttv): 1643.34 days; Power: 2.88; FAP: 0.106.
Linear ephemeris (this work): Tc = [101.11326625 ± 0.00193313](Tc#) + [148.50097513 ± 0.01448060]

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

4 Dec 2014