TTVs are derived from Q1-Q15 Kepler data. x-axes: “Observed Tc” (Mid-Transit Time): EXOFAST’s best-fits from Kepler light flux vs. time data. y-axes: “(O – C)”: difference between Observed Tc and the Calculated Tc from the graphically obtained linear ephemeris. The plots are pictured in the order of orbital periods (smallest first).
Data from Q1-Q15 clearly shows a TTV anti-correlation between KOI-1831.03 and KOI-1831.01 (and their periods are near mean motion resonance of 3:2; observed: 3.03:2); the respective TTV_maximum and TTV_minimum are only slightly displaced by 14.66 days (753.24 vs. 767.80 days) and occur during Q9. The P_ttv values and Lomb-Scargle periodogram main peak values do not agree well probably because the sinusoidal "best-fit" curves are each based on only ~ half of a frequency cycle.
1st: KOI-1831.02, P = 4.39 days [Plot error bars (smaller than symbol) = ± 8.63 min.]
No distinctive TTV (see plot).
Linear ephemeris: Tc = 4.38535441(Tc#) + 72.22429436
NO IMAGE: KOI-1831.04, P = 13.98 days
Too weak for good fits of individual transits; NEA-reported duration from folded transits = 1.398 hr., i.e., only 2-3 LC data points per transit; depth = 297 ppm.
2nd: KOI-1831.03, P = 34.21 days [Plot error bars (smaller than symbol) = ± 7.66 min.]
TTV_maximum: 753.24 ± 191.72 days, Amp_ttv_maximum: 161.25 ± 67.89 min.
The correlation coefficient, 0.9603, of the sinusoidal curve adds credibility to the follow values: