TTVs are derived from Q1-Q16 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.
Thanks to a recent publication by Ofir, Dreizler et al. (vide infra), the true period of the outermost known planet in this system, KOI-1574.02, has been revealed as ~ 191.23 days. Due to data gaps and the ultimate duration of the 3-gyroscope-stable-Kepler observations, only 4 transits of this planet were recorded. Through Q16, as seen in the above plots, the TTVs of 1574.01 and 1574.02 are either: (a) reasonably well anti-correlated with the small offset seen arising from errors implicit in a 4-point sinusoidal fit, or (b) actually offset because of gravitational effect of other planetary object(s), orbital eccentricities, and/or orbital precessions. [Potentially, the ground-based "KAFO" project (ref. below) may characterize more transits of either or both 1574.01 and 1574.02 to help illuminate this system's behavior and/or to refine the P_ttv and Amp_ttv's reported below.] No TTV pattern was noted for KOI-1574.03 or KOI-1574.04, the closest-in planets.
1st Plot: KOI-1574.03, P = 5.83 days [Plot error bars = ± 9.87 min.]
Linear ephemeris (this work): Tc = 5.83351163(Tc#) + 65.65386889
2nd Plot: KOI-1574.04, P = 8.98 days [Plot error bars = ± 10.64 min.]
Linear ephemeris (this work): Tc = 8.97735485(Tc#) + 452.47869332
3rd Plot: KOI-1574.01, P = 114.74 days [Plot error bars = ± 1.92 min.]
TTV_minimum: 374.84 ± 45.71 days, Amp_ttv_minimum: -10.59 ± 2.52 min.
TTV_maximum: 649.54 ± 54.80 days, Amp_ttv_maximum: 11.08 ± 2.52 min.
TTV_minimum: 924.25 ± 66.38 days, Amp_ttv_minimum: -10.59 ± 2.52 min.
TTV_maximum: 1198.96 ± 79.36 days, Amp_ttv_maximum: 11.08 ± 2.52 min.