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 3.: KOI-1598.03, P = 13.93 days [Plot avg. error bars = ± 10.68 min.] Linear ephemeris (this work): Tc = [13.93068744 ± 0.00011092](Tc#) + [67.42933216 ± 0.00698975]
Numerous literature and major Tc#, Tc, and TTV tabulation references can be found on my "Summary" webpage following the table.
1 Jun 2015
Kepler KOI-1598 (Kepler-310, KIC-10004738) 4-(or more?)-Planet System
Discussion: A sinusoidal curve-fit of the [(O-C) vs. Time] data for KOI-1598.01 Kepler-310c) showed (Figure 1.) a periodicity (P_ttv) of 318.47 ± 8.64 days; a Lomb-Scargle Periodogram (LSP) of the same data gave a medium-credibility periodicity of 319.94 days. Potentially, a non-transiting planet is gravitationally interacting with KOI-1598.01 in this system.
A sinusoidal curve-fit of the [(O-C) vs. Time] data for KOI-1598.02 (Kepler-310d) showed (Figure 2.) a periodicity (P_ttv) of 416.84 ± 16.23 days; a Lomb-Scargle Periodogram (LSP) of the same data gave a medium-credibility periodicity of 418.32 days. Potentially, a non-transiting planet is gravitationally interacting with KOI-1598.02 in this system.
The innermost known planet, KOI-1598.03 (Kepler-310b), showed no TTV (see Figure 3.).
For 1598.01 and 1598.02, the differences in the their P_ttv values, the lack of anti-correlation of their sinusoidal curves, and their the non-[ j ÷ (j-1) ] period ratio all suggest that they are not responsible for each others observed TTVs. Thus, there could be (1) a 4th non-transiting planet between them, interacting with both, or (2) a 4th and 5th non-transiting planet each interacting separately.