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-757.03, P = 6.25 days [Plot avg. error bars = ± 8.05 min.]
Linear ephemeris (this work): Tc = 6.25297244(Tc#) + 104.29892733
Figure: KOI-757.01, P = 16.07 days [Plot avg. error bars = ± 2.63 min.]
Linear ephemeris (this work): Tc = 16.06863959(Tc#) + 106.62278788
Figure: KOI-757.02, P = 41.19 days [Plot avg. error bars = ± 5.51 min.]
TTV_minimum: ~ 766 days, Amp_ttv_minimum: ~ -28 min.
Linear ephemeris (this work): Tc = 41.19688454(Tc#) + 98.00936743
For literature references, including Tc#, Tc, and major TTV tabulations, see my "Summary" webpage.
25 July 2014
KOI-757 (Kepler-229, KIC-10910878) System
When less than one cycle of periodicity has been observed by Kepler, the P_ttv values derived from a best-fit sinusoidal curve and the corresponding Lomb-Scargle periodogram can be quite different…and even sometimes (from the former method) not very precise. This is the case for KOI-757.02 (see plot and data below). Clearly, this can only be remedied by longer-term observations…which may or may not be in the offing.