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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.

Discussion:
The two confirmed Kepler exoplanets, Kepler-49b and -49c (KOI-248.01 and-248.02, respectively) clearly show strongly anti-correlated TTV behavior through their best-fit sinusoidal curves, one more signature dance of two planets with periods in near mean motion resonance of 2:3 (actually, 2.00:3.03).  The observed P_ttv's for Q1-16 are very similar to those reported by Xie(2012) and Mazeh(2013) (values and references below) for the Q1-9 and Q1-12 time frames, respectively.  That the "P_ttv-V" effect is unimportant in these comparisons is expected since there were already more than two full sinusoidal cycles observed by Q9.

1st: KOI-248.03, P = 2.58 days [Plot error bars = ± 7.07 min.]
No sinusoidal TTV was observed for this relatively close-in planetary candidate.
Linear ephemeris (this work): Tc = 2.57656683(Tc#) + 105.12840294

2nd: KOI-248.01, P = 7.20 days [Plot error bars = ± 4.51 min.]
TTV_maximum: 104.21 ± 14.62 days, Amp_ttv_maximum: 8.60 ± 1.27 min.
TTV_minimum: 287.71 ± 15.26 days, Amp_ttv_minimum: -9.78 ± 1.27 min.
TTV_maximum: 471.20 ± 16.43 days, Amp_ttv_maximum: 8.60 ± 1.27 min.
TTV_minimum: 654.69 ± 18.03 days, Amp_ttv_minimum: -9.78 ± 1.27 min.
TTV_maximum: 838.18 ± 19.95 days, Amp_ttv_maximum: 8.60 ± 1.27 min.
TTV_minimum: 1021.67 ± 22.12 days, Amp_ttv_minimum: -9.78 ± 1.27 min.
TTV_maximum: 1205.16 ± 24.46 days, Amp_ttv_maximum: 8.60 ± 1.27 min.
TTV_minimum: 1388.66 ± 26.93 days, Amp_ttv_minimum: -9.78 ± 1.27 min.
P_ttv: 366.98 ± 5.99 days.
Amp_ttv: 18.38 ± 1.80 minutes.
Lomb-Scargle periodogram, candidate P_ttv: 367.90 days; Power: 26.31; P-value: 5.894 x 10^-9.
Linear ephemeris (this work): Tc = 7.20384330(Tc#) + 103.28899763
Estimated P_ttv = 1/|(nmmri_a/P_a - nmmri_b/P_b)| = 367.33 days


3rd: KOI-248.02, P = 10.91 days [Plot error bars = ± 4.84 min.]
TTV_minimum: 90.98 ± 13.28 days, Amp_ttv_minimum: -18.76 ± 2.23 min.
TTV_maximum: 272.60 ± 13.78 days, Amp_ttv_maximum: 19.39 ± 2.23 min.
TTV_minimum: 454.23 ± 14.73 days, Amp_ttv_minimum: -18.76 ± 2.23 min.
TTV_maximum: 635.85 ± 16.04 days, Amp_ttv_maximum: 19.39 ± 2.23 min.
TTV_minimum: 817.48 ± 17.65 days, Amp_ttv_minimum: -18.76 ± 2.23 min.
TTV_maximum: 999.11 ± 19.47 days, Amp_ttv_maximum: 19.39 ± 2.23 min.
TTV_minimum: 1180.73 ± 21.45 days, Amp_ttv_minimum: -18.76 ± 2.23 min.
TTV_maximum: 1362.36 ± 23.55 days, Amp_ttv_maximum: 19.39 ± 2.23 min.
P_ttv: 363.25 ± 5.20 days.
Amp_ttv: 38.15 ± 3.15 minutes.
Lomb-Scargle periodogram, candidate P_ttv: 364.18 days; Power: 26.93; P-value: 2.026 x 10^-9.
Linear ephemeris (this work): Tc = 10.91277215(Tc#) + 102.85163563


Reference:
• Ford2012arXiv-1201.1892; TTV data thru Q6 of KOI-248.01 & KOI-248.02.
• P_ttv equation: P_ttv = 1/|(nmmri_a/P_a - nmmri_b/P_b)|…(see Fabrycky, et al., 2012, arXiv-1201.5415)
• Xie2013arXiv-1208.3312v1; TTV data thru Q9: KOI-248.01 & KOI-248.02: 367.7 days.
• Mazeh2013arXiv-1301.5499v1; TTV data thru Q12: KOI-248.01: 368 ± 43 days; KOI-248.02: 354 ± 47 days.

21 Oct 2013; updated: 19 May 2015
KOI-248 (Kepler-49, KIC-5364071) 4-(or more?)-Planets