The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30% to nearly 100%, with the mass of the outermost, P = 18.8 d, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding e < 0.02 for inner six known members of the system), and we derive masses of 0.79 ± 0.27 M ⊕ , 1.63 ± 0.63 M ⊕ , 0.33 ± 0.15 M ⊕ , 0.24 +0.56 −0.24 M ⊕ , 0.36 ± 0.12 M ⊕ , 0.566 ± 0.038 M ⊕ , and 0.086 ± 0.084 M ⊕ for planets b, c, d, e, f, g, and h, respectively.

The Kepler-9 system harbors three known transiting planets. The system holds significant interest for several reasons. First, the outer two planets exhibit a period ratio that is close to a 2:1 orbital commensurability, with attendant dynamical consequences. Second, both planets lie in the planetary mass "desert" that is generally associated with the rapid gas agglomeration phase of the core accretion process. Third, there exist attractive prospects for accurately measuring both the sky-projected stellar spin-orbit angles as well as the mutual orbital inclination between the planets in the system. Following the original Kepler detection announcement in 2010, the initially reported orbital ephemerides for Kepler-9 b and c have degraded significantly, due to the limited time base-line of observations on which the discovery of the system rested. Here, we report new ground-based photometric observations and extensive dynamical modeling of the system. These efforts allow us to photometrically recover the transit of Kepler-9 b, and thereby greatly improve the predictions for upcoming transit midtimes. Accurate ephemerides of this system are important in order to confidently schedule follow-up observations of this system, for both in-transit Doppler measurements as well as for atmospheric transmission spectra taken during transit.

We present eight new light curves of the transiting extra-solar planet HAT-P-25b obtained from 2013 to 2016 with three telescopes at two observatories. We use the new light curves, along with recent literature material, to estimate the physical and orbital parameters of the transiting planet. Specifically, we determine the mid-transit times (T C ) and update the linear ephemeris, T C[0] =2456418.80996±0.00025 [BJD TDB ] and P=3.65281572±0.00000095 days. We carry out a search for transit timing variations (TTVs), and find no significant TTV signal at the ΔT=80 s-level, placing a limit on the possible strength of planet-planet interactions (TTV G ). In the course of our analysis, we calculate the upper mass-limits of the potential nearby perturbers. Near the 1:2, 2:1, and 3:1 resonances with HAT-P-25b, perturbers with masses greater than 0.5, 0.3, and 0.5 M ⊕ respectively, can be excluded. Furthermore, based on the analysis of TTVs caused by light travel time effect (LTTE) we also eliminate the possibility that a long-period perturber exists with M p >3000 M J within a=11.2 au of the parent star.

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We report the photometry of six transits of the hot Jupiter HAT-P-29b obtained from 2013 October to 2015 January. We analyze the new light curves, in combination with the published photometric, and Doppler velocimetric, and spectroscopic measurements, finding an updated orbital ephemeris for the HAT-P-29 system, T C [0] = 2456170.5494(15) [BJD TDB ] and P = 5.723390(13) days. It is 17.63 s (4.0 σ) longer than the previously published value, amounting to errors exceeding 2.5 hrs at the time of writing (on UTC 2018 June 1). The measured transit mid-times for HAT-P-29b show no compelling evidence of timing anomalies from a linear model, which rules out the presence of a perturbers with masses greater than 0.6, 0.7, 0.5, and 0.4 M ⊕ near the 1 : 2, 2 : 3, 3 : 2, and 2 : 1 resonances with HAT-P-29b, respectively.