Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high eccentricity migration. However, few such exoplanets transit their host stars thus removing the ability to apply constraints on formation from their bulk internal compositions. We report the discovery of Kepler-1704 b, a transiting 4.15 $M_{\rm J}$ giant planet on a 988.88 day orbit with the extreme eccentricity of $0.921^{+0.010}_{-0.015}$. Our decade-long RV baseline from the Keck I telescope allows us to measure the orbit and bulk heavy element composition of Kepler-1704 b and place limits on the existence of undiscovered companions. Kepler-1704 b is a failed hot Jupiter that was likely excited to high eccentricity by scattering events that possibly began during its gas accretion phase. Its final periastron distance was too large to allow for tidal circularization, so now it orbits it host from distances spanning 0.16 - 3.9 au. The maximum difference in planetary equilibrium temperature resulting from this elongated orbit is over 700 K. A simulation of the thermal phase curve of Kepler-1704 b during periastron passage demonstrates that it is a remarkable target for atmospheric characterization from the James Webb Space Telescope, which could potentially also measure the planet's rotational period as the hot spot from periastron rotates in and out of view. Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system.

In the original analysis by Dalba et al. (2021) to confirm and characterize the Kepler-1704 system, an erroneous offset of 0.53878357713256 day was accidentally subtracted from the time stamps of the photometric measurements of this star acquired by the Kepler spacecraft. This photometry was then used in the comprehensive system modeling that yielded the final ephemeris of this exoplanet. As a result, parameters describing the timing of this planet’s orbit, most notably its conjunction (transit) time, were erroneously offset. This erratum serves to correct this error and the ephemeris of Kepler-1704 b. We added the 0.53878357713256 day offset to the time stamps of the Kepler photometry that was used in the original analysis. The corresponding flux values were unchanged. Besides the time stamps, we did not alter any other data product. We then conducted the joint modeling of the stellar and planetary parameters of the Kepler-1704 system using EXOFASTv2 (Eastman et al. 2019) exactly as described in Section 3 of Dalba et al. (2021). All priors and EXOFASTv2 settings were left as described in the original analysis. This new fit converged following the same criteria applied in the original analysis. We again observed a bimodality in mass and age of Kepler-1704 as described in Section 3.1 of Dalba et al. (2021). We selected the lower stellar mass solution just as before and calculated the updated stellar and planetary parameters, which are listed in Tables 1 and 2, respectively. The only parameter values in Tables 1 and 2 that changed significantly between Dalba et al. (2021) and this analysis are conjunction time (TC), periastron time (TP), and eclipse time (TS). This is expected given that the only change to the inputs to the EXOFASTv2 fit were the time stamps of the Kepler photometry. Changes for other parameters other than those listed above were only due to rounding error or small statistical variations in the Markov chain Monte Carlo analysis, and were all well within the 1σ uncertainties. Figure 1 shows the Kepler light curves with the updated time stamps and the updated best-fit models. This figure is analogous to Figure 5 of Dalba et al. (2021). Table 3 shows the updated predictions for the timing of future transits and periastron passages. Asexpected, the time of these events are shifted forward by the value of the time stamp offset relative to the corresponding times published in Table 4 of Dalba et al. (2021). We conducted two consistency checks of the new ephemeris for Kepler-1704 b. First, we accessed the Kepler Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP; Jenkins et al. 2010; Smith et al. 2012; Stumpe et al. 2012) photometry of Kepler-1704 from Quarters 2 and 13 via the Mikulski Archive for Space Telescopes but we did not conduct any additional detrending. We inserted the unaltered PDCSAP transit light curves into the exact same EXOFASTv2 fit, which proceeded until convergence. The resulting orbital elements are consistent this with those listed in Table 2. Second, we accessed the Transit and Ephemeris Service on the NASA Exoplanet Archive15 and predicted future transit times of Kepler-1704 b using the planet candidate solution from the Kepler Quarter 1–17 Data Release 25 Supplemental Kepler Object of Interest Table. The resulting transit times forthe four events spanning the years 2023–2031 agreed with the transit times listed in Table 3 to within 1 minute.

Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high-eccentricity migration. However, few such exoplanets transit their host stars, thus removing the ability to apply constraints on formation from their bulk internal compositions. We report the discovery of Kepler-1704 b, a transiting 4.15 M J giant planet on a 988.88 day orbit with an extreme eccentricity of 0.921-0.015+0.010. Our decade-long RV baseline from the Keck I telescope allows us to measure the orbit and bulk heavy-element composition of Kepler-1704 b and place limits on the existence of undiscovered companions. A failed hot Jupiter, Kepler-1704 b was likely excited to high eccentricity by scattering events that possibly began during its gas accretion phase. Its final periastron distance was too large to allow for tidal circularization, so now it orbits its host from distances spanning 0.16-3.9 au. The maximum difference in planetary equilibrium temperature resulting from this elongated orbit is over 700 K. A simulation of the thermal phase curve of Kepler-1704 b during periastron passage demonstrates that it is a remarkable target for atmospheric characterization from the James Webb Space Telescope, which could potentially also measure the planet's rotational period as the hot spot from periastron rotates in and out of view. Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system.

Exoplanet discoveries have revealed a dramatic diversity of planet sizes across a vast array of orbital architectures. Sub-Neptunes are of particular interest; due to their absence in our own solar system, we rely on demographics of exoplanets to better understand their bulk composition and formation scenarios. Here, we present the discovery and characterization of TOI-1437 b, a sub-Neptune with a 18.84 day orbit around a near-solar analog (M⋆ = 1.10 ± 0.10 M☉, R⋆=1.17 ± 0.12 R☉). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite (TESS) mission and radial velocity (RV) follow-up observations were carried out as a part of the TESS-Keck Survey using both the HIRES instrument at Keck Observatory and the Levy Spectrograph on the Automated Planet Finder telescope. A combined analysis of these data reveal a planet radius of Rp = 2.24 ± 0.23 R⊕ and a mass measurement of Mp = 9.6 ± 3.9 M⊕). TOI-1437 b is one of few (∼50) known transiting sub-Neptunes orbiting a solar-mass star that has a RV mass measurement. As the formation pathway of these worlds remains an unanswered question, the precise mass characterization of TOI-1437 b may provide further insight into this class of planet.

With JWST’s successful deployment and unexpectedly high fuel reserves, measuring the masses of sub-Neptunes transiting bright, nearby stars will soon become the bottleneck for characterizing the atmospheres of small exoplanets via transmission spectroscopy. Using a carefully curated target list and observations from more than 2 yr of APF-Levy and Keck-HIRES Doppler monitoring, the TESS-Keck Survey is working toward alleviating this pressure. Here we present mass measurements for 11 transiting planets in eight systems that are particularly suited to atmospheric follow-up with JWST. We also report the discovery and confirmation of a temperate super-Jovian-mass planet on a moderately eccentric orbit. The sample of eight host stars, which includes one subgiant, spans early-K to late-F spectral types (T eff = 5200-6200 K). We homogeneously derive planet parameters using a joint photometry and radial velocity modeling framework, discuss the planets’ possible bulk compositions, and comment on their prospects for atmospheric characterization.

We report the discovery of TOI-561, a multiplanet system in the galactic thick disk that contains a rocky, ultrashort- period planet. This bright (V = 10.2) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561 b (TOI-561.02, P = 0.44 days, Rp = 1.45 ± 0.11 R⊕), c (TOI-561.01, P = 10.8 days, Rp = 2.90 ± 0.13 R⊕), and d (TOI-561.03, P = 16.3 days, Rp = 2.32 ± 0.16 R⊕). The star is chemically ([Fe/ H] = -0.41 ± 0.05, [a/Fe]=+0.23 ± 0.05) and kinematically consistent with the galactic thick-disk population, making TOI-561 one of the oldest (10 ± 3 Gyr) and most metal-poor planetary systems discovered yet. We dynamically confirm planets b and c with radial velocities from the W. M. Keck Observatory High Resolution Echelle Spectrometer. Planet b has a mass and density of 3.2 ± 0.8M⊕ and 5.5+2.0-1.6g cm-3, consistent with a rocky composition. Its lower-than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out. Planet c is 7.0 ± 2.3M⊕ and 1.6 ± 0.6 g cm-3, consistent with an interior rocky core overlaid with a low-mass volatile envelope. Several attributes of the photometry for planet d (which we did not detect dynamically) complicate the analysis, but we vet the planet with high-contrast imaging, groundbased photometric follow-up, and radial velocities. TOI-561 b is the first rocky world around a galactic thick-disk star confirmed with radial velocities and one of the best rocky planets for thermal emission studies.