TOI-1232 is a G dwarf star with a mass of 1.06(-0.06)(+0.07)M(circle dot) , a radius of 1.07 +/- 0.05 R-circle dot, and a slightly higher metallicity than solar of Fe/H = 0.18 +/- 0.05. The star hosts a transiting warm Jovian-mass planet, TOI-1232 b, with an orbital period of P-b=14.256(-0.001)(+0.001 )days, identified with data from multiple sectors of the TESS space telescope. The TESS light curve of TOI-1232 is complex, as it is contaminated by a background eclipsing binary with a period of 1.37 days. TOI-1232 b was firmly confirmed by ground-based transit follow-up campaigns from the Las Cumbres, Hazelwood, Brierfield, and ASTEP observatories. Additionally, the TESS transits of TOI-1232 b exhibit strong transit-timing variations (TTVs) with a superperiod of 235.5 +/- 0.7 days and a semiamplitude of 27 minutes. Radial velocity (RV) follow-up with the FEROS spectrograph confirms the planetary nature of the transiting candidate, while a self-consistent N-body analysis of RVs and TTVs pinpoints the presence of a second outer Saturn-mass companion, TOI-1232 c with a period of P-c=30.356(-0.012)(+0.010) days. The TOI-1232 warm-giant system is particularly important due to the evidence of two massive planets that reside near the 2:1 commensurability but are not locked in a mean-motion resonance. Thanks to TESS, we have revealed a handful of these rare systems. Hence, TOI-1232 is an important addition to understanding the formation and dynamical evolution of such compact, massive, warm giant planets.

Giant planets orbiting low-mass M dwarfs challenge current planet formation theories, which predict that such planets are unlikely to form. Characterizing their atmospheres can provide key insight into their origins, but analysis is complicated by stellar contamination in transmission spectra. We present a JWST/NIRSpec PRISM transmission spectrum of TOI-3235 b, a 604 K, 0.665 Jupiter-mass giant planet orbiting a 0.39 Solar-mass M dwarf. We apply a hierarchical retrieval framework incorporating an atmospheric model, a parametric stellar contamination model, and a Gaussian process (GP) to capture residual structure not explained by these deterministic components. We find that the inferred atmospheric properties are model-dependent: retrievals that treat stellar contamination deterministically yield a constrained CH4 abundance corresponding to a sub-solar metallicity that would challenge standard expectations from both core accretion and gravitational instability, along with potentially elevated CO and CO2 abundances that would require chemical disequilibrium. However, residual wavelength-correlated structure suggests the deterministic model is incomplete. Including a GP to marginalize over this structure broadens the atmospheric posterior distributions, preventing robust constraints on the atmospheric composition and highlighting the challenge of characterizing giant planet atmospheres around M dwarfs. We demonstrate that an eclipse observation could clarify these model-dependent ambiguities: detected emission features would constrain the planet's metallicity and test formation scenarios, while a featureless spectrum would confirm stellar contamination dominates the transmission spectrum, providing an empirical M dwarf contamination spectrum.

One of the forefront goals in the field of exoplanets is the detection of an atmosphere on a temperate terrestrial exoplanet, and among the best suited systems to do so is TRAPPIST-1. However, JWST transit observations of the TRAPPIST-1 planets show significant contamination from stellar surface features that we are unable to confidently model. Here, we present the motivation and first observations of our JWST multicycle program of TRAPPIST-1 e, which utilize close transits of the airless TRAPPIST-1 b to model-independently correct for stellar contamination, with the goal of determining whether TRAPPIST-1 e has an Earth-like mean molecular weight atmosphere containing CO2. We present our simulations, which show that with 15 close transit observations, we will be able to detect this atmosphere on TRAPPIST-1 e at Delta lnZ=5 or greater confidence assuming we are able to correct for stellar contamination using the close transit observations. We also show the first three observations of our program. We find that our ability to correct for stellar contamination can be inhibited when strong stellar flares are present, as flares can break the assumption that the star does not change meaningfully between planetary transits. The cleanest observation demonstrates the removal of stellar contamination contribution through an increased preference for a flat line over the original TRAPPIST-1 e spectrum, but highlights how minor data analysis assumptions can propagate significantly when searching for small atmospheric signals. This is amplified when using the signals from multiple planets, which is important to consider as we continue our atmospheric search.

We report the discovery and characterisation of three transiting warm Jupiters: TIC 147027702b, TIC 245076932b, and TIC 87422071b. These systems were initially identified as transiting candidates using light curves generated from the full-frame images of the TESS mission. We confirmed the planetary nature of these objects with ground-based spectroscopic follow-up observations using FEROS and the new PLATOSpec spectrograph attached to the ESO 1.52 m telescope at the La Silla Observatory, and with ground-based photometric observations of the Observatoire Moana, Las Cumbres Observatory Global Telescope and ASTEP. From a global fit to the photometry and radial velocities, we determine that the planet TIC 147027702b has a low-eccentricity orbit (e = 0.13 ± 0.05) with a period of 44.4 days, a mass of 1.09−0.13+0.07 MJ, and a radius of 0.98 ± 0.06 RJ. TIC 245076932b has a moderately low mass of 0.51 ± 0.05 MJ, a radius of 0.97 ± 0.05 RJ, and an eccentric orbit (e = 0.43 ± 0.02) with a period of 21.6 days. TIC 87422071b has a mass of 1.29 ± 0.10 MJ, a radius of 0.97 ± 0.08 RJ, and a slightly eccentric orbit (e = 0.12 ± 0.07) with a period of 11.3 days. These well-characterised warm Jupiters expand the currently limited sample of similar gas giants and provide valuable benchmarks for testing models of giant-planet formation, migration, and tidal evolution.

Context. Warm Jupiters are excellent case studies for the investigation of giant planet internal structures and formation theories. However, the sample of long-period transiting giants is still small today for a better understanding of this population. Aims. Starting from a single transit found in the Transiting Exoplanet Survey Satellite (TESS) data, we confirm the planetary nature of the signal and measure its orbital parameters, mass, and radius. We put this system in the context of long-period giant transiting planets and analyzed the viability to sustain atmospheric or dynamical follow-up. Methods. We carried out a spectroscopic follow-up using FEROS and PLATOSpec to obtain precise radial velocities. We added a photometric follow-up with HATPI and Observatoire Moana to obtain a more precise estimate of the orbital period. We derived the orbital and physical parameters through a joint analysis of this data. Results. We report the discovery and characterization of TIC65910228b, a transiting warm Jupiter with a mass of 4.554 ± 0.255 M_J and a radius of 1.088 ± 0.061 R_J, orbiting an evolved F-type star every ∼ 180.52 days in an eccentric orbit (e = 0.25 ± 0.04). Conclusions. This planet joins a still under-explored population of long-period (P > 100) massive (M_p > 4 M_J) transiting giant planets, being one of the few with a mild eccentricity. This target is a nice example of the potential of single-transit events to populate this region of the parameter space.

Context. Characterization of warm giants is crucial to constrain giant planet formation and evolution. Measuring the mass and radius of these planets, combined with their moderated irradiation, allows us to estimate their planetary bulk composition, which is a key quantity to comprehend giant planet formation and structure. Aims. We present the discovery of two transiting warm giant planets orbiting solar-type stars from the Transiting Exoplanet Survey Satellite (TESS), which were characterized by further spectroscopic and photometric ground-based observations. Methods. We performed a joint analysis of photometric data with radial velocities to confirm and characterize TOI-883 b and TOI-899 b, two sub-Saturns orbiting solar-like stars. Results. TOI-883 b and TOI-899 b have masses of 0.123 ± 0.012 M_J and 0.213 ± 0.024 M_J, radius of 0.604 ± 0.028 R_J and 0.991 ± 0.044 R_J, periods of 10.06 d and 12.85 d and equilibrium temperature of 1086 ± 19 K and 1040 ± 19 K, respectively. Conclusions. While having similar masses, orbital periods and stellar host properties, these planets seem to have different internal compositions, which could point to distinct formation histories. Both planets are suitable targets for atmospheric studies to further constrain formation scenarios of planets in the Neptune-Saturn mass range

In transiting planetary systems, in which planetary sizes are accurately determined from transit observations, the presence of transit-timing variations1 (TTVs), especially when combined with radial velocity (RV) data, provides powerful constraints on masses and orbital eccentricities. Together, these measurements offer crucial insights into system architecture, formation mechanisms and dynamical evolution. We present long-term RV and transit/TTV monitoring of the relatively young star (age approximately 1 Gyr) TOI-201, revealing an exceptional multi-planet system composed of a hot super-Earth (SE) size planet transiting every 5.8 days, a warm Jupiter (WJ) on a 53-day orbit and an eccentric (e = 0.62) low-mass brown dwarf (BD) on an approximately 8-year orbit, with an estimated mass MBD of about 16 Jupiter masses. The BD is the longest-period transiting substellar object ever characterized by means of RVs and the only one known to be coplanar with inner planets. The architecture of this system suggests that the SE was formed isolated and in the innermost region of the gaseous disk. On the other hand, the orbital configuration of the outer companions suggests a nearly in situ formation of both objects, with the WJ forming in a dense inner disk. Alternatively, the BD might have formed farther out and migrated inward, while increasing its eccentricity owing to interactions with the disk.

We report the discovery of TOI-4507 b, a transiting sub-Saturn with a density <0.2 g cm(-3) on a 10(5) days prograde orbit around a 700 Myr old F star. The transits were detected using data from TESS as well as the Antarctic telescope ASTEP. A joint analysis of the light curves and radial velocities from HARPS, FEROS, and CORALIE confirmed the planetary nature of the signal, by limiting the mass to be below 20 M-circle plus at 95% confidence. The radial velocities also exhibit the Rossiter-McLaughlin effect and imply that the planet orbits the star in a prograde orbit with a sky-projected obliquity lambda=-15(-44)(+50 degrees )(divided by lambda divided by < 80 degrees at 3 sigma). With these characteristics, TOI-4507 is one of the longest-period systems for which the stellar obliquity has been measured, and the planet is among the longest-period and youngest "superpuff" planets yet discovered.

Determining the prevalence of atmospheres on terrestrial planets is a core objective in exoplanetary science. While M dwarf systems offer a promising opportunity, conclusive observations of terrestrial atmospheres have remained elusive, with many yielding flat transmission spectra. We observe four transits of the hot terrestrial planet TOI-1685 b using James Webb Space Telescope (JWST)'s Near Infrared Spectrograph (NIRSpec) G395H instrument. Combining this with the transit from the previously observed phase curve of the planet with the same instrument, we perform a detailed analysis to determine the possibility of an atmosphere on TOI-1685 b. From our retrievals, the Bayesian evidence favours a simple flat line model, indicating no evidence for an atmosphere on TOI-1685 b, in line with results from the phase curve analysis. Our results show that hydrogen-dominated atmospheres can be confidently ruled out. For heavier, secondary atmospheres we find a lower limit on the mean molecular weight of greater than or similar to 10, at a significance of similar to 5 sigma. Pure CO2, SO2, H2O, and CH4 atmospheres, or a mixed secondary atmosphere (CO + CO2 + SO2) could explain the data (Delta ln Z < 3). However, pure CH4 atmospheres may be physically unlikely, and the pure H2O and CO2 cases require a high-altitude cloud, which could also be interpreted as a thin cloud-free atmosphere. We discuss the theoretical possibility for different types of atmosphere on this planet, and consider the effects of atmospheric escape and stellar activity on the system. Though we find that TOI-1685 b is likely a bare rock, this study also highlights the challenges of detecting secondary atmospheres on rocky planets with JWST.

JWST is transforming our ability to characterize small exoplanets, from sub-Neptunes to rocky worlds. A key open question is whether highly irradiated rocky planets can retain atmospheres or are stripped bare by stellar irradiation-a boundary that remains to be mapped observationally. Here we present the first JWST secondary eclipse observations of the rocky exoplanet GJ 3473 b, obtained with MIRI F1500W photometry. Using four visits, we confidently detect the eclipse at an average depth of 186 +/- 45 ppm, somewhat lower than expected for a blackbody. We test a wide range of data reduction and analysis assumptions and provide new insights into MIRI detector settling behavior that will benefit future observations. We model a suite of airless surfaces with varied compositions, textures, and degrees of space weathering, as well as idealized atmospheric scenarios including the possibility of atmospheric collapse. Both atmospheric and bare-rock interpretations remain consistent with the data, but we exclude thick CO2 atmospheres, placing a 95% credible upper limit of 1.2-6.5 bar on the surface pressure. We also find tentative evidence for visit-to-visit variability in eclipse depth (33-371 ppm), though additional data are required to confirm this. Our results highlight the challenges and intrinsic degeneracies in interpreting MIRI F1500W eclipse measurements of rocky exoplanets, indicating that such observations alone may not uniquely distinguish between bare-rock and atmospheric scenarios. Future spectroscopic or phase-curve observations will be required to determine whether or not GJ 3473 b hosts a substantial atmosphere.

We present an implementation of the well-known and broadly used Generalized Lomb-Scargle Periodogram (GLS) which simultaneously takes into account individual offsets introduced in the data by different instruments: a "multi-instrument" GLS periodogram. While the algorithm itself is not new, the simple closed form implementation we provide, to our knowledge, is. We showcase an application of our multi-instrument GLS on radial-velocity data of the hot Jupiter TOI-481 b, whose period is recovered with a higher significance compared to the standard GLS approach. The code is available on GitHub.

Many of the most scientifically compelling exoplanets orbit bright nearby stars that exceed the brightness limits of existing JWST spectroscopic observing modes. To address this limitation, a new NIRCam Short Wavelength Grism Time-Series mode has been developed by combining the Dispersed Hartmann Sensor (DHS) with a new on-board multistripe detector readout capability. The DHS disperses the incoming light through multiple pupil sub-apertures, reducing the incident flux and providing slitless spectroscopy between approximately 1.0 and 2.3 um. The multistripe readout mode further increases the accessible brightness range (K 2.5 - 5.7 mag, depending on the spectral type of the object), with the previous limit being K 5.7 mag at 1.5 um, by reading only the detector regions containing the DHS spectra, reducing the detector frame time with the standard RAPID readout mode from 10.74 s to 1.36 s over even less when using smaller substripe sizes. Together with the simultaneous long-wavelength grism observations, the new mode provides spectroscopic continuous coverage from approximately 1.0 to 5.0 um for targets as bright as K 2.5 mag. We present the first results of on-orbit commissioning of this new observing mode with the final stage consisting of observations of a full transit of the exoplanet WASP-18b, which allowed us to demonstrate the feasibility of using NIRCam DHS for high-precision time-series observations. The commissioning presented in this paper marks the first deployment of the multistripe detector readout on JWST. Beyond NIRCam DHS, this new capability will be extended to other spectroscopic modes, including NIRISS SOSS and NIRSpec PRISM. Bright nearby stars host many of the highest-priority targets for exoplanet atmospheric characterization, making multistripe an important new capability for maximizing the scientific return of JWST.

Context. M-dwarf systems offer an opportunity to study terrestrial exoplanetary atmospheres due to their small size and cool temperatures. However, the extreme conditions imposed by these host stars raise a question about whether their close-in rocky planets are able to retain any atmosphere at all. Aims. The Hot Rocks Survey aims to answer this question by targeting nine different M-dwarf rocky planets spanning a range of planetary and stellar properties. Of these, LHS 1478 b orbits an M3-type star, has an equilibrium temperature of T-eq = 585 K, and receives 21 times Earth's instellation. Methods. We observed two secondary eclipses of LHS 1478 b using photometric imaging at 15 mu m using the Mid-Infrared Instrument on the James Webb Space Telescope (JWST MIRI) to measure thermal emission from the dayside of the planet. We compared these values to atmospheric models to evaluate potential heat transport and CO2 absorption signatures. Results. We find that a secondary eclipse depth of 138 +/- 53 ppm at the expected time for a circular orbit is preferred over a null model at 2.8 sigma, a moderate detection, though dynamical models do favour a non-eccentric orbit for this planet. The second observation results in a non-detection due to significantly larger unexplained systematics. Based on the first observation alone, we can reject the null hypothesis of the dark (zero Bond albedo) no atmosphere bare rock model with a confidence level of 3.3 sigma, though for A(B) = 0.2 the significance decreases to 2.1 sigma. The tentative secondary eclipse depth is consistent with the majority of the atmospheric scenarios we considered, spanning CO2-rich atmospheres with surface pressures from 0.1 to 10 bar. However, we stress that the two observations from our programme do not yield consistent results, and more observations are needed to verify our findings. The Hot Rocks Survey serves as a relevant primer for future endeavours such as the Director's Discretionary Time (DDT) Rocky Worlds programme.

We present the first emission spectrum of the hot Jupiter WASP-17 b using one eclipse observation from the JWST Near Infrared Imager and Slitless Spectrograph (NIRISS) Single Object Slitless Spectroscopy (SOSS) mode. Covering a wavelength range of 0.6–2.8 μ m, our retrieval analysis reveals a strong detection of H 2 O in WASP-17 b’s dayside atmosphere (6.4 σ ). Our retrievals consistently favor a supersolar dayside H 2 O abundance and a noninverted temperature–pressure profile over a large pressure range. Additionally, our examination of the brightness temperature reveals excess emission below 1 μ m, suggesting the possibility of a high internal temperature (600–700 K) and/or contributions from reflected light. We highlight that JWST emission spectroscopy retrieval results can be sensitive to whether negative eclipse depths are allowed at optical wavelengths during light-curve fitting. Our findings deepen our understanding of WASP-17 b’s atmospheric composition while also highlighting the sensitivity of our results to pressure–temperature profile parameterizations. This work is part of a series of studies by our JWST Telescope Scientist Team (TST), in which we will use Guaranteed Time Observations to perform Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (DREAMS).

We report the discovery and characterization of three transiting giant planets in the TIC 118798035 system. The three planets were identified as transiting candidates from data of the TESS mission and confirmed with ground-based photometric transit observations along with radial velocity variations obtained with FEROS, HARPS, and ESPRESSO. The three planets present transit timing variations (TTVs). We performed an N -body orbital fitting to the TTVs and radial velocities, finding that TIC 118798035 b is a warm low-density Neptune with a mass of 0.0250 ± 0.0023 M _J , a radius of 0.655 ± 0.018 R _J , and an orbital period of 11.507 days; TIC 118798035 c is a warm Saturn with a mass of 0.403 ± 0.024 M _J , a radius of 0.973 ± 0.023 R _J , and an orbital period of 22.564 days; and TIC 118798035 d is a warm Jupiter with a mass of 0.773 ± 0.052 M _J , a radius of 0.923 ± 0.044 R _J , and an orbital period of 48.925 days. The bulk metallicities of the three planets do not fully follow the mass–metallicity correlation found for the giant planets of the solar system, which hints at a somewhat different formation history for the planets of the TIC 118798035 system.

We present the detection and characterization of TOI-4994b (TIC 277128619b), a warm Saturn-sized planet discovered by the NASA Transiting Exoplanet Survey Satellite. TOI-4994b transits a G-type star (V = 12.6 mag) with a mass, radius, and effective temperature of M-star=1.005(-0.061)(+0.064)M(circle dot) , R-star=1.055(-0.037)(+0.040)R(circle dot) , and T-eff = 5640 +/- 110 K. We obtained follow-up ground-based photometry from the Las Cumbres Observatory and the Antarctic Search for Transiting ExoPlanets telescopes, and we confirmed the planetary nature of TOI-4994b with multiple radial velocity observations from the Planet Finder Spectrograph, CHIRON, High Accuracy Radial velocity Planet Searcher, Fiber-fed Extended Range Optical Spectrograph, and CORALIE instruments. From a global fit to the photometry and radial velocities, we determine that TOI-4994b is in a 21.5 day eccentric orbit (e = 0.32 +/- 0.04) and has a mass of M-P=0.280(-0.034)(+0.037)MJ , a radius of R-P=0.762(-0.027)(+0.030)R(J) , and a Saturn-like bulk density of rho(p)=0.78(-0.14)(+0.16)gcm(-3) . We find that TOI-4994 is a potentially viable candidate for follow-up stellar obliquity measurements. TOI-4994b joins the small sample of warm Saturn analogs and thus sheds light on our understanding of these rare and unique worlds.

Zodiacal light – arising from both the thermal emission and scattered sunlight by interplanetary dust – is the dominant component of the sky background in NIRISS Single Object Slitless Spectroscopy (SOSS) observations. The GR700XD grism disperses the zodiacal background across multiple diffraction orders, producing a characteristic two-dimensional, spectral order-dependent background pattern on the detector that reflects the combined contribution of overlapping orders. Observations reveal significant variability in background intensity driven by JWST's sky pointing and seasonal changes, underscoring the need for precise background subtraction during SOSS data reduction. Current methods rely on a generic background template derived during commissioning, scaled to match individual exposures. However, mis-scaled templates can leave behind structured residuals that may compromise the precision of exoplanet transit depth measurements. To improve background modeling, we conducted two calibration programs (PID 4479 and 6658) using the FULL frame readout mode and a 5-row by 2-column mosaic pattern to sample a range of sky positions. These observations enable empirical reconstruction of the sky background and provide detailed insights into its spatial and spectral characteristics. We present a library of empirically derived background templates and evaluate their performance, alongside the current template, by benchmarking against the PID 2113 dataset, which includes contemporaneous background exposures. This work supports aims to enhance background subtraction for SOSS time-series to achieve higher-precision exoplanet spectroscopy with JWST.