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.

We present the analysis of five long-period TESS Objects of Interest (TOIs), all orbiting Sun-like stars, with orbital periods exceeding one month. Initially identified by the Transiting Exoplanet Survey Satellite (TESS), we extensively monitored these targets with the Antarctic Search for Transiting Exoplanets (ASTEP), supported by other facilities in the TESS Follow-up Observing Program (TFOP) network. These targets occupy a relatively underexplored region of the period-radius parameter space, offering valuable primordial probes for planetary formation and migration as warm planets better maintain their evolutionary fingerprints. To characterise these systems, we leveraged high-resolution speckle imaging to search for nearby stellar companions, and refine stellar parameters using both reconnaissance spectroscopy and spectral energy distribution (SED) fitting. We combined TESS photometry with high-precision ground-based observations from ASTEP, and when available, included additional photometry and radial velocity data. We applied statistical validation to assess the planetary nature of each candidate and used Allesfitter to jointly model the photometric and spectroscopic datasets. We validate the planetary nature of three TOIs, including the two warm Saturns TOI-4507b (8.2 Earth radii, 104d) and TOI-3457b (10.0 Earth radii, 32.6d), as well as the warm sub-Neptune TOI-707b (2.4 Earth radii, 52.8d). The remaining two candidates are most consistent with eclipsing binaries, namely TOI-2404 and TOI-4404. These results help populate the sparse regime of warm planets, which serve as key tracers of planetary evolution, and demonstrate ASTEP's effectiveness as a ground-based follow-up instrument for long-period systems.

We identify two large-radius planets around the F-type star HD 114082 as the longest-period young transiting exoplanets known. From the first transit, detected by NASA's Transiting Exoplanet Survey Satellite (TESS), and a second dip, spotted by the Next-Generation Transit Survey (NGTS), we predicted midtransit times for HD 114082 b (planet b). We pinpoint its orbit (period P-b = 225.5504 +/- 0.0004 days) from a third transit captured with the ESA's CHaracterising ExOplanet Satellite and the upgraded Antarctic Search for Transiting ExoPlanets telescope (ASTEP+), alongside orbit-discriminating observations. Another dimming partly covered by ASTEP+ completes the four-transit series. We support with dynamical evidence the planetary nature of a deeper transit detected with TESS and NGTS, identifying planet c. Additionally, we reexamine the debris disk, fitting its excess emission with two dust components. Fundamental stellar parameters are inferred from stellar evolution models, while a joint modeling of photometric and radial velocity time series yields the planetary parameters, with masses further constrained using an N-body code. For planet b, the semimajor axis a(b) = 0.791 +/- 0.008 au, eccentricity e(b) approximate to 0, inclination i(b) = 89 . degrees 791 +/- 0.014, radius R-b = 1.046 +/- 0.014 R-J, and 95% confidence upper limit on its mass M-95%,M-b = 1.6 M-J. For planet c, a(c) = 0.99 - 0.04 + 0.03 au, e(c) approximate to 0, i(c) = 89 . degrees 701 +/- 0.011, R-c = 1.36 +/- 0.03 R-J, and M-95%,M-c = 2.0 M-J (0.24 M-J if adding transit-timing-variation constraints). They seem to be moderate-to-low-mass giants in nearly resonant, coplanar, circular orbits that formed in situ, or beyond the snow line, and migrated inward, shaping the disk.

We present the combined JWST/NIRSpec/G395H and NIRISS/SOSS transmission spectrum of a warm mini-Neptune, TOI-1130 b (3.66 R-circle plus, 19.8 M-circle plus, and T-eq similar to 825 K). It is part of a rare and unique multiplanet system, TOI-1130, which hosts an inner mini-Neptune and an outer hot Jupiter locked in a 2:1 mean motion resonance. From the transmission spectrum of TOI-1130 b we detect multiple molecules-H2O (7.5 sigma), CO2 (3.3 sigma), and SO2 (3.6 sigma), as well as a tentative detection of CH4 (similar to 2 sigma). We find a strong optical slope in the NIRISS/SOSS spectrum, which is consistent with TESS and CHEOPS transit depth measurements. From equilibrium chemistry retrievals we measure the atmospheric metallicity ( log Z/Z(circle dot) = 1.8( - 0.3 )(+ 0.4 )) and C/O ratio (<0.75 at 3 sigma level confidence) and constrain the atmospheric mean molecular weight, mu = 5.5 (- 0.8) (+ 1.3) amu. These constraints are consistent with self-consistent forward model grids. We detect no significant He I 1.083 mu m absorption signal and find a mass-loss rate upper limit of 10(11) g s(-1). The volatile-rich high mean molecular weight atmosphere of TOI-1130 b along with the "pebble-filtering" effect of the outer hot Jupiter supports the ex situ formation scenario beyond the water ice line and subsequent migration, coherent with its present orbital architecture. A volatile-rich formation scenario could also potentially explain the location of TOI-1130 b at the edge of the "radius cliff." This result hints that the mini-Neptune population may not have a homogeneous formation history; rather, volatile-rich ex situ formation also contributes to its population.

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.

Beyond orbital periods of 10 days, there is a dearth of known transiting gas giants. On longer orbits, planets are less affected by their host star, and become ideal probes of planet formation, migration and evolution. We report the discovery of a long period Neptune and two Saturns, each initially identified as single transits in the TESS photometry, and solved through additional transits from ground-based follow-up photometric observations by NGTS and ASTEP. High-resolution radial velocity mass measurements using CORALIE and HARPS confirm their planetary nature. From joint modelling of the photometric and spectroscopic data, we determine an orbital period of $43.12655_{-0.00017}^{+0.00012}~$days, radius of 3.65 ± 0.22 R⊕, and mass of $19.1_{-4.5}^{+4.9}~\mathrm{M_{\rm{\oplus }}}$ for NGTS-34 b, making it one of the longest period well-characterized transiting Neptunes. Orbiting a late F-type star, bright in the K-band (Kmag ≃ 7.9), it is amenable for cool atmosphere studies using JWST or Ariel. TOI-4940 b is a small Saturn on a $25.867811_{-0.000056}^{+0.000058}~$day orbit with a radius of 6.61 ± 0.37 R⊕ and an upper mass limit <89 M⊕. NGTS-35 b(=TOI-6669 b) is a larger Saturn on a 25.241192 ± 0.000022 day, moderately eccentric orbit ($e = 0.192_{-0.033}^{+0.037}$), with a radius of 10.90 ± 0.65 R⊕ and a mass of $152_{-19}^{+22}~\mathrm{M_{\rm{\oplus }}}$. With an assumed albedo A = 0.3, each of these planets has an equilibrium temperature below 700K, with NGTS-35 b especially cold at 450 K. These three giants add to the small but growing population of long period planets that can further our understanding of planet formation mechanisms.

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.

Studying planetary interactions in exoplanet systems informs theories of planet formation and evolution, providing essential context for understanding our own solar system. We combine spectroscopy, transit photometry, transit timing variations, and astrometry to characterize the TOI-201 system. The cotransiting system consists of a super-Earth, warm Jupiter, and massive companion at 5.8-, 53-, and 2900-day orbital periods, respectively. We perform dynamical simulations to study the past and future of the system. von-Zeipel-Kozai-Lidov oscillations emerge as the most plausible scenario to explain the outer companion's high orbital eccentricity, with planet-planet scattering a possible but less likely contender. Because of nonzero mutual inclinations between the planets, the system is visibly evolving on very short timescales, with the current cotransiting configuration ending in 200 years.

Context. Long-period transiting planets are essential edge-cases for understanding exoplanet formation and evolution. Their detection is challenging due to the infrequent nature of their transits, making every observation of these objects very valuable. Aims. Our goal is to confirm and further characterise the long-period planetary candidate TOI-4409 b (initially identified by TESS) through additional observations using the Antarctica-based ASTEP telescope, supplemented with CHAT, OMES, LCOGT, and PEST light-curve data and radial-velocity (RV) measurements collected with the HARPS, FEROS, and PFS instruments. Methods. We jointly analysed the photometric data from eight TESS, four ASTEP, one CHAT, two OMES, four LCOGT, and one PEST light curve(s), and RV data from the HARPS, FEROS, and PFS instruments, covering observations from 2018 to 2024. Results. TOI-4409 b is a bona fide puffy warm super-Neptune exoplanet with a planet radius of 7.44 ± 0.19 R⊕ and a mass of 0.047 ± 0.017 MJ (3σ upper limit <0.095 MJ) orbiting a low-mass main-sequence star (effective temperature of 4928 ± 48 K and a stellar radius of 0.720 ± 0.018 R⊙) with a period of 92.49179 ± 0.00010 days. The integration of various observational methods and consistent transit signals across multiple instruments confirms the planetary nature of TOI-4409 b. The combined transit, imaging, chromaticity, and RV evidence supports the confirmation of the planet. Conclusions. With a radius of 7.44 ± 0.19 R⊕ and a low bulk density of 0.20 ± 0.07 g cm−3, TOI-4409 b occupies a sparsely populated region of parameter space among warm, puffy super-Neptunes on long-period orbits. The detection of candidate transit timing variations with an ~10-minute semi-amplitude hints at the presence of an additional body in the system. The favourable host-star brightness and extended transit duration (~7 hours) make TOI-4409 b a promising target for atmospheric characterisation with JWST and Ariel.

Gas giant planets with periods 20 < P < 300 d orbiting Sun-like stars are a relatively uncommon outcome of planetary formation, and key questions about the nature and formation of this subpopulation remain unanswered. Theoretical models for the location of their formation ( in situ or ex situ ) and for their subsequent migration predict different outcomes in terms of planet masses and eccentricities, indicating that observations have a key role to play in disentangling their histories. In this work, we present the discovery and confirmation of a pair of long-period Jupiter-sized planets transiting an F7 star: TOI-791 b is a 0.993 +/- 0.033 R-Jup planet on a 139.29931(-0.00012)(+0.00011) d orbit, and TOI-791 c, a 1.155 +/- 0.040 R-Jup planet on a 232.01570(-0.00071 )(+0.00067)d orbit. The two planets are within 0.07 per cent of a second-order 5:3 period commensurability leading to transit timing variations (TTVs) of up to 50 min. We confirm their planetary nature using ground-based photometry, including multiple full detections of the > 11 h transits of both TOI-791 b and c from Antarctica with ASTEP, making these the longest-duration transits ever observed in their entirety from the ground. Our detailed analysis of the TTV signal allows us to measure dynamical masses for both planets, which yield densities of rho(b) = 0.038 +/- 0.008 g cm(-3) and rho(c) = 0.047 +/- 0.006 g cm(-3), indicating that TOI-791 b and c are two of the lowest density giant planets ever detected. While these measurements are robust, further follow-up is needed to fully characterize the TTV signal and the architecture of the system.

Context. We present the analysis of five long-period TESS Objects of Interest (TOIs), all orbiting Sun-like stars, with orbital periods exceeding one month. Initially identified by the Transiting Exoplanet Survey Satellite (TESS), we extensively monitored these targets with the Antarctic Search for Transiting Exoplanets (ASTEP), supported by other facilities in the TESS Follow-up Observing Program (TFOP) network. Aims. These targets occupy a relatively underexplored region of the period-radius parameter space, offering valuable primordial probes for planetary formation and migration as warm planets better maintain their evolutionary fingerprints. Methods. To characterise these systems, we leveraged high-resolution speckle imaging to search for nearby stellar companions, and refine stellar parameters using both reconnaissance spectroscopy and spectral energy distribution (SED) fitting. We combined TESS photometry with high-precision ground-based observations from ASTEP, and when available, included additional photometry and radial velocity data. We applied statistical validation to assess the planetary nature of each candidate and used allesfitter to jointly model the photometric and spectroscopic datasets. Results. We validate the planetary nature of three TOIs, including the two warm Saturns TOI-4507 b (8.2 R⊕, 104 d) and TOI-3457 b (10.0 R⊕, 32.6 d), as well as the warm sub-Neptune TOI-707 b (2.4 R⊕, 52.8 d). The remaining two candidates are most consistent with eclipsing binaries, namely TOI-2404 and TOI-4404. Conclusions. These results help populate the sparse regime of warm planets, which serve as key tracers of planetary evolution, and demonstrate ASTEP’s effectiveness as a ground-based follow-up instrument for long-period systems.

The Sun is depleted in refractory elements compared to nearby solar twins, which may be linked to the formation of giant or terrestrial planets. Here we present high-resolution, high signal-to-noise spectroscopic data for 17 solar-like stars hosting planets, obtained with Magellan II/MIKE, to investigate whether this depletion is related to planet formation. We derive stellar parameters, including stellar atmosphere, age, radius, mass, and chemical abundances for 22 elements from carbon to europium through line-by-line differential analysis. Our uncertainties range from 0.01 dex for Fe and Si to 0.08 dex for Sr, Y, and Eu. By comparing the solar abundances to those of the 17 stars, we investigate the differential abundance ([X/Fe] solar –[X/Fe] star ) versus condensation temperature ( T c ) trend. In particular, we apply Galactic chemical evolution corrections to five solar twins within the full sample. Our results conform to previous studies that the Sun is relatively depleted in refractory compared to volatile elements. For both five solar twins and the rest of the solar-like stars, we find that all stars hosting known gas giant planets exhibit negative T c trend slopes, suggesting that the Sun is relatively depleted in refractory elements compared to similar giant planet-hosting stars. Additionally, we find no correlation between T c trend slopes and the total mass of detected terrestrial planets in each system, suggesting that terrestrial planet formation may not be the cause of refractory element depletion in the Sun.

We report the discovery and characterization of TOI-2005b, a warm Jupiter on an eccentric (e 0.59), 17.3-day orbit around a V_mag = 9.867 rapidly rotating F-star. The object was detected as a candidate by TESS and the planetary nature of TOI-2005b was then confirmed via a series of ground-based photometric, spectroscopic, and diffraction-limited imaging observations. The planet was found to reside in a low sky-projected stellar obliquity orbit (lambda = 4.8 degrees) via a transit spectroscopic observation using the Magellan MIKE spectrograph.TOI-2005b is one of a few planets known to have a low-obliquity, high-eccentricity orbit, which may be the result of high-eccentricity coplanar migration. The planet has a periastron equilibrium temperature of 2100 K, similar to some highly irradiated hot Jupiters where atomic metal species have been detected in transmission spectroscopy, and varies by almost 1000 K during its orbit. Future observations of the atmosphere of TOI-2005b can inform us about its radiative timescales thanks to the rapid heating and cooling of the planet.

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.

We present Cryoscope, a new 50 deg 2 field-of-view, 1.2 m aperture, K dark survey telescope to be located at Dome C, Antarctica. Cryoscope has an innovative optical–thermal design wherein the entire telescope is cryogenically cooled. Cryoscope also explores new detector technology to cost-effectively tile the full focal plane. Leveraging the dark Antarctic sky and minimizing telescope thermal emission, Cryoscope achieves unprecedented deep, wide, fast, and red observations, matching and exceeding volumetric survey speeds from the Ultraviolet Explorer, Vera Rubin Observatory, Nancy Grace Roman Space Telescope, SPHEREx, and NEO Surveyor. By providing coverage beyond wavelengths of 2 μ m, we aim to create the most comprehensive dynamic movie of the most obscured reaches of the Universe. Cryoscope will be a dedicated discovery engine for electromagnetic emission from coalescing compact binaries, Earth-like exoplanets orbiting cold stars, and multiple facets of time-domain, stellar, and solar system science. In this paper, we describe the scientific drivers and technical innovations for this new discovery engine operating in the K dark passband, why we choose to deploy it in Antarctica, and the status of a fifth-scale prototype designed as a Pathfinder to retire technological risks prior to full-scale implementation. We plan to deploy the Cryoscope Pathfinder to Dome C in 2026 December and the full-scale telescope by 2030.

Stars such as the Sun expel their outer layers and form planetary nebulae (PNe) as they evolve into white dwarfs. PNe exhibit diverse morphologies, the origins of which are not fully understood. PNe with OH (OHPNe) and H 2 O (H 2 OPNe) masers are thought to be nascent PNe. However, the number of known OHPNe and H 2 OPNe remains small, and only in eight cases has the position of the maser emission been found to coincide with the PN, using the high astrometric accuracy of interferometric observations. In order to identify more OHPNe and H 2 OPNe, we used public databases and our own ATCA/VLA observations to match the positions of OH and H 2 O masers with known PNe and radio continuum emitters, considering radio continuum emission as a possible tracer of the photoionized gas that characterizes PNe. Here we report the confirmation of positional coincidence of maser emission with one more PN, and 12 PN candidates. Moreover, we have confirmed three evolved stars as ‘water fountains’ (WFs) hosting H 2 O masers. These WFs are associated with radio continuum emission, but their possible nature as PNe has not yet been confirmed. Although a final characterization of maser-emitting PNe as a group still requires confirmation of more objects, their distribution in the infrared color-color diagrams suggests that they are a heterogeneous group of PNe. In particular, the new OHPN IRAS 07027–7934 has been reported to contain a late [WC]-type central star, while the maser emission implies an O-rich envelope. This property is found in only one other known maser-emitting PN, although we found evidence that other confirmed and candidate OHPNe may also have mixed chemistry, since they show emission from polycyclic aromatic hydrocarbons. The new WF IRAS 18443–0231 shows radio continuum that is dominated by strong and variable non-thermal emission, as in magnetized outflows.

Stars such as the Sun expel their outer layers and form planetary nebulae (PNe) as they evolve into white dwarfs. PNe exhibit diverse morphologies, the origins of which are not fully understood. PNe with OH (OHPNe) and H2O (H2OPNe) masers are thought to be nascent PNe. However, the number of known OHPNe and H2OPNe remains small, and only in eight cases has the position of the maser emission been found to coincide with the PN, using the high astrometric accuracy of interferometric observations. In order to identify more OHPNe and H2OPNe, we used public databases and our own ATCA/VLA observations to match the positions of OH and H2O masers with known PNe and radio continuum emitters, considering radio continuum emission as a possible tracer of the photoionized gas that characterizes PNe. Here we report the confirmation of positional coincidence of maser emission with one more PN, and 12 PN candidates. Moreover, we have confirmed three evolved stars as 'water fountains' (WFs) hosting H2O masers. These WFs are associated with radio continuum emission, but their possible nature as PNe has not yet been confirmed. Although a final characterization of maser-emitting PNe as a group still requires confirmation of more objects, their distribution in the infrared color-color diagrams suggests that they are a heterogeneous group of PNe. In particular, the new OHPN IRAS 07027-7934 has been reported to contain a late [WC]-type central star, while the maser emission implies an O-rich envelope. This property is found in only one other known maser-emitting PN, although we found evidence that other confirmed and candidate OHPNe may also have mixed chemistry, since they show emission from polycyclic aromatic hydrocarbons. The new WF IRAS 18443-0231 shows radio continuum that is dominated by strong and variable non-thermal emission, as in magnetized outflows.

TOI-1227 b is an 11 Myr old validated transiting planet in the middle of its contraction phase, with a current radius of 0.85 R$_J$. It orbits a low-mass pre-main sequence star (0.170 M$_\odot$, 0.56 R$_\odot$) every 27.4 days. The magnetic activity of its young host star induces radial velocity jitter and prevents good measurements of the planetary mass. We gathered additional transit observations of TOI-1227 b with space- and ground-based telescopes, and we detected highly significant transit-timing variations (TTVs). Their amplitude is about 40 minutes and their dominant timescale is longer than 3.7 years. Their most probable origin is dynamical interactions with additional planets in the system. We modeled the TTVs with inner and outer perturbers near first and second order resonances; several orbital configurations provide an acceptable fit. More data are needed to determine the actual orbital configuration and eventually measure the planetary masses. These TTVs and an updated transit chromaticity analysis reinforce the evidence that TOI-1227 b is a planet.

Dome-C in the Antarctic Plateau is a privileged site for Astronomy, with one of the lowest concentrations of water vapor in the world, providing a pristine atmospheric window for IR observations. Together with the long winter nights, this allows for extended continuous observational campaigns. At the Concordia Station, ASTEP has taken advantage of the weather and long nights to observe long-period transiting exoplanets for over a decade. With the Cryoscope Pathfinder we now plan to take advantage of the dark IR window between 2.35 and 2.55𝜇m. The unique design of Cryoscope Pathfinder is optimized for a very wide field of view and very thermal background. It is a cryogenic 0.26 m telescope designed for observations in K-dark with a field of view of 16 deg^2. This is the first step for a much more ambitious project, the full scale 1-meter class Cryoscope telescope, with a field of view of 50 deg^2. The initial science drivers are the study of exoplanets and of the infrared transient sky, where it will play a major role in the localization of gravitational wave sources. Furthermore, many other science topics will be enabled by Cryoscope and through synergies with other surveys.

Young (<500 Myr) planets are critical to studying how planets form and evolve. Among these young planetary systems, multiplanet configurations are particularly useful, as they provide a means to control for variables within a system. Here, we report the discovery and characterization of a young planetary system, TOI-1224. We show that the planet host resides within a young population we denote as MELANGE-5. By employing a range of age-dating methods—isochrone fitting, lithium abundance analysis, gyrochronology, and Gaia excess variability—we estimate the age of MELANGE-5 to be 210 ± 27 Myr. MELANGE-5 is situated in close proximity to previously identified younger (80–110 Myr) associations, Crius 221 and Theia 424/Volans-Carina, motivating further work to map out the group boundaries. In addition to a planet candidate detected by the TESS pipeline and alerted as a TESS object of interest, TOI-1224 b, we identify a second planet, TOI-1224 c, using custom search tools optimized for young stars ( Notch and LOCoR ). We find that the planets are 2.10 ± 0.09 R ⊕ and 2.88 ± 0.10 R ⊕ and orbit their host star every 4.18 and 17.95 days, respectively. With their bright ( K = 9.1 mag), small ( R * = 0.44 R ⊙ ), and cool ( T eff = 3326 K) host star, these planets represent excellent candidates for atmospheric characterization with JWST.