EXOA4
The goal of this session is to bring together the instrumentation and observational communities that are underpinning the future of this field. Contributors are invited to review ongoing programmes of discovery and characterisation of both exoplanet and circumstellar discs, to update on the progress of planned instrumentation programmes, and to present innovative ideas for future instrumentation.
The Programmable Liquid-crystal Active Coronagraphic Imager for the DAG telescope (PLACID) is the first adaptive coronagraphic instrument designed for direct exoplanet imaging. The term “adaptive” refers to its capability to dynamically re-program the coronagraphic focal-plane phase mask (FPM) in real time, adapting to evolving observing conditions through the use of a customized spatial light modulator (SLM). Operating across the H to Ks spectral bands, the SLM acts as a fully programmable FPM, allowing patterns to be updated or recentered entirely via software without any mechanical motion. This flexibility enables observers to choose from a variety of coronagraphic modes and optimize observations for specific scientific goals or instrument conditions.
PLACID was delivered to the Turkish National Observatories (TNO) at Atatürk University in Erzurum in March 2024. It was subsequently transported to summit and installed on the diffraction-limited Nasmyth platform of the 4-meter Turkish DAG telescope during the first half of 2025, followed by full cabling and successful functional verification by mid-2025.
The instrument is now located at an intermediate coronagraphic fore-optics stage between the TROIA extreme adaptive optics (XAO) system and the DIRAC HAWAII-1RG infrared detector of the DAG telescope. Assembly, Integration, and Validation (AIV) activities on the diffraction-limited Nasmyth platform have progressed significantly, with initial alignment of the TROIA XAO system and DIRAC detector beam path completed by the end of 2025. PLACID itself completed the AIV phase in February of 2026 and is due to pass Preliminary Acceptance by mid-2026, in parallel with the first adaptive optics loop-closing operations. The PLACID first light is anticipated for late summer or early autumn of 2026.
In preparation for initial science operations, the PLACID graphical user interface (GUI) has been finalized. The instrument’s expected discovery space has been evaluated using a combination of laboratory measurements obtained during factory acceptance testing and simulations that incorporate residual wavefront errors after adaptive optics correction. These results have been integrated into an updated exposure time calculator, which accounts for adaptive optics performance, achievable contrast, limiting magnitudes, and the coronagraphic inner working angle. Furthermore, a ground-based observation planning tool has been developed, that will comprehensively assist astronomers in planning high-contrast imaging observations, providing information such as transit/zenith time, moon position, expected airmass, rate of change in parallactic angle and much more.
PLACID’s primary scientific goal is the direct imaging of exoplanets and circumstellar disks in the Northern Hemisphere. A highlight science case aims at targeting compact multiple star systems in search of circumbinary companions or disks, often excluded by high-contrast imaging surveys in the past. To support this, new observing modes are under development to enable coronagraphic imaging of binary and multiple systems in combination with Angular Differential Imaging (ADI). These include implementations such as the binary Roddier & Roddier mask and, more recently, binary vortex masks, representing a novel approach in coronagraphy. The PLACID data reduction pipeline is based on the PynPoint high-contrast imaging framework and is fully prepared for on-sky data processing.
Additional instrument capabilities will be implemented following the first science observations after commissioning in 2026. These planned features include self-calibration of non-common path aberrations using a phase-shifting Zernike wavefront sensor, coronagraphic nulling optimized for binary and triple star systems compatible with ADI, and time-domain coherent differential imaging (CDI).
In this work, we present the PLACID instrument as delivered, along with its predicted discovery space, binary coronagraphy capabilities, observation planning tools, and current on-site status. Initial results from Nasmyth platform commissioning using the internal calibration source, as well as first on-sky performance, if available, will be discussed. The instrument is being prepared for on-sky commissioning in the second half of 2026, with routine science observations expected to begin in 2027.
How to cite: Tandon, R., Marquis, L., Lin, L., Öztürk Çetni, D., Potier, A., Baur, A., Jolissaint, L., and Kühn, J. G.: The PLACID Active Coronagraph: Commissioning, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-127, https://doi.org/10.5194/epsc2026-127, 2026.
We present the discovery of a multi-planet system that comprises three mini-Neptunes transiting the bright (V=9.56) late F-type star TOI-261. Based on the analysis of two TESS sectors, the system was initially found to host two transiting sub-Neptune-sized planets (TOI-261 b and c) on relatively short period orbits (P_b ≈ 3.4 days and P_c ≈ 10.2 days). We conducted an intensive radial velocity follow-up campaign of TOI-261 using the high-precision HARPS and PFS spectrographs.
We conducted an intensive radial-velocity follow-up campaign of TOI-261 using the high-precision HARPS and PFS spectrographs, which allowed us to spectroscopically confirm the two planets and measure their masses. Our HARPS Doppler observations led to the serendipitous discovery of a possible third sub-Neptune-mass planet on a longer period orbit (TOI-261 d). A reanalysis of the two TESS sector light curves led us to identify two single transit events (one per sector) likely originating from the HARPS-detected planet. We subsequently confirmed its transits through dedicated observations with the CHEOPS space telescope, yielding an orbital period of P_d ≈ 22.9 days.
This results in a well characterized system of three nearly equal sub-Neptunes lining up at the ridge of the Neptune desert and populating the so called “Neptune-savanna”. This rare system gives the opportunity to learn more about the origin and the evolution of Neptune size planets. We performed an internal structure modelling, an atmospheric stability and evolution analysis and a dynamical orbit analysis which we will present. The three sub-Neptunes are also promising targets for further atmospheric analysis with JWST.
How to cite: Grziwa, S. and the KESPRINT, CHEOPS: One for all, all for one: The TESS-HARPS-PFS-CHEOPS synergy reveals three mini-Neptunes transiting the late F-type star TOI-261, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-891, https://doi.org/10.5194/epsc2026-891, 2026.
Mauve is a small satellite designed and operated by Blue Skies Space to study stellar activity and variability, exoplanet hosts, hot stars, and exotic populations in binaries. The satellite features a 13 cm telescope and is designed to obtain spectrophotometric data of bright stars across the 200–700 nm wavelength range at a low resolution.
Mauve launched on 28 November 2025 and obtained first light on 9 February 2026. The data from the satellite will be delivered through a three-year collaborative science programme, providing researchers with thousands of observational hours each year to perform time-domain astronomy at different timescales.
Researchers participating in the science programme define the science goals with flexibility to update the observational plan as and when required. The science themes identified for the first year of operations are available here: https://doi.org/10.1093/rasti/rzag018.
During the commissioning phase, Mauve observed multiple targets to characterise early performance and calibrate the instrument. In this presentation, we will showcase the proposed science themes, initial performance of the satellite, analysis and interpretations of the commissioning observations and how to participate in the programme.
Learn more about Mauve: https://bssl.space/mauve.
How to cite: Raman Mohan, Y. B., Saba, A., Tennyson, J., Tessenyi, M., Tinetti, G., Archer, R., Wilcock, B., and Razin, S.: Mauve Science Programme: Year 1 Goals & Early Results, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-260, https://doi.org/10.5194/epsc2026-260, 2026.
The study of exoplanets beyond the snow line is essential to understand planetary formation mechanisms. In this context, gravitational microlensing is a particularly effective indirect detection method to identify cold and faint planets located at distances of approximately 1 to 10 AU from their host star. This work is part of the Nancy Grace Roman space mission, dedicated to the detection of exoplanets via gravitational microlensing. It aims to improve the mass measurement of terrestrial exoplanets detected through this method. The adopted approach combines the modeling of microlensing photometric light curves with the analysis of high-angular-resolution images obtained several years before or after the event peak. The lens mass–distance relations derived from these two analyses allow us to tightly constrain its physical parameters, such as the planetary mass. This approach, which can also be applied to Euclid observations and future Roman surveys, will contribute to a better demographic characterization of cold exoplanets in the Milky Way.
How to cite: Gilles, M., Ranc, C., and Beaulieu, J.-P.: Combining the Euclid and Roman space missions to measure the mass of cold terrestrial planets, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1215, https://doi.org/10.5194/epsc2026-1215, 2026.
Recent phase-curve observations with JWST have highlighted the strong potential of spectroscopic phase curves to constrain exoplanet atmospheric dynamics and chemistry, motivating renewed interest in the phase-curve capabilities of Ariel. Phase curves provide constraints on atmospheric dynamics, heat redistribution, and cloud properties. Ariel will uniquely enable simultaneous observations across all instrument channels, covering wavelengths from 0.5 to 7.8 μm during long-duration observations. However, these observations are highly sensitive to long-term instrumental systematics, including gain variations and pointing drifts. Such effects may arise from changes in the detector electronic state, primarily driven by temperature fluctuations, persistence, and crosstalk effects. These effects occur on timescales comparable to the variations in planetary emission observed throughout the orbit. As a result, degeneracies between the instrumental drift model and the planetary flux model are expected and may be difficult to disentangle.
This work investigates the ability to detrend these long-term drifts while preserving the underlying astrophysical signal. We use the Ariel Simulator ExoSim2 (Mugnai et al, 2025) framework to generate end-to-end simulations of Ariel phase-curve observations. A 1.5D radiative transfer model is first used to produce theoretical phase curves (Changeat et al, 2024), which are then injected into ExoSim2 to simulate the instrument and detector response. Because the in-flight behavior of instrumental gain drifts cannot be predicted precisely before launch, several parameterizations are adopted to model temporal gain variations.
We evaluate how accurately the science parameters can be recovered under different gain-drift scenarios through a complete end-to-end analysis, from the simulation to the fitted light-curve model for the full wavelength range of Ariel’s spectroscopic channels. This study provides new insights into the potential of Ariel for phase-curve science. Future work will extend this analysis to a wider range of variability sources, including stellar variability. Retrieval models will also be applied to the simulated phase curves in order to estimate the uncertainties on astrophysical parameters.
How to cite: Syty, A., Changeat, Q., Mugnai, L. V., Pascale, E., Beaulieu, J.-P., and Drossart, P.: Ariel Phase Curves Against Gain Drifts, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-538, https://doi.org/10.5194/epsc2026-538, 2026.
I will present the science case and payload of WALTzER (Wide-band Atmospheric Laboratory for Transiting Exoplanet Research), which is an ESA F-class mission concept recently submitted to ESA's F3 call. The mission is designed to characterise the atmospheres of planets outside our Solar System. Its primary goal is to study the composition, vertical structure, and evolution of exoplanet atmospheres by analysing them from their lower layers up to the part escaping to space. The payload uses a single 35 cm telescope to simultaneously direct light into three instrument channels: a near-ultraviolet spectrograph, a visible spectrograph, and a near-infrared photometer. This design is strategically important, as WALTzER will fill the critical observation gap in the UV spectrum that is anticipated after the Hubble Space Telescope is decommissioned, and it would be the first instrument covering simultaneously from the near-ultraviolet to the near-infrared. The mission is a partnership between ESA and a consortium of ten member states, which is co-led by Austria and Switzerland. WALTzER's data will directly complement observations from the JWST and Ariel missions by providing simultaneous near-ultraviolet and visible context to their results based on infrared observations. During its three-year nominal mission, WALTzER will function as a versatile observatory: in addition to surveying almost 100 exoplanets, it will support a broad range of scientific investigations in Solar System science and Galactic Astrophysics. To ensure wide scientific benefit, 25% of the available observing time will be allocated to the global community through open calls.
How to cite: Hakim, K.: WALTzER - Wide-band Atmospheric Laboratory for Transiting Exoplanet Research, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1355, https://doi.org/10.5194/epsc2026-1355, 2026.
High-precision astrometry is a powerful tool for detecting and characterizing Earth-like exoplanets within the habitable zones of nearby solar-type stars. This contribution focuses on the scientific objectives and instrumental implementation of high-precision astrometry for future missions, such as a medium-class mission like the Theia mission proposed to the European Space Agency (ESA) or an astrometric mode of the High Resolution Imager (HRI) instrument on NASA’s Habitable Worlds Observatory (HWO).
We will present scientific goals of these missions, including detecting Earth-mass exoplanets through sub-microarcsecond astrometric measurements and exploring the complementary role of astrometry in studying exoplanetary systems, their formation, and their dynamical environments. We will also discuss the instrumental challenges and solutions required to achieve the necessary precision, including detector calibration, optical distortion correction, and differential astrometry techniques.
Addressing both the scientific potential and technical implementation highlights how next-generation astrometric instruments will contribute to exoplanet discovery and characterization. High-precision astrometry is a powerful tool for detecting and characterizing Earth-like exoplanets in the habitable zones of nearby solar-type stars.
How to cite: Malbet, F.: High-Precision Astrometry for Exoplanet Detection, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-652, https://doi.org/10.5194/epsc2026-652, 2026.
The European Space Agency's (ESA's) PLAnterary Transits and Oscillations of stars (PLATO) mission is scheduled for launch in early 2027 and will deliver high-precision, long-duration photometry. Over its four-year nominal mission, its 26 cameras will produce a rich data set supporting the detection and characterisation of exoplanets, deeper understanding of stellar ages and evolution through asteroseismology, and a wide range of additional stellar physics and complementary science cases.
PLATO's first observation field is located in the galactic southern hemisphere and referred to as LOPS2, with a sky area covering approximately 49° x 49° and its centre located close to the Large Magellanic Cloud (see Figure 1). Given the plethora of data, PLATO will not download full-frame images (except at the beginning and end of observing quarters) but instead provide imagettes of high-priority targets, along with light curves and centroids produced on board for other cases.
Figure 1: PLATO's first observation field (LOPS2).
The PLATO Input Catalogue (PIC) has been carefully curated to meet all the science requirements of the mission for this field. It provides the complete set of potential targets for transit searches, asteroseismology, spacecraft guidance, instrument calibration, and science validation. Overall, the PIC contains on the order of 200,000 bright dwarf and sub-giant stars of spectral types FGK and M. In detail, the catalogue is composed of four tables covering all relevant sources in the LOPS2 field (see Figure 2). In addition, two supplementary tables are provided which list all contaminants in the field of view and cross-identifications with other astronomical catalogues.
Figure 2: Composition of the PLATO Input Catalogue (PIC).
PLATO's observational data products are structured into four distinct deliveries, which can range from imagettes, light curves, and centroids generated on board to a catalogue of confirmed exoplanets with radial velocity information (see Figure 3).
Figure 3: PLATO's data products.
The PLATO ArXiv (PAX) is the mission's central access point for all data products. It provides graphical user interfaces and command line tools that allow the worldwide community to explore, visualise, and download a wealth of PLATO information. This ranges from retrieving the PIC to science observations (once available), from catalogue information to advanced query results. Notably, as the first ESA Science archive ever, the PAX was already made available before the missions launch to host the PIC and list of contaminants in the field. Users can readily interact with these tools and catalogues to plan ahead for upcoming observations and data analysis.
The schedule for making data products publicly available will vary based on the target sample. For the inaugural observing quarter, the first data products will be released via PAX approximately nine months after the end of said quarter. For all subsequent observing quarters, the first releases are planned within six months after the end of each quarter (see Figure 4).
Figure 4: PLATO's data releases.
References
- Nascimbeni et al. (2022, A&A 658, A31) - LOPN1 and LOPS1
- Nascimbeni et al. (2025, A&A, 694, A313) - LOPS2
- LOPS2 PIC2.2.0.1 Release Notes
- LOPS2 PIC2.2.0.1 PIC Data Definition Document
- Montalto et al. (2026, preprint) - tPIC
- Nascimbeni et al. (2026, preprint) - tPIC Prime Sample
- Prisinzano et al. (2026, A&A, 706, A207) - tPIC P4 Sample
- Zwintz et al. (2026, preprint) - scvPIC
- Heller et al. (2026, preprint) - cPIC and fgPIC
- Cabrera et al. (2026, preprint) - Assessment of PLATO Science Performance
- PLATO Product Definition Document
- PAX (https://pax.esac.esa.int/plato/)
How to cite: Günther, M. N. and the PLATO Team: Leveraging PLATO's Data: Overview of Products, Releases, and Access, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1152, https://doi.org/10.5194/epsc2026-1152, 2026.
