James A. Blake

Measuring field‐aligned currents (FACs) using magnetic field observations provides a powerful means to probe the multi‐scale interactions between the magnetosphere, ionosphere and thermosphere. In this study, we benchmark the curlometer technique using Swarm spacecraft observations and simulations of the coupled magnetosphere‐ionosphere system. We begin by correlating current density curlometer estimates derived from Swarm tetrahedra with varying spatial scales and barycenter locations. This confirms an apparent departure from stationarity for FACs at spatio‐temporal scales below 100 km where measurements appear highly uncorrelated. We then analyze simulated magnetic perturbations, where four‐point measurements can always be constructed. This shows how, even at meso‐scales of hundreds of kilometers, time‐shifted FAC estimates can diverge significantly from this ground truth. In both observational and simulated data we find poor tetrahedral configurations can produce spurious perpendicular currents due to numerical instability in the inversion process. This can be mitigated using appropriate quality metrics and high‐quality FAC reconstructions still achieved with a tetrahedral face well‐aligned to the local magnetic field. These results highlight the dynamic nature of FACs at large as well as small scales, and underscore the substantial advantages of true four‐point observations for their accurate analysis.

Source extraction is a fundamental task in astronomical data analysis, yet existing methods are often specialized to specific instruments, spectral bands, or imaging conditions, which limits their generalizability. In this work, we propose Extract Anything for Astronomy (EAA), a unified and perception-driven framework that adapts the Segment Anything Model (SAM) into a general-purpose astronomical source-extraction system. By introducing domain-aware input reprojection and full fine-tuning of the feature encoder, we systematically bridge the substantial domain gap between natural images and astronomical data. EAA integrates two complementary extraction paradigms, i.e., interactive and automatic extraction, enabling flexible usage across a broad range of spectral regimes and representative imaging conditions. Extensive experiments on CANDELS (approaching 80% completeness for sources with H < 27 AB) demonstrate improved deblending capability, faint source detection, and extraction robustness. More importantly, we validate the generalizability of EAA across a wide range of spectral regimes, including ultraviolet (GALEX, >95% completeness for sources with near-UV < 21), ground-based visible-light observations (>90% completeness for sources with Gaia-G < 12), radio (FIRST, >95% completeness for sources with FPEAK > 5), and millimeter-wave (Atacama Large Millimeter/submillimeter Array) data. Compared with SExtractor, Morpheus, and SAM, EAA provides the more comprehensive functionality and stronger deblending and perceptual segmentation capabilities, while its main limitation is lower faint-source detection sensitivity than SExtractor. These results show that perception-driven segmentation based on foundation models can serve as a powerful and universal paradigm for astronomical source extraction, providing a scalable infrastructure for next-generation sky surveys, space domain awareness, and cross-band scientific analysis.

Detecting discrete space-target trajectories from optical image sequences is important for ground-based space situational awareness, but direct sequence processing can be computationally expensive and sensitive to weak target responses. This paper presents LeTD, a linearity-enhanced trajectory detection framework built on compact sequence-level projections and a YOLO11n oriented bounding box detector. The aligned image sequence is reduced to maximum, median, and temporal projection maps, and sine–cosine temporal encoding is used to inject frame-index information into the standard three-channel detector input. Additional angle and endpoint supervision terms are introduced to improve localization of sparse linear trajectories while keeping the YOLO11n-OBB backbone and detection head unchanged. On an expanded real test set containing 82 sequences and 155 trajectories, LeTD achieves a track detection rate of 0.7742, a complete track rate of 0.6903, and a false-component rate of 0.2055 per frame under a unified GT-centric trajectory protocol. The method requires 0.52 s per sequence on average on the evaluated workstation platform, including representation construction and detector inference.

The geosynchronous (GSO) debris environment is continually evolving. Regular monitoring of the region is consequently of great importance, though the trade-off between coverage and sensitivity makes this challenging for the population of optically faint debris, where collecting area becomes a pivotal factor. Surveys conducted with large-aperture telescopes have provided crucial insights into the nature of this largely uncharacterised population. In this paper, we revisit a survey conducted with the 2.54 m Isaac Newton Telescope (INT), presenting an overhaul of the astrometric calibration and object detection stages of the original analysis pipeline. We apply a blind stacking technique to boost target recovery, unearthing 25 tracklets previously missed by single-frame extraction methods, and pushing the sensitivity limit fainter by 1 magnitude. The same algorithm is applied to a contemporaneous dataset, captured with a 36 cm astrograph, enabling performance benchmarking through the attempted recovery of INT detections from commercial-off-the-shelf observations. We achieve sub-arcsecond astrometric accuracy through a combination of improved star trail centroiding and iterative distortion fitting, allowing short arc initial orbit solutions to be obtained. High-cadence light curves extracted for trailing detections indicate that faint fragments are proportionally more variable than bright derelicts, with many exhibiting photometric signatures of rapid tumbling, often straddling the image noise floor. Lastly, we present preliminary findings from a follow-up multi-national observation campaign, utilising telescopes in Australia, Japan and La Palma. As space traffic management concerns begin to extend beyond GSO altitudes, scientifically-driven surveys of high-altitude orbits have an important role to play in characterising the faint debris environment.

The European Space Agency is set to launch PLAnetary Transits and Oscillations of stars (PLATO), the third medium-class mission of its Cosmic Vision programme, in early 2027. Using the transit method, PLATO is expected to detect thousands of exoplanets orbiting bright, nearby stars of spectral types F5–K7. Although the mission is primarily designed to enable mass measurements via radial velocities, its precise photometry and long observational baselines may also permit the detection of transit timing variations (TTVs), which can provide complementary dynamical constraints in multiplanet systems. One possible PLATO observing scenario involves a 2-yr-long observation of a northern field that may partially or fully overlap with the original Kepler field, creating an opportunity to revisit known multiplanet systems with a photometric baseline exceeding 20 yr. We simulate PLATO observations of 152 Kepler host stars containing at least one planet with previously detected TTVs, yielding a sample of 361 transiting planets. Our CCD-level simulations incorporate realistic stellar variability and employ both aperture and PSF (point spread function)-fitting photometry, accounting for each target’s real photometric contaminants. While the extended temporal baseline offers the potential for improved dynamical constraints in favourable cases, our simulations show that this potential is strongest for carefully selected systems, as PLATO’s smaller collecting area and larger pixel scale limit the achievable per-transit precision relative to Kepler. We identify a subset of systems most likely to benefit from complementary dynamical constraints through PLATO observations.

The Earth’s upper atmosphere is highly sensitive to solar activity and the solar wind-magnetosphere interaction. Magnetospheric current systems close through the ionosphere, where ion-neutral collisions and enhanced energetic particle precipitation can significantly modulate the spatial and temporal variability of the atmosphere's outer extent. Unlike the many isolated in-situ measurements conducted by previous space missions, distributed observations of neutral particles, plasma, and magnetic fields by a tetrahedron of micro-satellites, combined with precise tracking of satellite orbital dynamics, provide the global perspective needed to disentangle the complex transfers of energy and momentum through the tightly coupled magnetosphere-ionosphere-thermosphere system.In this presentation, we outline the ROARS F3 mission architecture. This mission seeks to obtain the first full curlometer magnetic field and energetic particle precipitation measurements in low Earth orbit (LEO), alongside concurrent measurements of the ambient plasma and neutral populations across a range of altitudes, latitudes, and longitudes. The measurement strategy is designed to resolve and characterise the energy and momentum entering the upper atmosphere, the multi-scale pathways through which these are redistributed, and the feedback mechanisms coupling back to the broader geospace environment. A comprehensive ground segment will simultaneously provide context by relating information on D- and E-region dynamics to the in-situ measurements.