We draw a bow over developments in X-ray optics in the last two decades, relevant to high-resolution imaging, and sketch a potential path to future space telescopes in that energy range. In terms of aberrations and focal length, (Wolter) mirrors and diffractive-refractive transmission optics complement each other: near diffraction-limited (milli-arcsec or less) capabilities of the latter come at the expense of an inexpedient lens-detector distance of at least 100 km. Nonetheless, the predicted performance of “hybrid” doublets inspired their realization on a small scale: a(po)chromatic assemblies operate at synchrotron and free-electron laser facilities. Such lenses transform the planar wavefront to a sphere – or vice versa, when a zone plate is applied to test an X-ray telescope. Like in micro- or spectroscopy, figure errors of the mirror shape manifest themselves in blurry focal spots. Besides refractive phase plates to compensate for the wavefront deformation, an all-diffractive method modifies the Fresnel grooves where the narrow spectral bandwidth is acceptable. In any case, the reflective surface profile should be determined in-situ and at wavelength. We present a sensitive but robust technique to unveil perturbations of an axisymmetric XUV or X-ray mirror. Developed for a cm-sized ellipsoid, the method compares two CCD measurements of defocused intensity distributions. An algorithm extracts the geometrical phase precisely, limited only by the pixel size. As an advantage vs. other wavefront sensors, besides relaxed requirements on coherence, no radiation is lost at masks or gratings, beneficial for use at faint laboratory sources. For our tabletop setup, the wavefront error of 50 nm (rms) can be corrected by a “reflection zone plate”. We conclude with work in progress, conceptualizing “achromatic wavefront correction” by combining adapted grating- and prism-like components to correct the figure error of X-ray mirrors across an energy bandwidth accessible by a CCD or CMOS camera.

X-ray ground calibration facilities are essential for developing, testing and calibrating optical systems, detectors and fully integrated telescopes. As missions strive for finer angular resolution and tighter error budgets, there is an increasing demand for methodologies to be harmonised across facilities and for the link between measurements and physics-based models to be strengthened. To this end, we are establishing a new IACHEC Ground Calibration Working Group with four practical goals: 1) cross-calibrating X-ray test facilities using a common reference optic; 2) benchmarking ray-tracing packages against a shared reference optic model; 3) verifying analysis methods against a curated master dataset; and 4) providing guidance for ground calibration plans for forthcoming missions. This allows where necessary and possible, the distribution of calibration activities between facilities. Expected outcomes include shared standards, traceable error budgets and validated tools that will bolster confidence in pre-launch performance predictions. We will present exemplary cross-facility measurements of an eXTP mirror optic and an ATHENA mandrel optic, covering on- and off-axis PSF (half-energy width/encircled energy), effective area and vignetting. These measurements will then be comapared with ray-tracing predictions in order to quantify facility-to-facility systematics and validate the optics models and analysis pipelines.

High-angular-resolution, broadband X-ray optics are central to missions spanning 2–200 keV. This work presents an integrated approach that links a hybrid simulation–machine-learning framework for inverse design of depth-graded multilayer (DGM) coatings with targeted experiments and facility development. The model is trained on a large library of physics-based reflectivity simulations. It predicts key DGM parameters, bilayer count, thickness bounds, and grading profile, to maximize average reflectivity within a specified energy band and grazing-incidence angle, and it generalizes across material pairs and geometries while avoiding repeated re-optimization. To translate predictions into manufacturable prescriptions and quantify interface quality, a calibration study probes a Ni/C design optimized for 50–80 keV at 0.15°. Periodic multilayers (N = 5) with fixed bilayer spacings sampling the DGM bounds (35, 50, 65 Å) are deposited on silicon substrates via DC magnetron sputtering and assessed by 8.048 keV X-ray reflectometry over angular scans up to 2°, enabling growth-parameter tuning and comparison with simulations. Building on this calibration, a depth-graded Ni/C multilayer targeting 50–80 keV reflection has been deposited. In parallel, a vertical dual-linear magnetron sputtering chamber is being commissioned to support scalable deposition with a path toward high-angular resolution, hard X-ray full-shell optics. The combined pipeline aims to deliver high-performance DGM coatings for future high-energy astrophysics missions.

NewAthena is the next-generation X-ray telescope being developed by the European Space Agency (ESA) as an L-class mission, planned for adoption in 2027 and launch around 2038. Covering the 0.2–10 keV range, it will feature the largest X-ray optic ever built: a 2.6 m diameter, 12 m focal length system with more than 1 m² effective area at 1 keV. The optic is enabled by Silicon Pore Optics (SPO), developed by ESA, cosine, and partners, which assemble up to 600 mirror modules into a single lens. This talk presents the status of SPO production and the path to mass manufacturing.

The NASA Extreme Ultraviolet Explorer (EUVE) launched in 1992 was the first and last dedicated space telescope to operate in the EUV band. In addition to a whole sky survey, this successful mission collected the spectra of hundreds of objects but ultimately spectroscopy was limited by the sensitivity and resolving power of the spectrometer (~ 1 cm^2 and R~300). The EUV range is however important to understand the physical processes happening in million degree plasmas such as in hot white dwarf atmospheres, accretion processes, the interstellar medium and others. In addition, EUV radiation drives the atmospheric escape of all planets and is therefore critical to measure in order to understand the impact of host stars on the habitability potential of their exoplanets. Since the 1990s, technological advances have been made and are now enabling a renaissance for EUV missions, thanks in part to the possibilities offered by nanofabrication techniques to create high-efficiency diffraction gratings tailored to that wavelength range. We will summarize the recent advances made in the fabrication of such high-efficiency diffractive optics, their use case for upcoming NASA missions and their applicability in the X-ray regime.

V. Marsikova, P. Oberta, L. Pina, A. Inneman, R. Hudec Talk will be presented by L Pina Wolter type X-ray optics have been developed for many years for space applications/uses. We present and discuss the main results of the project focussed on the innovate replication technology for the production of replicated X-ray optics for the laboratory and synchrotron applications with small apertures of 10 to 40 mm. The achieved shape accuracy was better than 100 nm (RMS) over a 50 mm length and the micro-roughness was better than 2 nm (RMS) over a 10x10 µm area. Functional vacuum compatible samples with 3 various reflective layers (Au, Ni, Ru) were designed, manufactured and tested within the project. These layers are subsequently replicated, i.e. they are transferred to the inner wall of the self-supporting replica by an electroplating replication method. The innovation of the technology was represented by the introduction of 4i CNC nanotechnology. The potential application areas are laboratory, synchrotron, X ray lithography, laser plasma X ray imaging and spectroscopy.

Ladislav Pina, Peter Oberta and Rene Hudec . Talk will be presented by Ladislav Pina. Grazing incident X-ray and EUV optics (GIXO) find applications in astrophysics, laboratory hot plasma research, EUV lithography and in various imaging and spectroscopy laboratory systems. The basic design rules of grazing-incidence X-ray optics, including raytracing and mirror testing, are presented. Rotationally Symmetric Parabolic, Ellipsoidal, and Wolter mirrors as related to EUV and Soft X-ray sources were studied in detail. Source size, spectral range, magnification, geometry, materials and geometrical limitations are used as input data for calculations. Examples of mirrors designed with use of computer calculations and their experimental characterization are also included.

Laue-lenses may improve the signal to noise (S/N-) ratio in the sub-MeV gamma domain by one to two orders of magnitude relative to direct-view instruments like COMPTEL and COSI. But the lenses are only effective for point sources; for extended sources the S/N-ratio drop off rapidly. The drop in the S/N-ratio is not caused by a reduction of the diffraction efficiency of the lens crystals, but by an unavoidable deterioration of the focusing quality for off-axis photons related to Brag’s law and Darwin’s model for mosaic crystals. The use of Laue lenses will significantly improve the detectability of soft gamma emission from suspected sources localized at other wavelengths. The much-improved S/N-ratio will allow for timing and spectral studies inaccessible for direct-view instruments. Guidelines for the construction of future Laue-lens systems will be presented.

The Off-plane Grating Rocket Experiment (OGRE) is a NASA suborbital rocket mission for high-performance X-ray spectroscopy. The nominal payload utilizes lightweight, polished-Si optics fabricated by NASA's Goddard Space Flight Center, a reflection grating array fabricated at Penn State with key industrial collaborations, and an EM-CCD based camera fabricated by XCAM in collaboration with the Open University. In preparation for the nominal mission, we will fly a pathfinder rocket that swaps the polished-Si telescope out for the JET-X telescope. This is one of three telescopes originally made for Spectrum-x-gamma with one currently flying on Swift and one slated for Pathfinder-OGRE, being lent by the Italian Space Agency. Furthermore, given the large mass of the payload, an additional telescope option is being considered, short-focal-length Silicon pore optics. Here we report on the progress of the OGRE program, overview of the Pathfinder-OGRE mission, and updates on the nominal payload.

Results of optical tests of Schmidt lobster eye prototype module based on a new technology are presented. The technological concept offers precise assembly of optical mirrors, which is the key aspect to obtain sharp focal image. The prototype is designed for X-ray energies about 1keV. Dimensions and focal length of the prototype are chosen to allow boarding on CubeSat class Satellite. The module was tested on optical bench using visible light using LED as source , which is possible because glass plates coated with gold are used as mirrors. Images are acquired using Canon EOS 50D camera. The setup allows measurements in off-axis positions of the optics. FWHM and field of view are measured and compared to theoretic values.

The eXTP mission has finished the phase B study. In 2025, we have finished another phototype of the mirror module employing the pure nickel as the reflective layer, during the testing of the phototypes manufactured by Media Lario and us, we found additional loss of the effective area by 10%. In this way, we have rechecked the margin of the design of the effective area, and added 5 inner shells into the mirror module to increase about 40 cm2. Moreover, the thickness to radius ratio has also increased to 0.002 to manufacture the mirror shells with higher yield rates. The structural testing model and the SFA qualication model will be manufactured in the next year.

The “Deutsches Röntgen-Museum” in Remscheid (Germany) is the institution that uniquely and comprehensively explores and documents the life and work of Wilhelm Conrad Röntgen and the impact of his discovery. It preserves a collection of X-ray images taken by W. C. Röntgen during his research. Among them are three images of Röntgen's own hands and those of his wife, Anna Bertha. Three more images show Röntgen's hunting rifle, which he was able to analyze internally by using the new X-ray technology. These two series of historical pictures from the years 1895 and 1896 provide an outstanding illustration of the scientific revolution that Röntgen's discovery triggered especially in medicine and in materials science. Therefore, his discovery of X-rays ranks among the most groundbreaking scientific achievements of modern times. In April 2025, those very first recorded X-ray photographs were added on the UNESCO Memory of the World Register. The corresponding public ceremony took place on September 10, 2025 in Röntgen´s birth town Remscheid. Representatives of the German UNESCO Commission, of politics, and of the German Röntgen Society were present. UNESCO is thus honoring not only Röntgen's groundbreaking discovery of X-rays, but also the cultural, scientific, and technological implications of his early radiographs. The "Deutsches Röntgen-Museum" presents six famous historical X-ray documents to the public, which are now part of UNESCO´s Memory of the World Register.

Since ten years, Aschaffenburg University of Applied Sciences and the Czech technical university in Prague are now cooperating. During the recent decade, eleven joint projects have been executed, mainly targeting the development of astronomical X-ray optics. The bilateral cooperation also included the exchange of PhD students and scientists, cost compensation for conference participations, and the sponsoring of scientific conferences (AXRO and IBWS). The scientific output up to date are more than twenty joint publications and many individual conference contributions of the project partners in addition. The Bavarian-Czech Academic Agency (BTHA) has funded all of these projects. It is the goal of the Bavarian-Czech Academic Agency to support the academic collaboration in research and education and to contribute to an increased cooperation of the two neighboured countries Bavaria and Czech Republic in general. We will give a review on one decade of our Bavarian-Czech cooperation and on the scientific results of our joint projects on astronomical X-ray optics.

The Advanced X-ray Imaging Satellite (AXIS) is proposed as a next-generation X-ray observatory that combines high resolution over a large field of view with a large light-collecting area. AXIS utilises the latest developments in the construction of lightweight, segmented X-ray optics made of single-crystal silicon and relies on the manufacture of large-format CCDs with small pixels and a high readout rate as well as good spectral resolution for the detector. The mission was proposed by the University of Maryland and MIT as part of NASA's Probe programme and has been selected for a Phase A study. The launch is scheduled for 2032. The Max Planck Institute for Extraterrestrial Physics (MPE) is supporting the project in the design and qualification of the AXIS X-ray telescope. Initial X-ray optical tests on breadboard optics were already carried out in 2023 in the PANTER X-ray facility. As part of AXIS Phase A, optics modules with 16-18 mirror layers shall undergo a test programme comprising multiple X-ray tests as well as vibration and thermal tests. In parallel, structural and thermal calculations are performed, on the one hand in connection with the tests at module level and on the other hand for the complete X-ray optics, in order to be able to predict their performance under space conditions and to be able to counter any problems that arise by adapting the design.

The X and Gamma-ray Imaging Spectrometer (XGIS) is the high-energy monitor proposed for THESEUS (Transient High-Energy Sky and Early Universe Surveyor), a candidate mission within ESA M7 program aimed at exploring the transient high-energy sky for investigating the Early Universe and advancing in multi-messenger astrophysics. XGIS is designed to detect and localize transient X-ray and gamma-ray sources across a broad energy range (2 keV – 10 MeV), enabling high-resolution timing and spectroscopy. The instrument consists of two identical cameras, employing coded mask techniques to image the sky in the range 2–150 keV, while acting as a half-sky monitor in the 150 keV–10 MeV energy range. Its innovative detection system is based on Silicon Drift Detectors (SDDs) optically coupled to CsI(Tl) scintillator bars. This configuration, combined with a low-noise distributed electronics system (ORION-ASICs), enables spectroscopy over an unprecedentedly wide energy band within a single, modular, and compact device. The design of XGIS emphasizes modularity and robustness, with each camera integrating 100 detector modules that require extensive development, testing and qualification. The ongoing development of XGIS includes performance testing of the silicon sensors and the ORION readout chain, alongside optimization of the mechanical assembly. These efforts will lead to the construction of a second demonstrator module for XGIS, supported by ESA funding. In this poster we present the XGIS architecture and performance, and we will summarize the technological advancements since M5 Phase A, highlighting progresses made in the current M7 Phase A in terms of technological readiness.

Tianguan Satellite is a Chinese X-ray observatory dedicated to time-domain astronomy and high-energy astrophysics. The Follow-up X-ray Telescope, with its Chinese name "Fengxingtian", is one of the core payloads on the Tianguan Satellite. Fengxingtian is a China-led X-ray astronomical telescope, with the European Space Agency (ESA) and the Max-Planck Institute for Extraterrestrial Physics (MPE) participating through international cooperation. It consists of two identical telescope units, adopting multi-layer nested Wolter-I type X-ray focusing mirrors, and its focal plane is equipped with the latest PNCCD provided by MPE. A micro helium pulse tube has been developed to cool the PNCCD, achieving an on-orbit temperature stability of ±0.08°C. Having been in orbit for nearly two years, Fengxingtian has maintained stable operation and excellent performance. Characterized by a large field of view, high sensitivity, and low background noise, it can not only observe point sources but also deliver remarkable results in diffuse source observations, making significant contributions to the research of transient sources and astronomical observatory science.

In recent years there have been numerous efforts to build a constellation of small satellites which would provide an all-sky coverage and quick localization of gamma-ray bursts. One of the proposed missions is the CAMELOT constellation which triggered the development of a novel CsI scintillator-based detector read-out by silicon photomultipliers (SiPMs). The prototype of this detector has already been employed in three space missions; a 1U CubeSat GRBAlpha, its 2U successor GRBBeta, and a 3U CubeSat VZLUSAT-2. While GRBBeta, launched in July 2024, is still active, GRBAlpha deorbited in June 2025 and the re-entry of VZLUSAT-2 is expected by the end of 2025. In four years the latter two missions collected the largest CubeSat sample of gamma-ray transients with over 300 unique events. They demonstrated that routine observation of astrophysical gamma-ray transients by nanosatellites is not only feasible but can be a time and cost-effective contribution to large missions. I will present the variety of observed events and share the take-away messages for future projects.

Transmitting X-ray CCD data down to the lowest accessible energies poses significant challenges, as charge released by the absorption of a single photon may spread over several pixels, and accurate energy reconstruction requires the transmission of all charge components. Since many of these charge components lie close to the instrumental noise, it is unavoidable to transmit also some noise. The noise level is steeply rising towards low energies and requires to set a low energy threshold for the transmission. It may also exhibit substantial pixel to pixel variations, so that pixel-specific low energy thresholds are required to balance telemetry usage. Guided by the goal that the instrumental performance should not be limited by telemetry, we have developed an efficient data compression algorithm which takes all this into account. After having passed thorough tests on ground, this algorithm was activated soon after launch and has since then been used for the transmission of all the scientific eROSITA data.

The ASTRABAX ("Aschaffenburg Stratospheric Balloon Experiment") project team uses a multimodal platform to study radiation exposures in the upper atmosphere. The multimodal setup inside the balloons gondola allows flexibility to address current research questions with low expenditure in costs and manpower. Recently, two stratospheric balloons were flown to characterize the stratospheric radiation environment. The focus of the physical experiments is the observation of the UV-C spectral region using miniature UV-VIS spectrometers and cosmic ray dosimetry with a Geiger counter. The platform also contains samples of biological cells that are simultaneously exposed to low-dose radiation of different compositions of high-energy particles, gamma rays, and UV radiation. Investigations in such natural environment are of importance for human space flights, for comparable exposures on other objects of the solar system, and for astrobiology.

L. Amati, E. Bozzo, R. Hudec on behalf of the THESEUS consortium. The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large European collaboration under study by ESA since 2018 and currently one of the three candidate M7 mission for a launch in the late '30s. THESEUS aims at fully exploiting Gamma-Ray Bursts for investigating the Cosmic Dawn and as key phenomena for multi-messenger astrophysics. By providing an unprecedented combination of X-/gamma-ray monitors, on-board IR telescope and spacecraft autonomous fast slewing capabilities, THESEUS will be a wonderful machine for the detection, multi-wavelength characterization and redshift measurement of any kind of GRBs and many classes of X-ray transients, including high-redshift GRBs for cosmology (primordial low-mass/luminosity galaxies, first stars, cosmic re-ionization) and electromagnetic counterparts to sources of gravitational waves. Moreover, THESEUS will enable extreme and fundamental physics through unprecedented breakthrough measurements of GRB prompt and afterglow emission, as well as the detection and multi-eavelength characterization of many classes of high-energy transients. In all thses respects, THESEUS will thus provide an ideal synergy with the very large astronomical facilitiesof the future working in the e.m. (e.g., ELT, CTA, SKA, Athena) and multi-messenger (e.g., Einstein Telescope, Cosmic Explorer, km3NET). Talk will be presented on behalf of the THESEUS consortium by R. Hudec.

The enhanced X-ray Timing and Polarimetry mission-eXTP is a scientific space mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. One of the payloads is the Spectroscopic Focusing Array (SFA), an X-ray focusing telescope array. Its primary function is to achieve "spectroscopic-temporal" measurements with a high dynamic range and high signal-to-noise ratio. SFA consists of six Wolter-I grazing-incidence X-ray telescopes engineered for spectral, timing, and imaging studies within the 0.5 to 10 keV energy spectrum. Each telescope setup consists of a mirror module, an electron deflector, a filter wheel, and a focal plane camera. To achieve high energy resolution while controlling the overall complexity and cost of the satellite, silicon drift detectors (SDDs) are used, which have relatively easily achievable temperature control requirements. Five focal plane cameras are equipped with SDD, earning their telescopes the designation SFA-T ("T" for "Timing"), highlighting the SDDs' superior timing precision. Each of the SFA-T payload includes one filter wheel, one detector shielding box, and one detector box. Each SFA-T telescope includes a 19-cell SDD array, whose energy resolution is better than 180 eV@ 6 keV. The SDD detectors will be developed and contributed to the eXTP project by the Max Planck Institute for Extraterrestrial Physics (MPE). It offers a time resolution of 10 microseconds, and the dead time is anticipated to be under 5% for a source intensity around 1 Crab. We have completed all works of Phase B for the eXTP mission and transitioned to Phase C, where we are currently designing the Electrical and Functional Model and the Structural Thermal Model of the SFA-T camera.

The Einstein Probe (EP) mission is designed to detect mainly high-energy transients and variables, at unprecedented sensitivity and spatial resolution in the soft X-ray band, and to perform quick and deep follow-up observations in X-rays. EP is an international collaborative mission led by the Chinese Academy of Sciences, with partners of ESA, MPE and CNES. EP was launched on January 9, 2024. EP had completed the commissioning and in-orbit calibrations by July 2024. Since then, EP has started the nominal science operations phase. This talk will introduce the instrument performance, the science operations, and preliminary results with emphasis on the transients and variables detected. The Cycle 1 data will be released by the end of 2025.

Recent observations of the transient sky at all wavelengths are increasingly revealing the importance of the multi-messenger and multi-wavelength approach. The GRINTA hard X-ray observatory, proposed for launch around the middle of the next decade, is conceived as a small mission with good sensitivity, excellent angular resolution and fast follow-up capability for studying transient sources at timescales from ms to hours, at the same time ensuring optimal integration with multi-messenger networks. The GRINTA mission will carry two complementary payloads to cover in total the 5-10,000 keV band, that will detect and localize gamma-ray bursts covering ~ half the sky and will be able to perform imaging surveys with sub-arcmin resolution. GRINTA is aimed at a launch around the middle of next decade, to operate in synergy with the most powerful electromagnetic, gravitational wave and neutrino observatories.

An understanding of the expected point spread function of the SMILE/SXI instrument is valuable to enable modelling of the expected imaging results using Leicester's SXI End-to-End Simulator (SXI_SIM) and to predict the likely influence of strong x-ray sources from outside the nominal field of view due to higher reflection count modes. We will share a simple (spatially constant) PSF estimate based on limited empirical data of the central PSF (from the testing phase) which has been extended by simulated data to add the effect of higher reflections. We will also present the result of using extensions to the QSOFT simulation software to simulate spatial variation in the PSF generated across a wide field of view thus incorporating the expected vignetting effects due to the detector extent, the MPO array extent, the MPO support frame and occlusion by the inner and outer baffle structures of the straylight system at a given energy.

The decade of the 2030's promises significant advances in the understanding of gravitational wave (GW) sources due to increased sensitivity in current 2nd generation detectors and the advent of 3rd generation detectors, which anticipate 100s-1000s of binary neutron star (BNS) mergers per year. This huge increase in events will provide a better understanding of the short gamma-ray burst population and test various aspects of fundamental physics. However, to fully exploit the GW results requires electromagnetic (EM) observations, particularly at X-rays and soft gamma-rays to study the prompt emission as the merger occurs. We will present some questions raised by the first joint GW/EM detection (GW170817/GRB170817A) that can be addressed by the proposed GRINTA mission, which could fly in the mid-2030s.

We show that a Soft X-ray Imager (SXI) onboard the ESA-CAS satellite SMILE will be able to observe various types of mass accreting compact objects in the universe. We show that neutron stars accreting matter from their companions in binaries are promising targets for evaluating the possibilities of SXI. We present the typical features of the long-term activity of various X-ray binaries in the SXI/SMILE field of view. We also show that binaries with steady-state thermonuclear reaction onboard accreting white dwarfs, located in the Magellanic Clouds, are promising targets for SXI observations. We discuss how SXI can contribute to this branch.

The Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE) mission, a pioneering collaborative project between the European Space Agency and the Chinese Academy of Sciences, is set to revolutionize our understanding of solar wind-magnetosphere interactions. SMILE will employ a wide-field Soft X-ray Imager (SXI) to globally visualize the Earth's dynamic magnetosphere in response to solar wind variations. This technique exploits the solar wind charge exchange (SWCX) process, which generates soft X-ray emissions when highly-charged ions from the solar wind interact with neutral atoms in the Earth's exosphere. These emissions allow us to remotely sense large-scale structures with a novel approach, such as the magnetopause, cusps, and bow shock. This presentation will detail the development and capabilities of SMILE, including the recent progress of the whole mission and the Modeling Working Group (MWG).

GRBAlpha and VZLUSAT-2 CubeSats have been successfully operating and conducting scientific measurements in low Earth orbit for approximately four years. Both CubeSats had onboard gamma-ray detectors based on CsI(Tl) scintillator readout by silicon photomultipliers (SiPMs). SiPMs are becoming popular for scintillator-based gamma-ray detectors on CubeSats due to their low operating voltage, small size, linear response to low light intensity and fast response. However, SiPMs are prone to radiation damage, resulting in an increase in the dark count rate. Therefore, it is important to characterise their long-term performance in the space environment. We will report on the long-term changes in dark count rate and low-energy threshold of Hamamatsu S13360-3050 PE SiMPs. We have demonstrated that SiPMs can be used in the low Earth environment on a mission lasting beyond three years, and gamma-ray detectors on nanosatellites can routinely detect gamma-ray bursts.

The enhanced X-ray Timing and Polarimetry (eXTP) mission is a scientific space mission aimed at studying the state of matter under extreme conditions of density, gravity, and magnetism. The Spectroscopy Focusing Array (SFA), one of the two types of scientific instruments of the eXTP mission, is designed for spectral and timing observations in the 0.5 to 10 keV energy range. The SFA comprises 6 telescopes, 5 of which are identical. Each of these 5 telescopes mainly consists of one mirror assembly with a focal length of 5.25 m and a monolithic 19-pixel Silicon Drift Detector (SDD) array that acts as the focal plane detector. In order to evaluate the timing performance of the SFA telescopes, an time-varying X-ray source based on a grid pole-controlled X-ray tube was designed and integrated into in the 100-m X-ray Test Facility in China. This time-varying X-ray source can generate pulsed X-rays with short duration (e.g., 100 ns) or any X-ray light curve. In this report, we will present the design of the time-varying X-ray source and the test results of not only the SFA telescopes but also some already launched X-ray telescopes (GECAM, EP), including time resolution, time accuracy calibration (in Pulse mode), and time-varying response (in Light Curve mode).

The BEaTriX X-ray facility is now operational at INAF-Brera Astronomical Observatory, at the Merate seat. This innovative and one-of-the-kind X-ray facility generates a broad (6 cm x 17 cm), parallel, highly-polarized and uniform X-ray beam at the energy of 4.51 keV, in order to perform the systematic characterization of the NewAthena mirror modules in terms of angular resolution and effective area. We report in this talk the latest commissioning tests on a real mirror module and we compare the results with those achieved at other X-ray facilities, such as PANTER. We also report the advancements in the construction of the second short-arm beamline at the 1.49 keV energy, including the new X-ray source, the monochromators and the beam expanding crystals. We also report on the oncoming developments to increase the flexibility of the facility.

The Minerva Beamline at the ALBA synchrotron is a dedicated soft X-ray (1 keV) metrology beamline designed to support the development, testing, and fabrication of the optics for the upcoming NewAthena X-ray space observatory, a mission led by the European Space Agency (ESA). The primary objective of Minerva is the optical characterization, alignment, and assembly of silicon mirror stacks into complete Mirror Modules (MM), which will form the telescope main optics. These stacks are based on Silicon Pore Optics (SPO) technology developed by cosine, a Dutch company. This presentation will provide an overview of the design, capabilities, and metrological performance of the Minerva beamline, emphasizing its suitability for space-grade X-ray optics validation in terms of stability and precision. Recent results from the characterization of MM performed at Minerva will be presented, including the agreement between the modeling of the optical parameters and the data obtained. In addition, ongoing developments towards future implementation of MM assembly process will be discussed.

Insights from previous X-ray missions like Chandra have shown that contamination build-up on cold focal plane detectors is a problem that needs to be mitigated in future orbital missions. These contamination concerns can be addressed with the use of free-standing blocking filters that can be heated to room temperature via the filter support mesh. Using SiC grids, it is possible to manufacture large, high-throughput grids that can be held at room temperature with a lower power consumption than traditional grids. In this presentation, we present large SiC grids with geometries that increase X-ray filter strength, transmittance, and temperature uniformity, with up to 128 mm apertures. This size is suitable for AXIS, newAthena, or a future Lynx style mission. A key part of the research is to understand how the temperature profile of the SiC grids behave when in a radiative cooling environment and determine the power needed to return the grids to room temperature. Here, we describe the planned research to prove this grid technology in flight-like conditions in order to increase technology readiness level.

EP4K is a 4k x 4k, 15-um-pixel, back-illuminated scientific CMOS detector optimized for the Einstein Probe Wide-field X-ray Telescope (EP/WXT). It delivers low read noise, low dark current, low image-lag, high frame-rate readout, and uniform response suitable for soft-X-ray imaging spectroscopy. With pixel-level gain calibration, EP4K can achieve a markedly sharpened spectral performance — ~125 eV FWHM at 4.5 keV. The aluminum-coated implementation integrates effective optical blocking while preserving in-band X-ray throughput and core detector metrics. Radiation testing and long-duration aging also show its stable performances. These results and the inflight performance validate EP4K as a mature/candidate detector for EP/WXT and future soft-X-ray missions.

Recent advances in X-ray astronomy have highlighted the need for more accurate and efficient detector systems in space-based telescopes and laboratory testbeds. This research investigates the application of machine learning algorithms to improve the performance, calibration, and data analysis processes of X-ray detectors used in astronomical instrumentation.The study first introduces the theoretical background of X-ray detection, detector architectures, and conventional data processing techniques. It then presents supervised and unsupervised machine learning methods applied to real and simulated data obtained from X-ray detector systems. The algorithms are optimized for tasks such as noise reduction, energy calibration, and event classification, aiming to enhance detector sensitivity and spectral resolution.Experimental results demonstrate that integrating machine learning into the X-ray data pipeline can significantly improve accuracy and efficiency compared to traditional approaches. The findings suggest that these methods can play a crucial role in future X-ray astronomical missions by enabling more precise measurements and faster data processing, ultimately advancing the capabilities of X-ray astronomical optics.

The first all-sky X-ray survey was performed by the ROSAT X-ray observatory in the 0.1–2.4 keV energy range (Trümper 1982). It was not until almost 30 years later that an all-sky X-ray survey was to be carried out again with the SRG/eROSITA X-ray mission. Between December 2019 and December 2021, four all-sky surveys were completed. The sensitivity of eROSITA at soft energies is not as good as ROSAT's. However, we have previously shown that it is possible to detect white dwarfs in eROSITA data: almost 300 white dwarfs from Gentile-Fusillo et al. (2021) were found in the current cumulative eROSITA all-sky data from the surveys 1–4, which are limited at lower energies to 0.2 keV (Friedrich et al. 2025). Some of already known white dwarfs, however, could only be detected by processing eROSITA data with a lower energy threshold of 0.1 keV instead of 0.2 keV. Simulations are currently underway with a lower energy threshold of 0.1 keV to optimize data processing. It is planned to reprocess the eROSITA data with this lower energy threshold of 0.1 keV to not only increase the number of white dwarfs detected in the X-ray range, but also to obtain more information about other soft sources, such as cataclysmic variables, isolated neutron stars, and AGN.

Upcoming missions will be able to combine X-ray spectral, timing, and polarimetric techniques to study the accretion/ejection processes near black holes, measure black hole mass and spin, and test Einstein’s theory of General Relativity against alternative viable theories in the strong field regime. The recent decade has seen a significant progress in our capabilities to test the nature of astrophysical black holes with X-rays, gravitational waves, and black hole imaging. The currently available constraints are still very limited but they can be improved with the next generation of observational facilities in the foreseeable future. The diversity of techniques, including the spectral, timing and polarimetric studies, will ultimately provide independent checks that can validate the methods and models.

Electromagnetic radiation is scattered by small dust particles in the interstellar medium. Unlike in the visible range, this occurs at small angles in the X-ray range. This offers the unique opportunity to measure both components of extinction, namely scattering and absorption, in a single observation, because X-ray sources behind sufficiently large dust column densities are surrounded by a diffuse halo whose morphology and spectrum contain information about the grain size distribution and composition of the dust, as well as the geometry of the intervening medium. In this review, I will summarize the fundamental physics of X-ray scattering—including the relevant cross sections, angular dependence, and energy scaling—and discuss how observations over the past decades, from ROSAT to eROSITA have contributed to our understanding of the interstellar medium. I will also highlight how scattering halos from time-variable or transient sources have enabled precise distance measurements to dust clouds and X-ray sources.

Since the recurrence times Tc of outbursts in soft X-ray transients (SXTs) are not periodic and their typical length is months, years, or decades, X-ray monitors are needed to detect them and investigate their evolution. Significant values can be obtained even when the different monitors with various energy bands, available for the individual time segments (years or decades), are used (e.g., ASM/RXTE, MAXI/ISS, BAT/Swift). The observations show that changes of Tc between the neighboring (or nearby) outbursts were often much smaller than the length of Tc in a given object. Jumps of Tc only sometimes replaced them. Evolution of Tc in a given SXT shows a complex curve with episodes of increase and decrease. For example, the analysis of the recurrence time Tc of outbursts in Aql X-1, using the method of O-C residuals, revealed that the character of the O-C curves bears a striking similarity to that of dwarf novae observed in the optical band. It means that variations of Tc are large, but generally not chaotic, and long-term trends in the O-C curves can be resolved. The evolution of Tc shows several large jumps. The switches of Tc can occur within just a single epoch. Observing the variety of the X-ray evolution of many dwarf novae is still limited by the low sensitivity of the current X-ray monitors.

Several competing simplified models have been proposed to explain the rapid quasi-periodic variability observed in X-ray radiation emitted by accreting black holes and neutron stars. These models usually only reproduce part of the observed phenomenology and face a number of challenges. In order to address these issues and identify ways to improve the individual models, we adapted the full relativistic ray-tracing code LSD, developed by Bakala et al. (2015, A&A). Based on this, we have developed an advanced, modular code that allows us to study radiation from various configurations of accretion systems. These include accretion disks, tori and inhomogeneous accreted matter, as well as the corona and the possible boundary layer on the surface of an accreting star. Here, we present the results of simulations of the behaviour of such systems, along with analyses of their observable manifestations. To enable comparison with the real variability of X-ray emission observed by space observatories, we also present synthetic data showing how these systems would appear when observed with the existing XRISM and upcoming newATHENA observatory.

The vertical (Lense–Thirring) precession of the innermost accretion flows has been suggested as the cause of a particular type of low-frequency quasi-periodic variability (LF QPOs) observed in accreting neutron stars (NSs). In this context, LF QPOs have been discussed as a sensitive potential indicator of NS rotational properties and their equation of state, since the precession frequency vanishes for a non-rotating star. However, no observational evidence showing a clear trend of increasing QPO frequencies with increasing NS spin across a group of sources was found, which may falsify the model. We examined the expected precession frequencies within the innermost accretion region in detail. Taking the effects of stellar oblateness into account, we found that the precession frequency only increases within a short interval of increasing spin; then it drops and only increases again for even higher spins. We conclude that very different groups of accreting NSs — slow and fast rotators — can display the same precession frequencies. Therefore, the lack of observational evidence for a correlation between QPO frequencies and NS spin does not contradict their precession origin.

Members of the High Energy Astrophysics group at Masaryk University (MUNI) participated in the scientific activities related to the Performance Verification phase of the XRISM satellite as ESA Guest Scientists. They were active members of the target team for the Centaurus Cluster of galaxies and analysed complementary Chandra data, contributing particularly to the studies of the chemical abundances in the cluster core. Members of the HEA group are also currently active in the studies and interpretation of XRISM data from the Perseus Cluster and other systems. In my talk, I will summarise these activities and the exciting new XRISM results on galaxy clusters.

Background: Historical photographic plate archives capture century-scale sky variability and objective-prism spectroscopy, but heterogeneous emulsions, optics, and digitization pipelines complicate quantitative reuse. Gap: Prior surveys cover either plate history or generic ML in astronomy; few synthesize plate-specific calibration challenges with modern ML practice and reproducibility guidance. What this review adds: (i) a unified taxonomy from plate scanning to ML evaluation; (ii) best-practice checklists for calibration and leakage-safe validation; (iii) a practical pipeline and a benchmark wish-list to enable comparable results across archives. Approach: We map digitization and metadata workflows to ML-ready representations (images, catalogs, 1D spectra), summarize modeling options (classical ML, CNNs, self-supervised learning, domain adaptation), and highlight evaluation protocols that respect plate-level correlations and time leakage. Key recommendations: Standardize density→intensity linearization and WCS/zero-point quality control; adopt plate-held-out cross-validation; release machine-readable provenance; and explore self-supervised pretraining with light fine-tuning per observatory. Outlook: With robust calibration and open benchmarks, century-long plate data can power discoveries of rare transients, illuminate long-term stellar evolution, and recover historical AGN variability while serving as a testbed for domain adaptation across instruments and epochs

We develop an end-to-end simulation pipeline to evaluate the detectability of high-frequency quasi-periodic oscillations (HFQPOs) in signals from black hole X-ray binaries with various space observatories. Light curves (LC) from analytic (Karas, 1996) and ray-traced (Bakala et al., 2007, 2015) hotspot models are combined with the global flux of microquasar GRS 1915+105; and photon events with SIXTE (Dauser et al., 2019), using SIMPUT (Schmid et al., 2013), for XRISM (Tashiro, 2022) and the planned new ATHENA (Cruise et al., 2024) are generated. We analyze power density spectra (PDS) of observed LC to recover the fundamental and harmonic frequency peaks across models and signal-to-background ratios. The study benchmarks simulated performance against RXTE and LOFT to validate the capabilities of new missions to observe HFQPOs. We found that WFI detector onboard new ATHENA robustly recovers the HFQPO fundamental and harmonics for the tested setups.

Relativistic accreting stars in low-mass X-ray binaries often exhibit strong quasi-periodic oscillations in their radiation. In our study, we examined the modulation of X-ray radiation from the neutron star boundary layer through the obscuration of an oscillating, thick inner accretion flow (Torok et al., ApJ, 2025). To do this, we adopted the full relativistic ray-tracing code LSD of Bakala et al. (2015, A&A). We found that the investigated mechanism adequately explains the high amplitudes of the observed rapid NS variability. Additionally, it reproduces the differences observed in this variability between neutron star and black hole cases. Here, we briefly discuss these results and present several extensions. These include synthetic data that could be verified or falsified by the newAthena X-ray observatory in the future.

We analysed the impact of individual relativistic effects on the X-ray flux of a neutron star's boundary layer, which is modulated by obscuration from an oscillating, thick inner accretion flow. We compared the results of our fully relativistic ray-tracing simulations with their Newtonian counterparts. To achieve this, we adopted the full relativistic ray-tracing code LSD (Bakala et al., 2015, A&A). We found that for a neutron star with a radius smaller than that of the innermost stable circular orbit (ISCO), the Newtonian limit is insufficient and relativistic ray tracing must be used. However, for less compact stars, the Newtonian approach provides reliable estimates of light curve modulation.

Most models used to fit Fe-Ka lines in neutron star systems assume that X-ray emission comes from the accretion disk alone and neglect the stellar surface. This simplification omits obscuration effects and possible iron line emission from the surface, where shear-heated material cools and spreads. Here, we present a relativistic model that incorporates both components consistently. Using full relativistic ray tracing, we compute photon trajectories from the disk and the neutron star surface. The resulting spectra demonstrate that even a modest surface contribution can significantly alter the observed line shape. Finally, we present synthetic spectra as they would appear when observed using the XRISM and newATHENA observatories.

The AXRO history is related to the history of X–ray astronomy in general and to the history of X-ray optics developments in the Czech Republic (and formerly in Czechoslovakia) in particular. The first Czech X-ray mirror was built already in the years 1969/1970, for a solar telescope within the Eastern Europe/Soviet INTERKOSMOS program, There were also essential efforts devoted to the development of novel technologies for satellite projects which were either canceled or interrupted. The two wasted years of development on the technology of high-quality Ni foils for the Danish SODART telescope (Schnopper, 1990), 1986-1988, can serve as an example. The SOviet-DAnish Roentgen Telescope (SODART) was planned for on board the Spectrum Roentgen Gamma (SRG) satellite equipped with three different instruments devoted to X–ray spectroscopy. Each of the two thin foil telescopes had an 8m focal length, a 60 cm diameter, a 1 deg field-of-view (FOV), a half-power width better than 2 arcmin and ca. 1 700 and 1 200 cm2 collecting area at 2 and 8 keV, respectively. In the last three decades developments of innovative technologies for X-ray optics continued with an emphasis on glass foils and silicon wafers mostly in Multi Foil Optics arrangements and Schmidt Lobster Eye and Kirkpatrick Baez geometries. The late achievements are then related to the AHEAD2020 PROJECT recently finished.

I will give the concluding address for the AXRO conference. The goal of the workshop was to present and to discuss recent and future technologies for X-ray astronomy missions. These missions require the development of most innovative technologies, and we discussee in detail the possibilities, the results obtained so far, and new ideas. It is obvious that the requirements of future large space X-ray astronomy missions are so demanding that they need a truly interdisciplinary approach in a wide international collaboration. These technologies include X-ray optics based on Si wafers, advanced glass forming for precise X-ray optics, but also other possible technologies and alternatives, as well as related advanced metrology, measurements and tests.