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.

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.

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.