Imaging from STIX visibility amplitudes

Aims: To provide the first demonstration of STIX Fourier-transform X-ray imaging using semi-calibrated (amplitude-only) visibility data acquired during Solar Orbiter's cruise phase. Methods: We use a parametric approach by which amplitudes are fitted means two non-linear optimization methods: fast meta-heuristic technique inspired social behavior, and Bayesian Monte Carlo sampling method, which, although slower, provides better quantification uncertainties. Results: When applied to set solar flare recorded on November 18, 2020 methods very coherent results. The analysis also demonstrates ability reconstruct high time resolution information and, from spectral viewpoint, shows reliability double-source scenario consistent with thermal versus nonthermal interpretation. Conclusions: In this preliminary based only amplitudes, we formulate problem as issue addressed high-performance techniques that both showed sample space in an effective fashion, thus avoiding local minima.