Aims: To formulate, implement, and validate a user-independent release of CLEAN for Fourier-based image reconstruction of hard X-rays flaring sources. Methods: CLEAN is an iterative deconvolution method for radio and hard X-ray solar imaging. In a specific step of its pipeline, CLEAN requires the convolution between an idealized version of the instrumental Point Spread Function (PSF), and a map collecting point sources located at positions on the solar disk from where most of the flaring radiation is emitted. This convolution step has highly heuristic motivations and the shape of the idealized PSF, which depends on the user's choice, impacts the shape of the overall reconstruction. Here we propose the use of an interpolation/extrapolation process to avoid this user-dependent step, and to realize a completely unbiased version of CLEAN. Results: Applications to observations recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter show that this unbiased release of CLEAN outperforms the standard version of the algorithm in terms of both automation and reconstruction reliability, with reconstructions whose accuracy is in line with the one offered by other imaging methods developed in the STIX framework. Conclusions: This unbiased version of CLEAN proposes a feasible solution to a well-known open issue concerning CLEAN, i.e., its low degree of automation. Further, this study provided the first application of an interpolation/extrapolation approach to image reconstruction from STIX experimental visibilities.

翻译：目的：构建、实现并验证一种独立于用户操作的CLEAN算法，用于基于傅里叶的硬X射线耀斑源图像重建。方法：CLEAN是一种用于射电和硬X射线太阳成像的迭代解卷积方法。在其处理流程的特定步骤中，CLEAN需要将仪器点扩散函数（PSF）的理想化版本与一张图进行卷积，该图收集了位于太阳盘面上的点源位置，这些位置是大部分耀斑辐射的发射源。这一卷积步骤具有高度启发式的动机，且理想化PSF的形状取决于用户的选择，从而影响整体重建结果的形状。本文提出采用插值/外推过程来避免这一依赖用户的步骤，从而实现完全无偏的CLEAN版本。结果：对太阳轨道器上搭载的X射线成像光谱望远镜（STIX）记录的观测数据的应用表明，这种无偏CLEAN版本在自动化程度和重建可靠性方面均优于标准算法版本，其重建精度与STIX框架内开发的其他成像方法所达到的精度相当。结论：这种无偏CLEAN版本为解决CLEAN算法中一个已知的开放性问题——即其自动化程度较低——提供了一种可行的解决方案。此外，本研究首次将插值/外推方法应用于从STIX实验可见度数据中重建图像。