NVST成像成谱观测数据处理关键问题研究

The imaging spectroscopy observation of the Solar can not only obtain the monochromatic images with high spatial resolution, but also obtain the spectral information of each spatial position in the observation region through the multi-band scanning monochromatic images, which becomes one of the most important methods of solar observation. The one meter new vacuum solar telescope (NVST) has observed a large amount of imaging spectral data at present，It is found that is difficult to accurately obtain the spectral profiles of observation area from the multi-band high-spatial monochrome images. As a result, most of the current researches are only used line center or 2-3 off-band images, which seriously reduces the applications value of imaging spectral data and the scientific output of the NVST. The project mainly studies the reasons of the distortion for the spectral profiles extracted from spectral imaging data, and will carefully process the imaging spectral data from three aspects, including fine registration between monochrome images with different off-bands, calibration of spectral profile for each spatial point of observed area and fitting of the different spectral profiles. All the problems existing in the NVST imaging spectral data will be analyzed in detail to put forward the corresponding treatment methods. Finally, the accurate spectral information of each spatial point will be obtained, so that the scientists can further study the physical characteristics of solar activities.

太阳的成像成谱观测不仅可以得到高空间分辨率的单色像，而且能够通过多波段扫描的单色像获取观测区域各空间位置的光谱信息，成为太阳观测的最主要方式之一。一米新真空太阳望远镜(NVST)目前观测了大量的成像成谱数据，研究发现尽管有了多波段的高空间单色像，依然很难准确地获取空间各点的光谱轮廓，使得目前的研究成果大多集中于采用线心或者仅2-3个偏带的数据，这严重降低了成像成谱数据的利用价值和望远镜的科学产出。本项目主要研究引起NVST成像成谱数据谱线轮廓失真的原因，从三个方面对成像成谱数据进行精细地处理，包括偏带单色像之间的精细配准、各空间点谱线轮廓的强度定标以及对不同轮廓曲线的拟合，详细分析其中存在的问题并提出相应的处理方法，最终获得各空间点准确的谱线信息，以便科学家们进一步研究太阳活动的物理特性。

NVST多波段成像成谱观测的二维图像各空间点的光谱轮廓存在严重失真，通过研究发现主要是由于大气湍流造成的图像晃动、天气变化引起的强度起伏以及望远镜仪器在不同扫描波段的不均匀性响应所造成。本项目从三个方面对NVST成像成谱数据进行详细的处理：首先，提出了一种基于光流场的对齐方法，实现了NVST成像成谱数据的高精度对齐；其次，通过设计实验得到了仪器在不同波长点的不均匀性响应曲线，最后对成像成谱数据加以矫正得到观测区域各点可信的光谱轮廓和基本的物理参量。NVST成像成谱数据经过以上方法的处理最终生成一个标准的数据产品，方便太阳物理学家从中获取太阳大气更多的物理特性，从而实现了NVST成像成谱观测的真正意义，有助于推动NVST的科学产出。