抖动策略与点源Photometry
Dithering Strategies and Point-Source Photometry
摘要：
点源测光的精度取决于点扩散函数、探测器像素化和观测策略。PSF和像素响应描述源的空间模糊，像素尺度描述单次曝光的空间采样，并且观察策略确定具有指向偏移的抖动曝光的集合，从该指向偏移推断源通量。在宽视场成像勘测中，感兴趣的源随机分布在视场内，因此随机地集中在像素内。一个给定的硬件配置和观测策略，因此有一个分布的光度不确定性的固定通量的来源，落在外地。在这篇文章中，我们探讨了不同的PSF，像素尺度和抖动模式的光度和位置精度的集合行为。我们发现，在通量确定的平均不确定性略有依赖于抖动策略，而位置确定可以强烈依赖于抖动。对于像素比PSF大得多的情况，不确定性分布可以是非高斯的，均方根值对抖动策略特别敏感。我们还发现，对于这些配置与大像素，点抖动的分数像素量并不总是给最小的平均不确定性，这是在对比图像重建的分数抖动是最佳的。当支持分数像素抖动时，需要比$\sim 0.15$像素宽度更好的指向精度，以保持优于随机抖动的一半优势。
英文摘要：
The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes the spatial sampling of a single exposure, and the observing strategy determines the set of dithered exposures with pointing offsets from which the source flux is inferred. In a wide-field imaging survey, sources of interest are randomly distributed within the field of view and hence are centered randomly within a pixel. A given hardware configuration and observing strategy therefore have a distribution of photometric uncertainty for sources of fixed flux that fall in the field. In this article we explore the ensemble behavior of photometric and position accuracies for different PSFs, pixel scales, and dithering patterns. We find that the average uncertainty in the flux determination depends slightly on dither strategy, whereas the position determination can be strongly dependent on the dithering. For cases with pixels much larger than the PSF, the uncertainty distributions can be non-Gaussian, with rms values that are particularly sensitive to the dither strategy. We also find that for these configurations with large pixels, pointings dithered by a fractional pixel amount do not always give minimal average uncertainties; this is in contrast to image reconstruction for which fractional dithers are optimal. When fractional pixel dithering is favored, a pointing accuracy of better than $\sim 0.15$ pixel width is required to maintain half the advantage over random dithers.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
