低成本全天相机的自动天体测量校准
Automatic astrometric calibration of low-cost all-sky cameras
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中文总结 AI 辅助
提出一种结合鱼眼模型、精确旋转和自动恒星匹配的开源流程，实现低成本全天相机的自动天体测量校准，在测试数据上达到亚像素精度，并支持单帧初始化与校准复用。
中文摘要 AI 辅助
全天相机支持天气监测、业余天文学、火流星和空间碎片探测以及光污染测量。这些应用需要可靠的天体测量校准，尽管相机对准不完美且观测条件多变。我们提出了一种开源流程，结合了紧凑的鱼眼模型、考虑相机倾斜的精确旋转以及自动恒星匹配。在给定观测站点坐标和观测时间的情况下，它可以从单帧图像初始化校准。我们在使用Raspberry Pi相机和1.55毫米镜头获得的九帧无云、无月亮的帧上评估了该流程。依次在八帧上拟合并在第九帧上评估，在4172次匹配中给出了0.70像素的中值残差（95%区间为0.64-0.80像素），通过两个可选的偏心参数可将其降低到0.60像素。所有九次单帧校准均通过质量标准，并预测其他帧上的位置，中值残差为0.78像素，每次校准约需六秒。我们还将晴朗天空校准应用于73帧具有不同月球照明或云层覆盖的帧，在月光帧上对接受的匹配获得了可比较的残差（0.62像素）。这些结果支持在相机几何结构保持不变且足够多的恒星可见以进行可靠匹配时重复使用校准。该流程可作为Python包ascal使用。
英文摘要
All-sky cameras support weather monitoring, amateur astronomy, fireball and space-debris detection, and measurements of light pollution. These applications require reliable astrometric calibration despite imperfect camera alignment and variable observing conditions. We present an open-source procedure that combines a compact fisheye model, an exact rotation to account for camera tilt, and automatic star matching. It can initialise a calibration from a single frame given the observing site coordinates and observation time. We evaluate the procedure on nine cloud-free, moonless frames, obtained with a Raspberry Pi camera and a 1.55 mm lens. Fitting on eight frames and evaluating on the ninth in turn gives a median residual of 0.70 px (95\% interval 0.64-0.80 px) across 4172 matches, reduced to 0.60 px by two optional decentering parameters. All nine single-frame calibrations pass the quality criteria and predict positions on other frames with a median residual of 0.78 px, taking about six seconds per calibration. We also apply the clear-sky calibration to 73 frames with varying lunar illumination or cloud cover, obtaining comparable residuals for accepted matches on moonlit frames (0.62 px). These results support reusing a calibration while the camera geometry remains unchanged and enough stars remain visible for reliable matching. The procedure is available as the Python package ascal.
发表机构
- Universidad Internacional de La Rioja (UNIR)（西班牙国际大学）
- Departamento de Física, Universidad de Oviedo（奥维耶多大学物理系）
- Allande Stars（阿兰德之星）
机构由 AI 辅助整理，请以论文原文为准。
