Accurate determination of the plate model based on CCD images with different orientations
Accurate determination of the plate model based on CCD images with different orientations
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DOI：
10.1007/s11434-010-0053-2
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发表时间：
2010-03
影响因子：
--
通讯作者：
Q. Peng;Liang-Jen Fan
中科院分区：
文献类型：
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作者：
Q. Peng;Liang-Jen Fan
用云南天文台1米望远镜上新安装的2k×2kCCD在两个不同的方位上拍摄了疏散星团NGC2168的图像。将一颗来自UCAC 2的星星的星表位置与其相应的实测位置进行比较后，发现在小视场（约7 '× 7'）内有明显的畸变。具体地说，每个视场中的星星的标准坐标（x，η）与其对应的测量坐标（x，y）之间的多项式具有高达4阶的有效项。因此，可以导出明亮的UCAC 2星星的位置测量精度，以及在每个方向（60 s的曝光时间和接近天顶）的0.7mas。这一新发现对于CCD图像在其整个视场中提供高度精确的位置非常重要。
The images of the open cluster NGC2168 are taken using the newly-fitted 2k×2kCCD attached to the 1-m telescope at the Yunnan Observatory with two different orientations. After the catalogue position of a star from UCAC2 is compared with its corresponding measured position, a surprising result shows that a small field of view (about 7’×7’) exhibits an obvious distortion. Specifically, the polynomial between the standard coordinate (ξ,η) and its corresponding measured one (x,y) for a star in each field of view has significant terms as high as 4th order. Accordingly, the positional measurement accuracy of a bright UCAC2 star can be derived as well as ˜7 mas in each direction (60 s of exposure time and near the zenith). This new finding would be important for a CCD image to deliver a highly accurate position in its whole field of view.