Accurate determination of the plate model based on CCD images with different orientations |
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Authors: | " target="_blank">QingYu Peng " target="_blank">LiangYan Fan |
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Institution: | 1 Joint Laboratory for Astrometry, Dynamics and Space Science, Jinan University, Guangzhou 510632, China;
2 Department of Computer Science, Jinan University, Guangzhou 510632, China;
3 Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou 510632, China;
4 Joint Laboratory for Optical Astronomy, Chinese Academy of Sciences, Kunming 650011, China |
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Abstract: | The images of the open cluster NGC2168 are taken using the newly-fitted 2k×2k CCD 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 (ζ,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. |
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Keywords: | CCD imaging field distortion positional measurement image analysis |
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