2.4米望远镜天体测量试验

An Astrometric Experiments on the 2.4m Telescope of the Yunnan Observatory

利用文[1]提出的方法,求解出云南天文台丽江观测站2.4 m望远镜CCD图像中的几何扭曲模型。将求解的模型应用到同期观测所得Phoebe(土卫九)的116幅CCD图像表明:扣除视场几何扭曲的影响后,该卫星定位精度明显提高。土卫九天体测量精度在每个方向约为0."02～0."03。

Geometric distortions （GDs） are important in high-precision astrometry. In this paper, we report some experiments to analyze the effect of GD on the positional measurement of the Phoebe （the ninth satellite of the Saturn）. The approach recently proposed by us in Reference [ 1 ] has been used to process our observed data to correct for the GDs. In total, 212 frames of CCD images were taken by the YFOSC （Yunnan Faint Object Spectrograph and Camera） attached to the 2.4m telescope of the Yunnan Observatory during February 18-19, 2012. Specifically, 96 of these frames are for the open cluster NGC 2324 and the other 116 are for the Phoebe. Our data reduction shows that the precision of the positional measurement of the Phoebe is significantly improved with GDs corrected. The mean GD residuals （observed minus computed） are 0.23 arcsec and -0.17 aresec in right ascension and declination, respectively, with the standard deviation in each direction about 0.03 arcsec.