A Preliminary Comparative Study on the Centering Algorithms for CassiniISS NAC Images  

作　　者：T.Liang Q.-F.Zhang G.-M.Liu W.-H.Zhu C.-S.Wang 

机构地区：[1]Department of Computer Science,Jinan University,Guangzhou 510632,China [2]Sino-French Joint Laboratory for Astrometry,Dynamics and Space Science,Jinan University,Guangzhou 510632,China [3]School of Computer Science,Guangdong University of Education,Guangzhou 510303,China

出　　处：《Research in Astronomy and Astrophysics》2024年第10期58-65,共8页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.12373073,U2031104,No.12173015);Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011340)。

摘　　要：Obtaining high precision is an important consideration for astrometric studies using images from the Narrow Angle Camera(NAC)of the Cassini Imaging Science Subsystem(ISS).Selecting the best centering algorithm is key to enhancing astrometric accuracy.In this study,we compared the accuracy of five centering algorithms:Gaussian fitting,the modified moments method,and three point-spread function(PSF)fitting methods(effective PSF(ePSF),PSFEx,and extended PSF(x PSF)from the Cassini Imaging Central Laboratory for Operations(CICLOPS)).We assessed these algorithms using 70 ISS NAC star field images taken with CL1 and CL2 filters across different stellar magnitudes.The ePSF method consistently demonstrated the highest accuracy,achieving precision below 0.03 pixels for stars of magnitude 8-9.Compared to the previously considered best,the modified moments method,the e PSF method improved overall accuracy by about 10%and 21%in the sample and line directions,respectively.Surprisingly,the xPSF model provided by CICLOPS had lower precision than the ePSF.Conversely,the ePSF exhibits an improvement in measurement precision of 23%and 17%in the sample and line directions,respectively,over the xPSF.This discrepancy might be attributed to the xPSF focusing on photometry rather than astrometry.These findings highlight the necessity of constructing PSF models specifically tailored for astrometric purposes in NAC images and provide guidance for enhancing astrometric measurements using these ISS NAC images.

关 键 词：methods:analytical techniques:image processing stars:imaging ASTROMETRY 

分 类 号：P12[天文地球—天体测量] V447.1[天文地球—天文学]