Design and Analysis of a Comprehensive Pointing Model for the Altazimuth Telescope

Abstract To further improve the pointing accuracy of altazimuth telescopes, this study takes the NAOC 2.5 m telescope as the research object and develops a comprehensive pointing model. The paper first analyzes the causes of errors and accordingly constructs three core models: the basic parametric model, the spherical harmonic model, and the polynomial regression model. Among them, the basic parametric model aims to fit error terms with clear physical meanings, but its correction capability is limited and cannot fully cover all influencing factors. To address this limitation, a spherical harmonic model is introduced. This model demonstrates excellent performance in handling higher-order error terms and can accurately fit errors across the celestial sphere. Additionally, a polynomial regression model is designed to improve the fitting capability and prediction accuracy for nonlinear errors by flexibly adjusting the polynomial order. The resulting comprehensive pointing model combines the advantages of these three models, enabling more precise and complete correction of pointing errors while balancing computational complexity and accuracy by adjusting the fitting weight of each model. Experimental verification shows that the telescope’s pointing accuracy is improved from 17 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 805 to 3 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 1029, meeting the requirements for high-precision astronomical observations.