## 4 Model Optimization Based on Stepwise Regression
### Experiment Results  
Figure 12 shows the results of the full parameter model (FPM) corrected for pointing errors. It is clear that the model works in a limited time, and the correction for azimuth and elevation in the third test is not effective. In contrast, the correction of the optimized parameter model (OPM) works as expected, as displayed in Figure 13, and the maximum residuals are less than 50 arc seconds in all three tests. Here are the details. The corrected azimuth (RMS) is 14.07\({}^{\prime\prime}\), 12.71\({}^{\prime\prime}\), and 28.93\({}^{\prime\prime}\), and the pointing accuracy is improved accordingly, i.e., 90.81%, 92.23%, and 78.79%. Similarly, The corrected elevation (RMS) is 12.94\({}^{\prime\prime}\)  
Figure 11: Original pointing error of the EOT (**a**) in azimuth and (**b**) in elevation. 12.73\({}^{\prime\prime}\), and 28.30\({}^{\prime\prime}\), and the accuracy is improved accordingly, i.e., 98.41%, 98.37%, and 96.41%. As seen in Figure 14, the results of the mount model are similar to those of the optimized parameter model. However, the partial residuals of azimuth fluctuate widely in all three tests. Table 1 compares the RMS and maximum values of pointing errors corrected by the three models. Note that the results of azimuth and elevation are similar in tendency between the three experiments. In contrast, the residual curves of the azimuth and elevation are completely different in each test. What stands out in the graphs above is that there is a  
Figure 14: Residual errors of MM (**a**) in azimuth and (**b**) in elevation. Figure 12: Residual errors of FPM (**a**) in azimuth and (**b**) in elevation. Figure 13: Residual errors of OPM (**a**) in azimuth and (**b**) in elevation. marked and steady trend between the revised elevation and the real azimuth of the target in the geographic coordinate, decreasing and then rising in all three trials. Figure 15: Residuals of FPM, OPM, and MM (**a**) in azimuth and (**b**) in elevation. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Pointing Model**} & **Experiment** & \multicolumn{2}{c}{**Azimuth**} & \multicolumn{2}{c}{**Elevation**} \\ \cline{3-5}  & **RMS** & **Maximum** & **RMS** & **Maximum** \\ \hline \multirow{3}{*}{FPM} & Test 1 & 19.67\({}^{\prime\prime}\) & 52.32\({}^{\prime\prime}\) & 12.10\({}^{\prime\prime}\) & 27.47\({}^{\prime\prime}\) \\  & Test 2 & 17.74\({}^{\prime\prime}\) & 28.21\({}^{\prime\prime}\) & 10.12\({}^{\prime\prime}\) & 19.64\({}^{\prime\prime}\) \\  & Test 3 & 62.18\({}^{\prime\prime}\) & 128.95\({}^{\prime\prime}\) & 79.49\({}^{\prime\prime}\) & 128.15\({}^{\prime\prime}\) \\ \hline \multirow{3}{*}{OPM} & Test 1 & 14.07\({}^{\prime\prime}\) & 30.59\({}^{\prime\prime}\) & 12.94\({}^{\prime\prime}\) & 20.02\({}^{\prime\prime}\) \\  & Test 2 & 12.71\({}^{\prime\prime}\) & 23.02\({}^{\prime\prime}\) & 12.73\({}^{\prime\prime}\) & 16.73\({}^{\prime\prime}\) \\  & Test 3 & 28.93\({}^{\prime\prime}\) & 42.08\({}^{\prime\prime}\) & 28.30\({}^{\prime\prime}\) & 40.42\({}^{\prime\prime}\) \\ \hline \multirow{3}{*}{MM} & Test 1 & 38.43\({}^{\prime\prime}\) & 81.77\({}^{\prime\prime}\) & 12.45\({}^{\prime\prime}\) & 18.23\({}^{\prime\prime}\) \\  & Test 2 & 30.18\({}^{\prime\prime}\) & 91.25\({}^{\prime\prime}\) & 11.89\({}^{\prime\prime}\) & 17.50\({}^{\prime\prime}\) \\ \cline{1-1}  & Test 3 & 43.09\({}^{\prime\prime}\) & 106.14\({}^{\prime\prime}\) & 28.31\({}^{\prime\prime}\) & 40.15\({}^{\prime\prime}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Pointing precision of the EOT after correction. prediction accuracy over the range of independent variables when the model contains more relevant parameters. Secondly, although the optimized parameter model is based on kinematic analysis, the errors contained in the parameters of the model are difficult to separate, leading to reduced reliability in the identification of relevant physical parameters. This is an important issue for future research.