Seeing conditions

In order to investigate the relationship between the FWHM of the seeing disk for observations with the performance of the Lucky Exposures method, all the observations in Tables 3.2 and 3.3 were analysed using the Lucky Exposures approach. The best $1\%$ of exposures were selected in each case, and the Strehl ratio for the image obtained in this way is plotted against the FWHM of the seeing disk in Figure 3.37. There is a clear relationship between these two parameters, indicating (as expected) that the highest image quality is obtained under conditions where the conventional seeing disk is small. The scatter in the results may be due to the strong dependence of seeing FWHM on the low-order tip-tilt components in the wavefront perturbations, which have insignificant effect on the Lucky Exposures image quality. The regression coefficient for the fitted line is $r^{2}=0.44$.

Figure 3.37: Strehl ratio for the Lucky Exposures image generated using best $1\%$ of exposures plotted against the seeing FWHM for each of the runs.