| Abstract : | The Earth’s atmosphere, due to its inhomogeneous nature, distorts incoming celestial light. This leads to reduced resolution of ground-based telescopes. To minimise the negative effects, Adaptive Optics (AO) systems are used to correct for the wavefront distortions in realtime. However, the field-of-view that can be corrected by using a classical single conjugate AO system is limited to few arc-seconds. This is due to the isoplanatic patch - region of atmosphere over which phase disturbances introduced to the wavefront can be considered to be minimum.
We have used the H-$\alpha$ images of the Sun taken at Merak and the Parametric Search Method (Rengaswamy, Ravindra, and Prabhu (Solar Phys. 294, 5, 2019)) to determine the $r_0$ values by considering different angular regions of the solar image and obtained a plot of angle on the sky versus $r_0$. We have then generated phase screens of these $r_0$ using Kolmogorov model for atmospheric turbulence and decomposed them into Zernike polynomials. Now, the correlation of the Zernike coefficients as a function of angle on the sky can be estimated. We have compared our results with theoretical predications made from analytical equations. This is one way of practically establishing the isoplanatic patch during the daytime. |
