Problems in the determination of contours of solar lines near the extreme limb
Abstract
in the first part of the paper the distorting effects of the Earth's atmosphere on the distribution of light at the extreme linib of the Sun are considered. An analytical expression is found which describes the resultant redistribution of light in the focal plane of the telescope; the effects of "seeing" are represented by a Gaussian term, particle scartering and non-specular reflection by the telescope optics are included in a -law term. This redistribution function forms the kernel of the integral equation relating the true and observed intensities at any point. A geometrical idealization reduces the two-dimensional equation to an equation in one dimension. of solving this equation which do not presuppose an analytical form of the true distribution are investigated and it is shown that the solutions must be regarded as discontinuous. in order to apply these methods, observations of the K line of Ca II were made at points within + 10" arc of the limb, on two days. The relevant parameters in the redistribution function were determined from the observations. A numerical application of the solution of the integral equation then gave the true line profiles. The accuracy attainable in the solution is shown to depend rather strongly on the width of the kernel and hence on the atmospheric conditions.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- 1960
- DOI:
- 10.1093/mnras/120.2.106
- Bibcode:
- 1960MNRAS.120..106H