Having seen the halo around the Moon, I became aware that I hadn't recognised a solar corona. This is caused by diffraction and not refraction. Since diffraction angle is linked to wavelength, the redder colour is on the outside. There is a great picture here
https://www.atoptics.co.uk/droplets/corona.htm with an idea of what I need to do next time to improve my image. Also here
https://www.weatherscapes.com/album.php?cat=optics&subcat=corona
