Taken with the 100mm frac at f5 with homebrew CaK filter and DMK31. This active region was undesignated at the time the image was took (s2377), however now is designated AR11732.
Images of the Sun, our local star, at a range of wavelengths with specialist solar telescopes. Imaging tutorials, solar bits and pieces for sale, talks and outreach with the Charlie Bates Solar Astronomy Project CBSAP.