The Sun

 

Sunny days and the sun shows several sunspots and prominences. The images were taken with Ha and CaK filters, different wavelengths.

 

A CaK filter (Calcium K-line filter) is a specialized solar filter for telescopes that isolates light at a specific wavelength of 393.3 nm in the deep violet/near ultraviolet (UV) spectrum. The filter is used in astronomy to observe and photograph the sun, as it makes the lower chromosphere and the border region with the photosphere visible.

 

H-alpha solar filterH-alpha solar filterA H-alpha (Hydrogen-alpha) solar filter is a specialized and advanced optical system that isolates an extremely narrow light wavelength of 656.28 nanometers (nm), which makes it possible to safely observe the sun's chromosphere. Unlike regular white light solar filters, an H-alpha solar filter shows dramatic details such as prominences (gas clouds ejected from the edge), filaments, sunspots and solar flares.

Great sunspots

Several sunspot groups with active areas. Many eruptions have occurred from these areas in the days, some strong, and have now created auroras as far south as +36 New Mexico. Here in Sweden it is far too bright right now for us to be able to see any auroras. Today's images were taken with CaK filter 394 nm which is in the border area between the photosphere, which is visible in white light, and the sun's chromosphere, which is reserved for narrow-band H-alpha filters. In addition to the structures known from white light, such as sunspots, the network of chromospheric flares distributed over the entire solar surface also becomes visible, which precedes the formation of sunspots, as well as supergranulation cells and Ellerman bombs.