SOLAR: 18mm Blocking Filter Module (for viewing Ca-K) in a 2-inch Star diagonal with T2 connection from Lunt Solar Systems.
Calcium K Module
Calcium K (Ca-K) telescopes and filters are used to study the wavelength of 393.4 nm. This emission line is one of two that are produced by Calcium just at the edge of the visible spectrum. Comparatively, this is in a layer that is slightly lower and cooler than the layer viewed in Hydrogen-alpha. The emission line displays areas of super granulation cells that are brightest and strongest in areas of high magnetic fields, such as sunspot activity and active regions. Having the ability to study the Calcium K and the Hydrogen-alpha line provides important insights into the structure, strength, and depth of these active regions. This is easily accomplished in seconds by switching from your H-alpha filter to your Calcium K modules.
The Calcium K modules line is centered at 393.4 nm. This wavelength is considered to be slightly outside the visible spectrum on the UV side. While most people can visually see the violet color of the wavelength, many cannot resolve the contrast due to yellowing of the cornea. People who have had cataract surgery are often able to see considerable detail. But, it is for these reasons that the Ca-K line is typically studied via the use of cameras, which are able to provide stunning details.
Internal narrowband filters allow for a <2.4 Angstrom bandpass. This is primarily an imaging system due to the difficulty of many to visually see everything that CaK has to offer.
Image Note: Filter shown is the B600 size of the LS-CaKMD for demonstration of similarity.