DayStar is proud to offer Calcium H ( 3969Å ) and two Calcium K-line (3933.7Å ) filtering systems. Traditionally, university research has employed the Calcium K line for studies of Calcium on the Sun. These studies have been instrumental in determining depth of the solar atmosphere. Calcium offers TWO strong absorption lines at 393.3nm and at 396.9nm, known as the K and H lines. Researchers have previously avoided the H line for academic research, as it is very close to the Hydrogen Epsilon line. For purposes of clarity in isolating Calcium, and because imaging sensors offer similar sensitivity to the K as the H lines of Calcium, the K has to date been the target of choice in Calcium filters.
However, as the visual spectrum ends at approximately 400nm, the further we venture below this wavelength, the more difficult it is for observers to visually see the image. The H line for visual observations, is much closer to the visual spectrum and easier to see in high contrast violet color. Some observatories have been imaging in Ca II H line, such as the Dutch Open Telescope with outstanding results.
DayStar Calcium K-line Quantum Filters 2.0Å suitable for academic purposes - Ideal application: with CCD photography or indoor visual viewing environment
2.0Å PE Quantum Solar Filter, Calcium K line. For use with refractors, SCTs, Maksutovs. Includes front and rear plates, power supply, instructions, and hard case. Requires UV/IR cut filter, plus Powermate barlow or stop down mask to reach F/13-F/35 focal ratio for best performance (sold separately).