Astrophotography

Sun

The sun in H-alfa light

daystar-telescoop H-alpha (Ha) is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level. A hydrogen-alpha filter is an optical filter designed to transmit a narrow bandwidth of light generally centered on the H-alpha wavelength. They are characterized by a bandpass width that measures the width of the wavelength band that is transmitted. These filters are manufactured by multiple (~50) layers of vacuum-deposited layers. These layers are selected to produce interference effects that filter out any wavelengths except at the requisite band.

Alternatively, an etalon may be used as the narrow band filter (in conjunction with a “blocking filter” or energy rejection filter) to pass only a narrow (<0.1 nm) range of wavelengths of light centred around the H-Alpha emission line. The physics of the etalon and the dichroic interference filters are essentially the same (relying on constructive/destructive interference of light reflecting between surfaces), but the implementation is different (an interference filter relies on the interference of internal reflections). Due to the high velocities sometimes associated with features visible in H-alpha light (such as fast moving prominences and ejections), solar h-alpha etalons are often able to be tuned (by tilting or changing the temperature) to cope with the associated Doppler effect.

In 1802, the English chemist William Hyde Wollaston was the first person to note the appearance of a number of dark features in the solar spectrum. In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the wavelength of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters. Modern observations of sunlight can detect many thousands of lines.

In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer (1787–1826) . The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun. The Fraunhofer C line correspond to the alpha line (656.28 nm) of the Balmer series of emission lines of the hydrogen atom.

Images of the sun with a 0.6A Daystarfilter, 8cm ERF and 10inch LX200GPS

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If you are interested in solar exploration I have an give away for you. I give you Solarobserver issue-1 (100 pages) for free to download. By Lack of time of the editor, the website SolarObserver has gone down. That’s why I want to keep this ebook for free.

solarobserver1

Download: SolarObserver1

Hoover over and click on an catagory album picture to see the whole gallery. Click again for bigger pictures and slideshow.

H-alfa images (b/w – false color)

These false-color images are made to split one b/w image into a RGB in paintshop and proces the RGB-chanals different and combine again.

H-alfa RGB images

R=Setting-8 / G=Averang R&B / B=Setting-2

Make two different b/w images with different settings (2 & 8) with the Daystar 0.6A ATM H-alfa filter.

Tune this two different images and make a Red chanel of the setting-8 and setting-2 into a blue chanel. Average the Red and Blue chanel and this is the green chanel. Combine this to one RGB-image and proces this further with paintshop.