The Sun

ASI2600MM Pro, 200x1mSec Green, Solar Continuum Filter

NEVER point your telescope without appropriate filters towards the sun!

In astronomical terms our star, the sun, is classified as a yellow dwarf of spectral call G2 and would be, when spotted from another location in the milky way, tiny and unremarkable. Observing the sun at higher magnifications from earth is still quite interesting and fun.

Most simple to observe are the sun spots, which change shape and their impressive size across days. For comparison I placed a picture of earth at the bottom left (of course we are not at that spot in reality!). In this image the sun has a diameter of 2120 pixels, which should be 109 times the diameter of earth so the earth-dot has a diameter of 19.5 pixels. The large sunspot has a length of about 70 pixels and could be spotted without a telescope, just using a proper solar filter.

If you already own a telescope, you may simply attach a solar filter at the opening, like the Baader Solar Kontinuum foil. After covering or, even better, removing a mounted guidescope you may point the telescope towards the sun. For proper alignment just observe the shadow of your telescope and adjust for the smallest size. The mount should be aligned good enough to track the sun for a while.

Since observations of the sun typically take place during daytime, turbulences in the atmosphere may be an issue. Luckily the sun is quite bright and allows  quite short exposure times. For this image I captured 200 frames with an exposure time of 1mSec only.

Using the mono camera I tried all filters and green, for some reason, provided the best contrast. In any case it may be useful to also capture narrowband (H-Alpha). With some luck and a strong stretch you may also spot some prominences at the edge.

Stacking and correcting the frames for atmospheric distortions was done in Autostakkert, the tool of choice for observations within the solar system.

Thanks to David Nimmervoll for that hint, he captured the sun some houres earlier on that day: