Saturday, June 11, 2016

Some nebulosities in Orion

Orion is one of the most spectacular parts of the sky with enormous, extended nebulas, including the brightest nebula in the northern sky. The aptly named Great nebula in Orion, often known as the Orion nebula, but we will leave that for another time and focus on two other bright and well-known nebulae.
To set the scene we start with a wide field image from a true dark-sky site at 4000m in northern India. It is only a single frame with about 30s exposure. But there is so little light pollution that it is actually hard to pick out the constellations among all the stars.

Anyway, here are the major stars in Orion. As we see they have mostly old arabic names, which is where most historical knowledge of the stars come from. Admittedly, from astrology, but at least they tried.

Now we will turn our attention to two of the nebulae to have a closer look. The Flame nebula, NGC2024, and the very well-known Horsehead nebula IC434.

First we switch from an 11.5 mm aperture f2 camera lens to a proper telescope. In this case a 106 mm f5 Takahashi FSQ ED at iTelescope's observatory at Siding Spring Observatory, Australia. It is located just by the 4-meter Anglo-Australian Telescope. It gives a nice view that includes both nebulae.

Then, we can switch to the 700mm BCL telescope, named for Dame Jocelyn Bell Burnell, Annie Jump Cannon and Henrietta Swan Leavitt, which is a beast among amateur equipment. This gives us a real close-up view of the Horse Head Nebula, which is where we leave off for today.

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