IC434, The Horsehead Nebula Region

Click image for larger version.

In the winter when Orion is high in the southern sky look for the three stars that make up his belt.  The one on your left, toward the east is called Alnitak and that's the very bright star, center left in this image.  Just south of Alnitak (to the right in this image) is B33, the Horsehead Nebula and just east (down in the image) is NGC 2024, the Flame Nebula.  It's easy to see why these nebulae have their names.

The overall region of emission nebulosity, the clouds that are reddish in color, is designated as IC434 in the Index catalog and is only a small part of the  Orion Molecular Cloud Complex which spans pretty much the entire region of the Orion constellation.  There are also a number of reflection nebulae in the region including NGC 2023 just below and left of the horse's head and IC 432 left of Alnitak.  B33 is known as a dark nebula.  Dark nebulae are so called because they are denser clouds of gas and dust that block our view of objects behind them; in this case the emission nebula itself but often star clouds in the Milky Way creating what appears to be a hole in the galaxy.

The area can be observed visually with a moderate aperture telescope greater than perhaps 10".  The Flame Nebula is quite easy to discern as a hazy patch of light just outside of the glare of Alnitak.  It would be easy to overlook it so near such a bright star except that the dark dust lanes in the nebula standout in comparatively stark relief.

The Horsehead is much more difficult to see and normally requires a Hydrogen Beta filter to see well in such telescopes.  I have been able to just pick it out in telescopes of 17" or larger and only when the field of view does not include Alnitak. 

Date:  1/2013

Location:  4Domes Observatory

Telescope:  TMB130SS @ f/5.25

Mount:  AP-1200

Camera:  SBIG STL-6303E

Acquisition and Guiding:  CCD Autopilot controlling Maxim DL