A Shadow in the Glow of Orion
LDN 1622 is a dark molecular cloud that stands out because it is positioned in front of the faint, glowing red emission gas of the Orion Molecular Cloud Complex. The 'Boogeyman' appears as a dark, irregular shape with 'arms' that seem to be stretching toward the stars. Unlike many dark nebulae that are entirely opaque, the edges of LDN 1622 are slightly illuminated by the backlighting of the surrounding H-alpha gas, giving it a ghostly, three-dimensional rim-light effect.
Imaging Challenges
- • Subtle Contrast: The difference between the dark 'body' and the dark background is very slight. High-quality flat frames are mandatory to avoid vignetting being mistaken for nebulosity.
- • Mixed Signal: While it is a dark nebula target, the background is H-alpha. Using a dual-band filter can help the background pop, but you need broadband for the stars and the dust texture.
- • Faint Background: The red glow behind the Boogeyman is much fainter than M42 or the Horsehead, requiring a fast scope and long integration.
LDN 1622 is actually much closer to us than the bright Orion Nebula (M42), which sits about 1,300 light-years away.