It is one of the largest nebulas on the sky -- why isn't it better known? Roughly the same angular size as the Andromeda Galaxy, the Great Lacerta Nebula can be found toward the constellation of the Lizard (Lacerta). The emission nebula is difficult to see with wide-field binoculars because it is so faint, but also usually difficult to see with a large telescope because it is so great in angle -- spanning about three degrees. The depth, breadth, waves, and beauty of the nebula -- cataloged as Sharpless 126 (Sh2-126) -- can best be seen and appreciated with a long duration camera exposure (see: APOD -
https://apod.nasa.go.../ap220914.html)
The featured image is one such combined exposure -- in this case 3.5 hours during this past August from perfect Bortle 1 skies at a desolate Greek island. While the hydrogen gas in the Great Lacerta Nebula glows red as it is excited by light from the bright star 10 Lacertae (one of the bright blue stars just above the red-glowing nebula's center), parts of the nebula glow bright orange likely a result of natural light emission combined with some of the following factors:
1. *Mix of Gas Emissions:* Although hydrogen (H-alpha) tends to dominate with its red emissions, other gases, such as sulfur (S II) and nitrogen (N II), can emit light in the orange-red part of the spectrum. These emissions can mix with the hydrogen light, resulting in the orange hues you captured.
2. *Interstellar Dust and Scattering:* Dust within and around the nebula can scatter blue and green light, allowing redder wavelengths (including orange) to dominate. The effect of this scattering could shift parts of the nebula's emission from pure red to orange.
3. *Camera Sensitivity:* The sensitivity of your one-shot color camera's sensors to different wavelengths can influence how colors appear. Some cameras might pick up subtle differences between red and orange in ways that accentuate certain hues. The balance of red, green, and blue channels might shift the appearance of certain nebula regions to look more orange.
Since no filters were used, the orange color you see is a natural feature captured by your camera. It might represent real emissions from sulfur or nitrogen, or the interplay of light scattering and the camera's sensor characteristics. The image reflects what the nebula looks like across the visible spectrum, influenced by the natural color sensitivity of the imaging setup.
The stars and nebula are about 1,200 light years distant.
Link to the image in Astronbin: <a href="https://astrob.in/oxghih/0/">
Link to the image on my website:
https://pbase.com/image/174879469
