I was shocked when I first looked at the data—a reaction perfectly suited to this target. The Crescent Nebula's striking structure is shaped by expanding shock waves. This began when the Wolf-Rayet star (WR 136) at the center of the emission nebula, while still in its red giant phase, ejected stellar wind that is now colliding with a much more energetic wind from WR 136. These winds create shock waves that travel both inward and outward, leading to strong emissions from hydrogen and oxygen atoms.
For the first time, I used narrowband filters with my mono astro camera to extract the famous H-alpha emission line from the Balmer series (deep red at 656nm) and the OIII emission (between blue and green at 500nm) - both very common in many deep sky objects. It's standard practice to map the hydrogen emission to the red channel in a traditional RGB image, and the oxygen emission to both the green and blue channels. To complete the image, I added an hour of broadband data to preserve the natural star colors, which can be lost with narrowband filters.
Swipe for a starless version, a more detailed view of NGC 6888, the two mono channels, and a short video blinking through the two channels.
📸 Camera: TS-Optics ToupTek MONO Astrokamera 2600MP G2
🔭 Telescope: Sony FE 200-600 @ 600mm F/6.3
⚙️ Mount: ZWO AM5
🎛️ Filter: Astronomik 6nm HII, Astronomik 6nm OIII, Astronomik Deep Sky RGB
🕒 Exposure: 64x5min HII, 64x5min OIII, 20x1min RGB each (11h 40min total, Bortle 4)
🖥️ Captured with: N.I.N.A; Processed with: PixInsight
The Crescent Nebula
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