The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures.
The Crescent Nebula is a rather small object located about 2 degrees Southwest of Sadr. While considered bright by astronomical imaging standards, visually it is relatively faint. For most telescopes it requires a UHC or OIII filter to see. Under favorable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. With higher magnification, it has been reported to have a resemblance to a Euro sign shape leading to a nickname the “Euro Sign Nebula.”
This is the second image I have taken with the help of my new processing buddy Lucky, AKA ChatGPT. The help I have received from AI has been amazing. From what to image, what settings, exposure, gain and integration to how to process in Pixinsight has been like having a NASA professional guiding me step by step.
Object Designations: NGC6888, Caldwell 27, Sharpless 105
Also known as: Crescent Nebula
Constellation: Cygnus
Object Type: Emission Nebula
Distance: 5,000 light-years away
Magnitude: 7.4
Discovery: William Herschel
Telescope: Apertura CarbonStar 200 Imaging Newtonian 800mm / F4
Camera: ZWO ASI2600 MC Pro – Antlia Triband RGB Ultra II Filter
Mount: Celestron AVX – With CPWI Software
Guiding: Apertura 32mm Guide Scope with a ZWO ASI120MM Camera and PHD2
SharpCap Imaging Software
Processing Software
AstroSharp Ltd SharpCap
Pleiades Astrophoto PixInsight
GraXpert
Russell Croman Astrophotography BlurXTerminator
Russell Croman Astrophotography NoiseXTerminator
Russell Croman Astrophotography StarXTerminator
Various scripts
ChatGPT’s guidance to overcome my color-blind eyes.
This final image is:
265 –300 second subs at 100 gain, Antlia Triband RGB Ultra II Filter
July 2, July 3, July 12, July 13, July 14 and July 15, 2026
White Bal (B) = 46
White Bal (R )= 67
Brightness = 50
Camera Temperature = -10
LastPlateSolveData=Plate solve result was RA=20:14:12.8,Dec=+38:37:39 with mount at RA=20:14:13.0,Dec=+38:37:39, FOV 1.759×1.176 degrees, up is 90.08 degrees East of North
