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 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.
| Object | NGC6888 Crescent Nebula |
| Constellation: | Cygnus |
| Position: | RA 20h 12m 06.6s / Dec 038° 21' 18'' |
| Apparent Size: | 18 x 12 arcmins |
| Apparent Magnitude: | 7.4 |
| Distance in light years: | 5000 ly |
| Photo Data | |
| Date: | 31 May 2025 - 29 Jun 2025 |
| Location: | Observatory Italy |
| Telescope: | ASA N10 250mm, 3.6/900mm |
| Camera: | Player One Mono IMX571, 23,5 x 15,7mm, 6252*4176 px, 3.76μm, Bin-1, @ T sensor = -10°C |
| Field of View: | arcmins |
| Pixel Scale/Resolution: | arcsec/px |
| Expose frames/times: | R 12x300s, G 12x300s, B 12x300s, H 66x300s, O 86x300s |
| Total expose: | 18h 43min |
| Filter: | Red, Green, Blue, Ha, SII, OIII |
| Mount: | |
| Software: | Siril 1.4, Photoshop CC |
| Remarks: |
© Photos and photo data by Peter Cerveny
© Object description/intro text fully or partially by Wikipedia,
which is released under the Creative Commons Attribution-ShareAlike 4.0 International License