NGC 6888

The Crescent Nebula also known as NGC 6888, 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 to 400.000 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.

It is a rather faint object located about 2 degrees SW of Sadr. 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. Larger telescopes (20 cm or more) reveal the crescent or a € sign shape which makes some to call it the "Euro sign nebula".

Acquiring and processing details

It's my first capture of the NGC 6888, the Crescent Nebula in Cygnus. The focus wasn't optimal yet, I'm still trying to focus manual on this setup, a ZWO EAF is on it's way. The bright stars in the corners have a blueish glow in one direction and seem to be elongated, maybe still a small backfocus issue in combination with bad focus? In total 2.42 hrs of H-Alpha data combined with only 0.42 hrs of RGB. Taken with my newly (March 2021) bought TS61EDPH-II and ASI1600MM-cool. The calibration and integration was done in Astro Pixel Processor and the processing in PixInsight together with Affinity Photo.

  • Date: April 24 - 2021
  • Integration Time: 2.82 hrs
  • Telescope: TS61EDPH-II at f4.5
  • Mount: Skywatcher EQ6-Synscan Go-To
  • Camera: ZWO ASI1600MM-Cool
  • Filters: Ha 29x300", R 19*30", G 17*30", B 17*30"

H-alpha version.

Hubble Pallet SHO processed version.

Acquiring and processing details

This image of the NGC 6888, the Crescent Nebula in Cygnus is a process of four consecutive nights in the late spring of 2021. The window of opportunity was only from midnight to about 04:00 in the morning. Although it was new moon, I opted for mainly narrowband images because the nights weren't really astro-dark. I took some RGB data (about 2 hrs) but I eventually didn't process it in this image because I thought that the narrowband on itself is giving a really nice result.

The calibration and integration process was done in Astro Pixel Processor with 240 subframes. The final processing is done in PixInsight, I used Affinity Photo to adjust some minor controls and add my signature.

  • Date: June 12,13,14,16 - June, 2021
  • Integration Time: 10.75 hrs
  • Telescope: TS Photoline 130/910 at f5.5
  • Mount: Skywatcher EQ6-Synscan Go-To
  • Camera: ZWO ASI1600MM-Cool
  • Filters: Ha 54x300", SII 27x300", OIII 48x300"

TS Optics Apochromatische refractor AP 130/910 ED Triplet Photoline 2,5"-OAZ OTA

If you like my pictures and want to check out some astronomy gear I use, please feel free to go the Astromarket website via this affiliate link (picture left). If you make a purchase through this link, I get a small percentage of it with absolutely no extra cost for you. Thank you.