NGC 6888, The Crescent Nebula in Cygnus

Background information and spectra

aka: Sharpless 105, Caldwell 27 The Crescent nebula, discovered in 1792 by William Hrschel, is an emission nebula. It arises from the stellar wind from the Wolf-Rayet star WR 136. This star has a surface temperature of over 70,000 K and is emitting a strong stellar wind. The energetic wind is interacting with material blown off the star when it was in the red giant phase about 300,000 years ago. This interaction, together with the intense radiation from the star, is causing the gases to fluoresce. Image of NGC6888 is here Spectra of various regions of NGC6888

Spectra show weak oxygen, strong nitrogen and traces of heliom, sulphur.and argon.

Spectra taken on 2025-08-10 with HAG 24 RC 'David Harris' telescope, Lhires III spectroscope 300gr/mm
ZWO ASI2600MM Pro camera. 6 x 120sec, analysis with RSpec software.

2025-08-10 @ 22:32 UT