NEBULAE
The Wizard Nebula, wide field
— NGC 7380 —
Processed by Nicolas Rolland, Paris. 11.6 hours gathered by Grand Mesa Observatory at Whitewater, Colorado, USA.
This is the same nebula as the seventy-hour version, seen from further back. The frame runs 1.39 by 1.30 degrees, roughly two and a half times the area, and it holds the whole of NGC 7380 with room around it — the cluster, the nebula it lit, and the field it sits in.
A nebula wrapped around a young cluster
Caroline Herschel found the open cluster in 1787, and the nebula around it entered the Sharpless catalogue in 1959 as Sh2-142. It lies about 8,500 light-years away in Cepheus. The cluster spans some 20 light-years and is between 4 and 11 million years old, which is young enough that the gas it formed from is still there — what the frame shows is a cluster in the act of clearing its own nursery.
DH Cephei does the ionising
The pair of massive O-type stars at the cluster's centre, catalogued together as DH Cephei, is the primary ionising source for the whole HII region. At this focal length their effect is easier to read than in a tight crop: the nebula is visibly brighter and more structured close to them, and thins out towards the edges of the field where the ultraviolet no longer reaches with the same force.
Mapped nebula, real stars
The nebula is rendered in the Hubble palette — SII to red, Ha to green, OIII to blue — so its colours are assigned rather than observed. The stars are not. Red, green and blue filters were shot alongside the narrowband set and used for the stars alone, which means every point of light in this frame carries its true colour while everything around it carries a mapped one. It is a small distinction and it changes how the image reads: the star field stays honest, and the nebula stays legible.
