NGC 6946
NGC 6946 – star formation in the Fireworks Galaxy
Blue arms, pink knots and brown dust lanes curl around a bright centre. NGC 6946 presents its disc almost face-on. Unlike the narrow silhouette of NGC 891, it allows us to follow the branching spiral pattern as it gradually fades into the faint outer light.
About 25 million years in transit. A distance measurement based on red giant stars gives roughly 7.72 megaparsecs, or 25 million light-years. The galaxy lies towards the border of Cygnus and Cepheus. The many sharply imaged stars across the field belong to the foreground Milky Way; they are not individually resolved suns in NGC 6946.
Star-forming regions in another disc. Pink concentrations along the arms are consistent with H II regions, where young, hot stars ionise surrounding gas. Young stellar populations contribute to the blue areas. Between them, dust obscures the background light and defines the inner spiral structure. This is broadband RGB imaging: colour alone does not replace spectroscopy or establish a catalogue identification for an individual knot.
Why “Fireworks Galaxy”? The nickname refers to the many supernovae observed there historically. It does not mean that every bright point in this image is an explosion, and no current supernova is identified in this exposure. The three close-ups instead explore the structured inner region, an outer arm and the transition from the galaxy’s edge to foreground stars.
Where in the sky
The rectangle is this image's real field of view, with its measured rotation — not a symbol. Constellation figures and star positions come from SIMBAD.
7 entries sit within 30° of each other here — click a field to jump to it.
Crops
Dust and star formation
Dust spirals and glowing knots
10.3′ × 4.9′·20h 34m 51.48s +60° 10′ 48.9″
This close-up reveals the finely structured inner disc. Dark lanes run between bright stellar clouds, with pink knots accenting the arms farther out. A central marker and an arm landmark provide orientation. The brightness of this processed image cannot yield reliable star counts or local star-formation rates.
The outer arm
From the centre to an outer spiral arm
6.0′ × 9.7′·20h 34m 35.44s +60° 12′ 20.6″
The portrait framing follows an arm from the bright inner region into the fainter outer disc. Pink concentrations and blue patches form an interrupted sequence rather than a smooth line. The upper structural marker identifies a visible arm section; it is not a supernova marker.
Edge and foreground
The galaxy’s edge and Milky Way stars
8.7′ × 6.5′·20h 34m 51.78s +60° 04′ 42.9″
The outer arms fade into a faint blue-toned fringe. Prominent blue and orange Milky Way stars stand in front of it. Their apparent proximity to the galaxy’s edge is a line-of-sight overlap. The structural marker locates the faint arm section without treating nearby foreground stars as galaxy members.
Acquisition and processing
Acquisition. 19 × 120 s + 48 × 180 s = 3 h 2 min, recorded between 9 and 14 September 2026 in Friedrichsdorf. Camera: ZWO ASI585MC Air, Askar 120APO at 840 mm focal length, broadband, gain 200. Exposure counts and dates come from the acquisition metadata and integration report; the telescope identification was confirmed by the photographer.
Processing. All 67 selected light frames were registered, locally normalised and integrated; the run includes 2× drizzle integration. The documented PiMagic workflow uses spectrophotometric colour calibration, gradient correction, sharpening, noise reduction and separate star and object layers. Drizzle refines the sampling grid but does not guarantee twice the actual resolution. This entry uses the curated AVIF version with an HDR gain map and an SDR rendering.
Field and overlays. The current file measures 3869 × 2580 pixels. Its astrometric solution gives approximately 0.355″ per pixel and a field of 0.382° × 0.255°. Catalogue positions and explicitly identified structural landmarks are projected through this solution. Marker circles are locating aids, not measurements of object boundaries.