ScienceDownEast | ScienceDownEast Astrophotography | Galaxies | NGC 6946 (Fireworks Galaxy) | Fireworks Galaxy NGC_6946 Clear+Triad

Fireworks Galaxy NGC_6946 Clear+Triad

NGC 6946 The Fireworks Galaxy. NGC 6946, sometimes referred to as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years similar to the distance of M101 (NGC 5457) in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster.

The galaxy was discovered by William Herschel on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a D25 B-band isophotal diameter of 87,300 light-years. It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way. Due to its prodigious star formation it has been classified as an active starburst galaxy. NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center. Various unusual celestial objects have been observed within NGC 6946. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars. There are also two regions of unusual dark lanes of nebulosity, while within the spiral arms several regions appear devoid of stars and gaseous hydrogen, some spanning up to two kiloparsecs across.A third peculiar object, discovered in 1967, is now known as "Hodge's Complex". -- Wikipedia

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Total image time was 4 hours and 40 min with No filter, and 7.75 hours with Triad Quad Ultra Filter

Exposure 28x10 min + 31*15 min.
GAIN 100
Camera ToupTek ATR2600C [6224 x 4168]
Optics 120mm Skywatcher Esprit on a Proxisky UMi20S Strain Wave mount
Guiding ToupTek GPM462M using Phd2
Controller Kstars on MeLe Quieter 4C
Filter None + Triad Quad Ultra
Location Myra River, Cape Breton, and Lower Sackville, Nova Scotia.
Date 2025-08-27, 2025-08-38, 2025-08-31
Processing Processed in PixInsight.
SetiAstro Automatic DBE
SpectrophotometricColourCalibration
BlurXTerminator
NoiseXTerminator
Generalized Hyperbolic Stretch (GHS) (using Blair MacDonald's excellent YT Tutorial)
StarXTerminator
In the starless image: CurvesTransformation, HDRMultiscaleTransform
PixelMath recombination ~((~stars)*(~starless))
similar treatment of the FIlter data and then a simple integration of them



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