NGC 6946 & NGC 6939 – A Wide-Field View
Key Field Data
Main objects: NGC 6946 (Fireworks Galaxy) and NGC 6939
Constellation: Cepheus, near the Cygnus border
Field of view: approximately 4.4° × 3.4°
NGC 6946: Spiral galaxy, approximately 25 million light-years away
NGC 6939: Open star cluster within the Milky Way
Distance to NGC 6939: approximately 4,000 light-years
Angular separation: approximately 40 arcminutes
Additional objects: Faint PGC galaxies, foreground Milky Way stars and interstellar dust
Description
This wide-field image captures NGC 6946, the Fireworks Galaxy, alongside the open cluster NGC 6939, within a dense stellar region near the Galactic plane.
Acquired with the William Optics RedCat 51 III WIFD, the 4.4° × 3.4° field reveals thousands of Milky Way stars, interstellar dust and numerous distant galaxies, providing a perspective that extends far beyond the close-up view of NGC 6946.
NGC 6939 – A Neighbour Only in the Sky
Separated by approximately 40 arcminutes, NGC 6939 and NGC 6946 appear close together but are physically unrelated.
NGC 6939 is an open cluster approximately 4,000 light-years away, while NGC 6946 lies some 25 million light-yearsfrom Earth, over 6,000 times farther away.
Their apparent proximity illustrates how objects at vastly different distances can share the same line of sight.
Looking Through the Milky Way
Located close to the Galactic plane, this field contains an exceptionally dense foreground of stars belonging to our own Galaxy.
Their blue, white, yellow and orange colours reflect differences in stellar temperature, while interstellar dust absorbs and reddens light, producing subtle dark structures across the background.
A Universe Hidden Between the Stars
Beyond the Milky Way foreground, numerous faint galaxies are visible, including PGC 64878, PGC 166192, PGC 166193, PGC 166194 and PGC 166686.
Many appear as tiny diffuse or elongated patches, almost indistinguishable from the surrounding stars without annotation, despite representing entire galaxies at enormous distances.
Layers of Distance
The photograph combines several distinct astronomical scales: foreground Milky Way stars, the open cluster NGC 6939, the distant spiral NGC 6946 and numerous background galaxies.
Although projected onto the same image, these objects occupy entirely different regions of space, illustrating the enormous depth concealed within a seemingly flat star field.
Why the Wide Field Matters
Unlike a close-up image, which highlights NGC 6946's spiral structure, this wider perspective reveals its apparent surroundings and the extraordinary density of the Galactic foreground.
The pairing with NGC 6939 demonstrates a fundamental astronomical principle: apparent proximity in the sky does not imply physical proximity in space.
Looking Back in Time
This image brings together objects whose light began travelling towards Earth at dramatically different moments in history.
The light from NGC 6946 departed approximately 25 million years ago, during the late Oligocene, when early apes and other mammals were evolving, long before the appearance of humans.
By contrast, the light from NGC 6939 began its journey around 2000 BC, during the Bronze Age. Ancient Egypt was entering its Middle Kingdom period, Mesopotamian civilisations were flourishing, and humans were developing cities, trade networks, writing and sophisticated metalworking.
The foreground Milky Way stars represent more recent periods, while distant background galaxies may reveal much earlier epochs.
Within a single photograph, light from the age of ancient civilisations meets light that began its journey millions of years before humanity existed.
Image Data
Total integration time: 17h 59m 30s
Integration by filter:
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L-Pro: 5h (60 × 300")
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Red: 4h 25m
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Green: 4h 14m 30s
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Blue: 4h 20m
Equipment:
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Telescope: William Optics RedCat 51 III WIFD
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Camera: ToupTek ATR2600M
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Mount: 10Micron GM2000 HPS II
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Filters: Optolong L-Pro, Red, Green, Blue 2"
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Accessories: ToupTek AAF Electric Focuser, WandererAstro WandererCover V4-EC
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
For further information and the full-resolution image, visit AstroBin: