C 443 Wide Field – Jellyfish Nebula and Its Cosmic Environment
Key Scientific Data
Main object: IC 443 – Jellyfish Nebula
Object type: Supernova remnant
Constellation: Gemini
Other designations: IC 443, Sh2-248, Jellyfish Nebula
Distance from Earth: approximately 5,000 light-years
Apparent size of IC 443: approximately 45–50 arcminutes
Origin: Core-collapse supernova of a massive star
Estimated age: uncertain, from a few thousand to approximately 30,000 years
Compact object: CXOU J061705.3+222127 (J0617), likely a neutron star
Associated structure: Pulsar wind nebula
Other prominent objects: IC 444, Sh2-249, M35
Bright stars: Tejat Prior (η Gem) and Tejat Posterior (μ Gem)
Field of view: approximately 5.38° × 3.58°
Light-travel time: approximately 5,000 years for IC 443
Description
This wide-field image of Gemini reveals IC 443, the Jellyfish Nebula, within a vast and complex region of the Milky Way containing emission nebulae, dark interstellar clouds and rich stellar fields.
Unlike a close-up observation, the wider perspective shows the supernova remnant surrounded by extensive nebulosity associated with IC 444 and Sh2-249, while the open cluster M35 adds a contrasting concentration of stars.
The result is a remarkable view of an interstellar landscape, where the remains of a stellar explosion coexist with glowing gas, obscuring dust and stellar populations of different origins.
IC 443 – The Jellyfish Nebula
Located approximately 5,000 light-years from Earth, IC 443 is the expanding remnant of a massive star that ended its life in a core-collapse supernova.
Its characteristic curved shell and delicate filaments trace shock waves interacting with the surrounding interstellar medium.
The remnant's irregular shape reflects variations in the density of the gas encountered by the expanding shock, producing bright arcs, fragmented structures and diffuse emission.
The explosion probably left behind a neutron star, CXOU J061705.3+222127, associated with a pulsar wind nebula detected primarily through X-ray observations.
IC 444, Sh2-249 and the Dark Clouds
The extensive nebulosity surrounding IC 443 includes IC 444 and Sh2-249, together with large concentrations of interstellar gas and dust.
Bright reddish regions trace emission from ionised hydrogen, while dark clouds obscure background light, creating striking silhouettes across the field.
These structures illustrate the complex distribution of matter within the Milky Way, where glowing gas and dense dust clouds can appear closely intertwined.
Although they share the same apparent region of sky, the different structures are not necessarily physically connected or produced by the same processes.
M35 – An Open Star Cluster
The prominent stellar concentration towards the left side of the image is Messier 35, a rich open cluster.
Unlike the surrounding nebulae, M35 consists of stars that formed together from the same molecular cloud and remain gravitationally associated.
Its presence provides an interesting contrast between stellar formation, interstellar material and the aftermath of stellar death, all visible within a single wide-field composition.
A Wider Perspective on the Jellyfish
The William Optics RedCat 51 reveals the large-scale environment surrounding IC 443, complementing the higher-resolution observations obtained with the Artesky ARTEC 250 Pro.
While the longer focal length highlights individual shock fronts and fine filaments, this wider field shows how the remnant occupies only a small portion of a much larger interstellar complex.
The Optolong L-Ultimate dual-band filter isolates primarily Hα and OIII emission, revealing the distribution of ionised gas, while the broadband exposures preserve the surrounding stellar field.
Together, these two imaging approaches provide complementary perspectives: one emphasises the structure of the remnant, while the other reveals its Galactic context.
Looking Back in Time
The light captured from IC 443 began its journey approximately 5,000 years ago, around 3000 BC.
At that time, the earliest dynasties of ancient Egypt were emerging, cities were flourishing in Mesopotamia, and the great pyramids of Giza had not yet been constructed.
While those photons travelled across the Milky Way, the supernova remnant continued expanding and interacting with the surrounding interstellar gas.
The other objects in this photograph lie at different distances, meaning that each is observed at a different moment in cosmic history.
This wide-field image therefore reveals not only different structures within the Milky Way, but also different layers of astronomical time.
Image Data
Total integration time: 9h 13m 20s
Integration by filter:
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LP: 33m 20s (100 × 20")
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Multiband: 8h 40m (52 × 600")
Equipment:
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Telescope: William Optics RedCat / Cat 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-QEF 2", Optolong L-Ultimate 2"
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Accessories: ToupTek AAF Electric Focuser, WandererAstro WandererBox Pro V3, ZWO EFW 7×2"
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
For further details and the full-resolution image, visit AstroBin: