Rosette Nebula Complex — NGC 2237 – 2246
The Rosette Nebula Complex is a vast, flower-shaped cloud of gas and dust about
5,200 light-years away in
Monoceros. At its core, the young cluster NGC 2244 powers a glowing ring of hydrogen with fierce ultraviolet
light and stellar winds, carving a central cavity roughly 50 light-years wide. Dense filaments and dark petals trace
where new stars are forming along the nebula’s rim, giving this enormous H II region
its delicate, rose-like appearance.
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| Distance from Earth | ≈ 5,200 light-years |
| Overall Diameter | ≈ 130 light-years |
| Central Cavity | ≈ 50 light-years wide |
| Apparent Size | ≈ 1.3° × 1.3° (3 × Moon) |
| Associated Cluster | NGC 2244 |
| Dominant Emissions | H-α, [O III], [S II] |
| Cluster Age | ≈ 4 million years |
| Identified YSOs | > 300 (infrared surveys) |
NGC 2252 — Nearby Open Cluster (Line of Sight)
NGC 2252 is an open cluster in Monoceros
seen near the Rosette but not part of the nebula itself. It lies at a different distance along the same line of sight.
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12 Mon — Foreground Star
12 Monocerotis (12 Mon) is a bright foreground star projected against the Rosette. It’s not physically related to the nebula
but provides a helpful reference point in images.
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Targets & WCS
Mapping & Constellations
Equipment & Integration
Imaging Setup
- Scope: William Optics GRAN-TURISMO 81 IV
- Camera: ZWO ASI2600MC Pro
- Filters: Baader 3.5 / 4 nm Ultra-Narrowband Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)
- Mount: iOptron CEM120EC2
- Guiding: ZWO ASI290MM Mini Camera, WO UniGuide 50 mm f/4.0 scope
Integration
- Hα: 45 × 300 s = 3 h 45 m
- O III: 45 × 300 s = 3 h 45 m
- S II: 45 × 300 s = 3 h 45 m
- Total: 11 h 15 m
Notes / Processing
Stacking was performed using Astro Pixel Processor, which handled calibration and initial integration of the data while producing individual stretched channels for H-alpha, S II, and O III. Star reduction was completed with StarNet v2 to isolate nebular detail and better emphasize the main structures. The combined processing was carried out in Affinity Photo using its dedicated astrophotography tools, along with James Riston’s macro toolset for enhanced workflow control. The three channels were merged and color-mapped in the Hubble Palette (SHO), followed by additional stretching and refinement of each channel. Final steps included targeted noise reduction, sharpening, and overall tonal balancing—adjusting brightness, contrast, and color balance—to produce the finished image.
Rosette Nebula Complex — Detailed Description & Further Reading
The Rosette Nebula Complex (cataloged as NGC 2237 – 2246) is one of the Milky Way’s most striking H II regions—an immense cloud of ionized hydrogen and dust spanning about 130 light-years. Located near the outer edge of the Orion Arm, it is illuminated and shaped by the open cluster NGC 2244, whose massive O- and B-type stars are only a few million years old. Their intense ultraviolet radiation ionizes hydrogen, producing vivid H-alpha emission, while stellar winds excavate the nebula’s ≈50 light-year cavity. The expanding bubble compresses nearby gas, triggering secondary star formation along the ring’s edge—a process called radiation-driven implosion. Infrared and X-ray surveys from Spitzer, Herschel, and Chandra reveal hundreds of young stellar objects (YSOs) and protostars embedded in the dusty filaments.
The complex includes several overlapping catalog designations—NGC 2237, 2238, 2239, and 2246—that describe different luminous sections of the same structure, while the encompassing Rosette Molecular Cloud (RMC) holds tens of thousands of solar masses of cold gas behind the emission shell. Spectrally, the region glows in H-alpha (656.3 nm), [O III] (500.7 nm), and [S II] (672.4 nm), producing the vivid red-blue-gold hues seen in narrowband imagery.
Further Reading
NGC 2252 — Detailed Description & Further Reading
Cataloged separately from the Rosette complex, NGC 2252 appears in the same sky area but is a distinct stellar group. Its stars are older and do not illuminate or shape the Rosette; the juxtaposition is purely geometric from our viewpoint on Earth.
12 Mon — Detailed Description & Further Reading
12 Monocerotis lies much closer (or farther) than the Rosette Nebula and simply happens to sit along the same line of sight from Earth. Such alignments are common in wide-field astrophotography and can make unrelated objects appear connected when they are not.