NGC 2237 – The Rosette Nebula

The Rosette Nebula, cataloged as NGC 2237-2246, is an H II region (emission nebula) and its associated open cluster of stars located in the constellation Monoceros. The nebula is situated approximately 4,900 light-years from Earth and spans about 130 light-years in diameter, making it one of the largest and most spectacular emission nebulae visible in our galaxy.

The Rosette Nebula is named for its distinctive rose-like appearance when viewed through large telescopes. It is illuminated and ionized by a central cluster of stars, creating the characteristic reddish-pink glow produced by hydrogen-alpha emission. The nebula's structure reveals intricate filaments and dark dust lanes that provide contrast against the brighter emission regions, making it a challenging and rewarding target for astrophotography.

Acquisition

• Subject: NGC 2237, SH2-275
• Location: Palm Harbor, FL; Bortle 7
• Date: 2026-01-27, 2026-01-28
• Lights: 5hrs
  • 100 x 180s RGB
  • Total integration: 100 frames × 180s = 18,000 seconds = 5.0 hours
• Dark:
  • 20 x 0.3s
  • 20 x 180s
• Flats:
  • 30
• Bias: N/A
• Gain: 100
• Bin: 1×1

Equipment

• Mount: ZWO AM5
• Telescope: SharpStar 150mm f/2.8 HNT
  • Focal Length: 420mm
  • Focal Ratio: f/2.8
• Imaging Camera: ZWO ASI2600MC Pro, cooled 0°C (APC mode)
• Filter:
  • Antilia ALP-T Highspeed Dualband Ha, O3
• Guide Scope: William Optics UniGuide 32mm f/3.75
• Guide Camera: ZWO ASI120MM Mini
• Auto Focuser: ZWO EAF
• Computer: ZWO ASIAir Pro

Processing

• PixInsight 1.9.3
  • Weighted Batch Preprocessing v2.9.1
  • Dark frame integration (average combination, winsorized sigma clipping)
  • Flat frame integration
  • Light frame calibration and debayering
  • Image integration using drizzle (2x upsampling)
  • Photometric Color Calibration
  • GraXpert sky background subtraction
  • BlurXterminator deconvolution
  • NoiseXterminator noise reduction
  • Generalized Hyperbolic Stretch tone mapping
  • StarXTerminator star removal and restoration
  • Curves Transformation color and contrast adjustment
  • Star reintegration