Rosette Under a Full Moon

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Jared Willson Senior Member • Posts: 1,120
Rosette Under a Full Moon

Since Luna is so prominent right now, I decided to capture a narrow band image last night. Here is the Rosette Nebula through a 5nm H-Alpha filter.  Two hours total of data using three minute sub exposures. Darks, flats, and bias frames as well.

About the Subject:

The Rosette Nebula (also referred to as the skull nebula for reasons that are obvious with some versions/processing of the subject) is a molecular cloud in the constellation Monoceros. The mass of the nebula is estimated at 10,000 solar masses, and the distance is roughly 5,000 light years from Earth. That makes it relatively close by as these things go, so it is a favorite target for amateur astronomers just because of its size and brightness. On a dark night it is visible to the naked eye and easily seen in binoculars. The molecular cloud contains lots of hot, young stars that are putting out large amounts of ultraviolet light. This stellar radiation ionizes the surrounding gas causing the nebula to fluoresce.


  • Riccardi-Honders 305mm f/3.7 Astrograph (1125mm focal length)
  • QHY600 Monochrome Cooled Astronomy Camera
  • Astrodon GenII Hydrogen Alpha Filter
  • AP-1100GTO mount with Absolute Encoders


  • Captured in NINA, no guiding required for three minute subs
  • Calibrated in PixInsight using master darks, master bias (with overscan calibration), and twenty T shirt flats
  • Weighted batch pre-processing to ensure best frames were emphasized in stacking
  • MureDenoise algorithm to reduce noise in extreme shadows
  • Light deconvolution
  • Morphological Transformation to reduce star sizes before stretching
  • Stretched to taste
  • HDRMT to reduce the brightness in highlights (for eventual color version)
  • Imported to Lightroom where a tune curve was applied to enhance shadow area visibility and contrast

Rosette Nebula in Hydrogen Alpha Light

- Jared

 Jared Willson's gear list:Jared Willson's gear list
Leica Q2 Leica SL2 Hasselblad X1D II 50C Leica SL 90-280mm F2.8–4 Hasselblad XCD 30mm F3.5 +8 more
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