Abell 21: Medusa Nebula (ivnlpz)

Abell 21: Medusa Nebula

The Medusa Nebula spans approximately four light-years and lies at a distance of about 1500 light-years. Despite its size it is extremely dim and hard to observe. This beautiful planetary nebula is named after a dreadful creature from Greek mythology — the Gorgon Medusa. It is also known as Abell 21 or Sharpless 2-274 and is located in the constellation of Gemini.

Calibration frames:
- Dark library of 30 darks per exposure
- 20 flats per night per filter

Preprocessing:
- WBPP for calibration and cosmetization
- SubframeSelector using weight formula to prioritize SNRWeight
- StarAlignment
- LocalNormalization
- ImageIntegration

Processing filter images:
- MureDenoise
- DynamicCrop
- DBE
- EZ decon on Ha and Oiii using a processed star mask from StarXterminator
- LinearFit Oiii using Ha as the reference image
- EZ soft stretch

Nebula:
- PixelMath to create Foraxx HOO image
- LRGBCombination using Ha as the luminance image
- StarXterminator to remove stars
- CurvesTransformation
- ACDNR using mask
- LocalHistogramEqualization using RangeSelection masks
- DarkStructureEnhance
- Final Curves
- Export to tiff and run TopazDenoise

RGB_stars:
- Remove stretch on Ha and Oiii
- PixelMath to create RGB stars image
- PCC
- ScreenTransferFunction and HistrogramTransformation to stretch image
- CurvesTransformation
- SCNR

star_mask:
- StarXterminator on Nebula
- Extract luminance as mask is currently RGB
- HistogramTransformation to high clip and remove background
- MultiscaleLinearTransform
- MorphologicalTransformation

Final image:
- Apply star_mask to Nebula
- PixelMath to add RGB_stars to Nebula
- Touch up image in Photoshop to remove prominent halo around one star

PixInsight Addicts
Images from the EdgeHD Series
ZWO ASI1600MM/QHY163M
Abell Planetary Nebula
/r/astrophotography
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Texas Astronomy
Narrowband imaging
Suburban Astrophotography

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Status	Advanced success
Started	...
Astrometry.net job	5341256
PixInsight job	TGN34JEGBDW86HBIXQAX3YJT3CO6BPYZ
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	07h29m01s.837
RA (top/left)	07h28m11s.676
RA (top/right)	07h28m29s.825
RA (bottom/right)	07h29m51s.927
RA (bottom/left)	07h29m33s.919

Dec (center)	+13°15′01″.37
Dec (top/left)	+13°27′20″.34
Dec (top/right)	+12°59′31″.89
Dec (bottom/right)	+13°02′41″.67
Dec (bottom/left)	+13°30′30″.12

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