Reprocessing part of the Lion nebula centred on the Henry Draper star HD211982

S2, Ha and O3 data were captured by AstroDMx Capture with a QHY Minicam8, and a William Optics 81mm APO refractor with a 0.8 reducer/flattener.

Pixinsight was used to stack and register the S2, Ha and O3 data. Register the stars in the three monochrome images, remove the stars from the monochrome images and produce star images; delinearise the monochrome starless images and apply a slight Histogram transformation to produce similar brightness ranges across the monochrome images; combine the S2, Ha and O3 images into an SHO false colour image; apply the PixInsight Process of Narrowband normalisation; generate ‘RGB’ star images with Seti Astro’s NB to RGB Star Combination script with default green adjustment; denoise and sharpen the starless images.

Gimp3 was used to adjust the levels of the Narrowband normalised starless image and the Hue and saturation of the stars image. SetiAstroSuitePro was used for Texture and Clarity processing of the starless images. Gimp3 was used to screen back the stars and SetiAstroSuitePro was used to apply Cosmic Clarity stellar and non stellar sharpening and denoising. In addition, SetiAstroSuitePro was used at the initial starless narrowband normalised image stage to apply CLAHE: Contrast Limiting Adaptive Histogram Equalisation. CLAHE enhances local contrast and improves image details.

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Cosmic Clarity processing with SetiAstroSuitePro's new models

Narrowband normalised SHO image

Narrowband normalised SHO image with CLAHE enhancement

SHO image

Narrowband normalisation helps to bring out the golden hues and reduces the dominance of green, which is typical of the Hubble Palette.

Steve Wainwright and Nicola Mackin