Barnard’s “E” (B142 & B143)

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August 29, 2020

This image shows Barnard 142 (top) and 143, together known as Barnard’s E. Dark nebulae are made up of soot and dust that block out the light of the stars behind them.  They can create some really interesting patterns. The Horsehead Nebula (a.k.a Barnard 33) is an example of a dark nebula silhouetted against a red reflection nebula.   But dark nebulae are often framed against the rich starry background of the Milky Way.  That’s the case in the attached image, where B142 and B143 together make a shape that looks like an “E” or a “5.”  This object is located about 2000 light years from us in the constellation of Aquila, the Eagle.  

Tekkies:
Acquisition, focusing, and control of Paramount MX mount (unguided) with TheSkyX. Focus with Optec DirectSync motor and controller. Automation with CCDCommander. Equipment control with PrimaLuce Labs Eagle 3 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Average transparency and seeing. Data acquired June 18, 2020 in a moonless sky.

Luminance: Sky-Watcher Esprit 150 f/7 refractor and QHY 16200-A camera with Optolong UV/IR filter
Chrominance: Takahashi FSQ-106 ED IV @ f/3.6 and QHY367C one-shot colour camera with Optolong UV/IR filter

Data Reduction and Initial Processing
Preprocessing: The WeightedBatchPreProcessing script was used to create a Luminance master frame (from the mono camera) and a Drizzled RGB master frame (from the one-shot colour camera).

Gradient Removal: DBE was applied to L and RGB masters using Subtraction.

Colour
Channel Registration:  To improve channel registration, the colour channels of the RGB master were extracted and aligned with StarAlignment, using Thin Plate Splines with Distortion Correction and the luminance master as the reference frame. The registered colour channels were recombined with ChannelCombination.

Colour Balancing:  Colour was balanced with ColorCalibration.

Linear Noise Reduction: MultiscaleLinearTransform was used to reduce noise in the background areas, using an internal mask to protect bright structures. Layer settings for threshold and strength: Layer 1: 5.0 0.85, 2 iterations; Layer 2: 3.5, 0.75, 2 iterations.

Stretching:  HistogramTransformation was applied to make a pleasing, bright image, with background set to an intensity of approximately 0.10.

Lightness
Linear Noise Reduction:  MultiscaleLinearTransform was used to reduce noise in the background areas, using an internal mask to protect bright stars. Layer settings for threshold and strength: Layer 1: 3.0 0.85, 1 iterations; Layer 2: 2.0, 0.75, 2 iterations.

Stretching:  HistogramTransformation was applied to make a pleasing, bright image, with background set to an intensity of approximately 0.10.

Combining Lightness and Colour Images

LRGB Combination: The lightness image was applied to the RGB image using LRGBCombination with default settings.