WR 134
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July 15, 2025
WR 134 is not easily distinguished in this image. It’s aone of the brighter star to the lower left of the teal-coloured arc. That structure is part of a nebula being blown out by the hot stellar winds coming from WR 134. This field is in Cygnus, a rich region for imaging during summer and fall in the Northern Hemisphere. All of the objects in this image are 5,000-6,000 light years away. In addition to WR 134, they include a couple of objects I’m currently imaging with the C14 EDGE, namely Sh2-104 at top left and Sh2-101 (the Tulip Nebula) at lower right. The entire field is just a little southeast of the gamma-Cyg field that I imaged last week with the same setup, except the filter. This image was made with an Optolong L-Ultimate filter, which passes 3 nm bands of hydrogen and oxygen emissions.
This is the second image for a new telescope: the Sky-Watcher Esprit 70 EDX. Unlike the Esprit 80mm, this scope has an image circle that can cover a full-frame 35mm sensor with pinpoint stars. The field of view is a whopping 4.5 x 3 degrees. Focus was stable over a 3C temperature range (I focused only twice, manually, at the start and middle of a 6.5-hour imaging run). They will hopefully be available to buy later in 2025.
Tekkies:
Acquisition, focusing, and control of Paramount MX mount and other equipment with N.I.N.A. and TheSkyX. Unguided, manual focus. Equipment control with Primalucelab Eagle 4 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Acquired under average transparency and seeing and a first-quarter Moon on the night of July 8-15, 2025.
First Light with Sky-Watcher Esprit 70 EDX refractor. QHY367C Pro camera with Optolong L-Quad Enhance filter.
86 x 5m with L-Ultimate filter = 7hr 10m
Preprocessing: The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, debayering, weighting, registration, integration and Drizzle integration of all frames (2x drizzle, 1.0 Drop Shrink).
Gradient Removal: SpectrophotometricFluxCalibration was applied followed by MultiscaleGradientCorrection.
Colour Calibration: BlurXterminator was applied to the RGB master with Correct Only selected, followed by SpectrophotometricColorCalibration.
Deconvolution: BlurXterminator was applied to the RGB master with Automatic psf , star sharpening set to 0.5, and non-stellar set to 0.9.
Linear Noise Reduction: NoiseXterminator was applied with settings Amount=0.9 and Iterations=4.
Stretching: HistogramTransformation was applied to make a pleasing image with background approximately 0.08.
Nonlinear Processing
Star Removal: StarXterminator was used to remove the stars from the master, with default settings, except Large Overlap was selected. The stars-only image was retained.
Nonlinear Noise Reduction: NoiseXterminator was applied with Amount=0.9 and Iterations = 4
Re-stretch: HistogramTransformation was used to boost contrast by moving the dark point to the toe of the histogram and slightly decreasing the mid-point slider.
Contrast Enhancement: LocalHistogramEqualization was applied twice. A Contrast Limit of 1.5 and 1 iteration was used for each LHE application (scale 50, strength 0.25; scale 320, strength 0.18).
Sharpening: MultiscaleMedianTransform was applied. (Layers 2 – 4 with strengths of 0.03 0.04, and 0.02 respectively).
Contrast, Brightness and Colour: Brightness, contrast, hue, and saturation were adjusted in several iterations using CurvesTransformation and the Jurgen Terpe Selective Color Correction script, with masks as required.
Stars-only steps: The CIE L* channel (i.e. the lightness channel) was extracted from the stars-only image and then applied to the star image as a mask. CurvesTransformation’s Saturation slider was used to boost colour in the stars.
Star Restoration: The PixelMath expression combine(starless, stars, op_screen()) was used to combine the starless starless image with the stars-only image. The StarReduction script was applied with small star protection enabled (Tranfer method, strength 0.4) to slightly reduce the larger stars.
Final Steps: Background, nebula, and star brightness, contrast, and saturation were adjusted in several iterations using CurvesTransformation with masks as required. ICCProfileTransformation (sRGB IEC61966-2.1; Relative Colorimetric with black point compensation) was applied prior to saving as a jpg. The finder chart was made using the FindingChart process. The annotated image was made with the AnnotateImage script.
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