Abell 426
Click image for full size version
January 10, 2025
Abell 426 is also known as the Perseus Galaxy Cluster and, not surprisingly, is located in Perseus. This image captures about 1/3 of the cluster and shows hundreds of the cluster’s members. Perseus A is the large galaxy left of centre. Also known as NGC 1275, this galaxy lies near the centre of the galaxy cluster, and is 237 million light years away. It is a radio galaxy, emitting strongly in the radio frequency. The centre of the galaxy may contain a supermassive black hole with a mass more than 340 million times the mass of the Sun. Abell 426 is one of the most massive objects in the known universe.
I created an annotated image that shows of the many galaxies in this field. Those whose names begin with NGC, IC, and PGC are galaxies that are part of Abell 426 (they also have larger text labels). Objects whose names begin with MQ, SDSS, and WISEA are all distant quasars billions of light years from us. And many of the galaxies are not labeled at all, but are part of Abell 426’s cast of thousands.
Tekkies:
Acquisition, focusing, and control of Paramount MX mount and other equipment with N.I.N.A. and TheSkyX. Guiding with PHD2. Primalucelab low-profile 2″ Essato focuser and ARCO rotator. Equipment control with PrimaLuce Labs Eagle 4 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Data acquired under moderate moonlight, average transparency and below average seeing December 28, 2024 – January 9, 2025.
Celestron 14″ EDGE HD telescope at f/11 (3,912 mm focal length) and QHY600M camera binned 2×2 with Optolong filters.
17 x 5m and 33 x 2m Red = 2hr 31m
17 x 5m and 32 x 2m Green = 2hr 29m
16 x 5m and 32 x 2m Blue = 2hr 24m
Total: 7hr 24m
Preprocessing: The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, weighting, registration, integration and Drizzle integration of all frames.
RGB and SynthL masters: A master RGB image was made from the Red, Green and Blue Drizzled masters using ChannelCombination in RGB mode. A synthetic luminance (SynthL) master was made from the R-G-B masters using ImageIntegration with weighting by SNR.
Gradient Removal: SpectrophtometricFluxCalibration was applied to the RGB master, followed by MultiscaleGradientCorrection. GraXpert was applied to the SynthL and RGB masters.
Colour Calibration: BlurXterminator was applied to the RGB master with Correct Only selected, followed by SpectrophotometricColorCalibration.
Deconvolution: BlurXterminator was applied to the RGB and SynthL masters with Automatic psf , star sharpening set to 0.5, and non-stellar set to 0.9.
Linear Noise Reduction: NoiseXterminator was applied to the RGB and SynthL masters with settings Amount=0.9 and Detail=0.25
Stretching: HistogramTransformation was applied to make a pleasing image from the RGB and SynthL masters. Approximate background level after stretch was 0.1 for SynthL and 0.08 for RGB.
Nonlinear Processing
Combining EGB and SynthL: LRGBCombination was used to replace the lightness channel of the RGB image with SynthL.
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 used to reduce noise in the background areas of the SynthRGB master with Amount=0.9 and Detail=0.15.
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.
Blemish Repair: CloneStamp was used to correct a few small defects in the starless image.
Contrast Enhancement: LocalHistogramEqualization was applied twice. A Contrast Limit of 1.5 and 1 iteration was used for each LHE application (scale 40, strength 0.25; scale 90, strength 0.2).
Sharpening: MultiscaleMedianTransform was applied. (Layers 2 – 4 with strengths of 0.07, 0.07, and 0.05, respectively), using a mask to select only the galaxies.
Contrast, Brightness and Colour: Galaxy brightness, contrast, and saturation were adjusted in several iterations using CurvesTransformation 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 0.35) to slightly reduce the larger stars.
Final Steps: Background, galaxy, 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.
Stunning image!!
Thank you!