Messier 88
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May 23, 2026
Messier 88 (M88; NGC 4501) is a spiral galaxy, one of more than 2,000 galaxies in the Virgo Cluster. It’s about 50-60 million light years away from us in the constellation Coma Berenices. It’s inclined towards us at an angle of about 64 degrees, giving it a three-dimensional appearance. It is made up of about 400 billion stars, and more than 131,000 light years across. It’s relatively small on the sky, but that’s what this telescope specializes in! I included some Ha-filtered frames, which made a nice contribution to the image by subtly showing some red structures in the spiral arms near the core.
Tekkies:
Acquisition, focusing, and control of Paramount MX mount with N.I.N.A., TheSkyX. Guiding with PHD2. Primalucelab low-profile 2″ Essato focuser, ARCO rotator and Giotto flat panel. Equipment control with PrimaLuce Labs Eagle 4 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Average transparency and average or better seeing. Acquired under variable moon illumination from April 22 to May 16, 2026.
Celestron 14″ EDGE HD telescope at f/11 (3,931 mm focal length) and QHY600M-SBFL camera binned 2×2 with Optolong filters.
58 x 5m Red = 4hr 50m
55 x 5m Green = 4hr 35m
53 x 5m Blue = 4hr25m
30 x 5m Ha = 2hr 30m
Total: 16hr 20m
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Preprocessing: The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, weighting, registration, and integration.
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 all four masters using ImageIntegration with weighting by SNR.
Gradient Removal: DynamicBackgroundExtraction was applied to the SynthL, RGB and Ha masters.
Colour Calibration: BlurXterminator was applied to the RGB master with Correct Only selected, followed by SpectrophotometricColorCalibration.
Deconvolution: BlurXterminator was applied to the RGB, SynthL, and Ha 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, SynthL, and Ha masters with settings Amount=0.9 and Interations=4.
Ha Continuum Subtraction: The Seti Astro Continuum Subtraction script was used to remove continuum emissions from the Ha master using the red channel of the RGB master as the continuum reference image.
Stretching: MultiscaleAdaptiveStretch was applied to make a pleasing image from the RGB, SynthL and and Ha masters. Approximate background level after stretch was 0.09 for the RGB master, 0.1 for the SynthL master and 0.08 for the Ha master.
Nonlinear Processing
SynthL and RGB Combination: LRGBCombination was used to replace the CIE L* channel of the RGB image with the SynthL
Star Removal and processing: StarXterminator was used to remove the stars from the SynthLRGB master with Unscreen checked. Colour was increased in the stars-only image by increasing saturation using CurvesTransformation through a star mask.
Initial Saturation Boost: CurvesTransformation’s saturation tool was used to boost colour in the galaxy in the starless SynthLRGB image. A range mask made with RangeSelection was used to protect the background.
H-alpha Blending: The contiuum-subtracted Ha was added to the SynthLRGB image using Jurgen Terpe’s CombineHaWithRGB script.
Nonlinear Noise Reduction: NoiseXterminator was applied to the SynthLHaRGB image with settings Amount=0.9 and Iterations=5.
Contrast Enhancement: Jurgen Terpe’s MakeHDRImage was used to slightly compress the core of the galaxy. LocalHistogramEqualization was then applied three tunes. A Contrast Limit of 1.5 and 1 iteration was used for each application (scale 150, strength 0.35; scale 100, strength 0.2; and scale 40, strength 0.25).
Sharpening: BlurXterminator was used to sharpen the galaxy through a mask. Star sharpening set to zero, Automatic PSF unchecked, manual PSF at 3, and strength at 0.2.
Star Restoration: Stars were added back into the image using the PixelMath expression combine(starless, stars_only, op_screen())
Final Steps: Background, galaxy, and star brightness, contrast, and saturation were adjusted in several iterations using CurvesTransformation and Jurgen Terpe’s SelectiveColorCorrection script 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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