NGC 6712
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June 8, 2025
NGC 6712 is a relatively small globular cluster located in Scutum. Its mass is about 94,000 times the Sun’s, and it lies about 26,400 light years from Earth. It is set in a nice, rich star field near open cluster M11. NGC 6712 is estimated to be 10.4 billion years old. One of the things I love about globulars is how different they look from each other, both the cluster, and the surrounding star field. For example, look at these portraits of M13, NGC 5466 and NGC 5053 imaged with the same equipment used for the current shot of NGC 6712.
I imaged NGC 6712 with a shorter focal length on July 7, 2022, sharing the frame with planetary nebula IC 1295. Check it out!
Tekkies:
Acquisition, focusing, and control of Paramount MX mount with N.I.N.A., 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 minimal moonlight, good transparency and average seeing June 1-2, 2025.
Celestron 14″ EDGE HD telescope at f/11 (3,940 mm focal length) and QHY600M camera binned 2×2 with Optolong filters.
13 x 5m Red = 65m
12 x 5m Green = 60m
12 x 5m Blue = 60m
Total: 3hr 05m
Preprocessing: The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, weighting, registration, local normalization, and integration of all frames.
RGB master: An RGB image was made from the Red, Green and Blue masters using ChannelCombination in RGB mode.
Synthetic Luminance: A SynthL was made by integrating the three masters, weighted by SNR, with no pixel rejection.
Gradient Removal: DBE was used to remove gradients from the RGB and SynthL masters.
Colour Calibration: SpectrophotometricColorCalibration was used to calibrate the RGB master.
Deconvolution: BlurXterminator was applied to the RGB and SynthL masters with Automatic psf , star sharpening set to 0.35, and non-stellar set to 0.15.
Linear Noise Reduction: NoiseXterminator was applied to the RGB and SynthL masters with settings Amount=0.9 and Iterations=5
Stretching: HistogramTransformation was applied to the RGB and SynthL masters to make pleasing images. Approximate background level after stretch was 0.1 for SynthL and 0.09 for RGB.
Nonlinear Processing
Combinining SynthL and RGB: LRGBCombination was used to replace the lightness channel of the RGB image with the SynthL.
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.
Final Steps: Background, globular cluster, and star brightness, contrast, hue, 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.
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