NGC 7331 Galaxy Group and Stephan's Quintet
Also Known as: Caldwell 30 (NGC 7331), Arp 319 (Stephan's Quintet)
Object Type: Unbarred Spiral Galaxy (NGC 7331)
Constellation: Pegasus
Distance from Earth: 39.8 million light years (NGC 7331), 39 million light years (NGC 7331), 210-240 million light years (Stephan's Quintet)
Apparent Magnitude: 10.4
Coordinates: RA 22H 37M 04.1S DEC 34 deg 24 min 56 sec (NCG 7331), RA 22H 35M 57.5S DEC 33 deg 57 min 36 sec (Stephan's Quintet)
Actual Size: 120,000 light years in diameter (NGC 7331)
Apparent Dimensions: 10.5 arc-minutes x 3.7 arc-minutes (NGC 7331)
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Environmental Data
Date: August 22, 2025 Start Time: 8:45PM End Time: 3:31AM SQM: 19.25
Moon Age: 29.0 days Moonrise: 5:03AM Moon Illumination: 0.4%
Temperature: 67.6 degrees F Humidity: 63% Dew Point: 54.5 degrees F
Location: Westport, Massachusetts 02790 Sky Condition: Clear
Comment:
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Imaging Scope Data
Mount: iOptron CEM120 Camera: ZWO ASI2600 monochrome Focuser: Optec QuickSync FT20
Telescope: Celestron 11 inch SCT Edge Focal Length: 1960mm
Focal Reducer/Field Flattener: 0.7 focal reducer Dew Heater: Kendrick dew strip
Filter Wheel : ZWO EFW 7 position 2 inch Filter(s): Baader Lum CMOS optimized 2 inch, Baader RED CMOS optimized 2 inch, Baader GREEN CMOS optimized 2 inch, Baader BLUE CMOS optimized 2 inch
Rotator: Pegasus Falcon 2 Power Control: Pegasus Ultimate Powerbox V2
Imaging Software
Mount: iOptron Commander Focuser: Optec FocusLynx Commander
Imaging: Sequence Generator Pro Platesolve: ASTAP Rotator/Control: Pegasus Unity Platform
Imaging Status
Imaging Software: Sequence Generated Focus HFR 2.72 Platesolve: Success on 2nd attempt
Guide Scope Data
Telescope: Stellarvue SVX130 refractor Camera: ZWO ASI290 Focuser: Optec DirectSync SV35
Dew Heater: Kendrick dew strip Software: PHD2 Exposure: 2 sec Binning: 1x1 Tracking Result: 0.55 arc-seconds RMS
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Images Taken
Number of light frames (LUM): 60 Duration: 2 minutes Gain: 100
Number of light frames (Red): 40 Duration: 2 minutes Gain: 100
Number of light frames (Green): 40 Duration: 2 minutes Gain: 100
Number of light frames (Blue: 40 Duration: 2 minutes Gain: 100
Camera Temperature: 0 degrees C Binning: 1x1 F-Stop: 7.0
Total Integration Time: 6 hours
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Number of flat frames (LUM): 25 Duration: 0.025 Gain:100
Number of flat frames (Red): 25 Duration: 0.08 Gain: 100
Number of flat frames (Green): 25 Duration: 0.051 Gain: 100
Number of flat frames (Blue): 25 Duration: 0.11 Gain: 100
Flat Field Illumination: All-Pro 'Spike-a-Flat Field standard' illuminated panel
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Number of Dark frames: 50 (from library) Duration: 2 minutes Gain: 100
Number of Bias frames: 50 (from library) Duration: 0.001 seconds Gain: 100
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Imaging Processing
Imaging Processing Software: PixInsight
Processes utilized: Linear - calibration/integration:
For each of the LUM, RED, GREEN, and BLUE lights: Flats ImageCalibration with Master Bias, Flat ImageIntegration, Images ImageCalibration with Flat Master & Dark Master, SubFrameSelector
StarAlign all calibrated lights using best LUM image as reference, ImageIntegration of each of the LUM, RED, GREEN, and BLUE sets
Linear - Background extraction, Color correction, deconvolution, noise reduction:
LUM DynamicCrop, GraXpert, BlurXTerminator, NoiseXterminator
RED/GREEN/BLUE DynamicCrop, GraXpert, ChannelCombination to create color image using only Red/Green/Blue, ImageSolve, SpectroPhotometricColorCalibration, BlurXTerminator, NoiseXterminator
Non-Linear:
LUM: GeneralizedHyperbolicStretch script, MultiscaleLinearTransfrom to sharpen
COLOR: GeneralizedHyperbolicStretch script, CurvesTransformation, HistogramTransformation to darken background
ImageBlend of Luminance and color images, HistogramTransformation to darken background, MultiscaleLinearTransform to smoothen, CurvesTransformation to increase chrominance.
Notes:
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