NGC6946

Constellation: Cepheus        Distance: 19 million lightyears

NGC6946

Click for full resolution (1537 x 1168)

Image spcefications:
  • Exposure: 11 hours, LRGB = 230:50:50:50 minutes, 5 hours H-alpha
  • Camera: SBIG ST-8300M, Temp -20 ° C, Baader LRGB filters, Astrodon 5 nm H-alpha filter
  • Instrument: Meade 25 cm with AstroPhysiscs reducer, focal distance 1750 mm
  • Mount: Losmandy G11
  • Guiding: TS Off Axisguider, Starlight Xpress Lodestar autoguider and PHD
  • Location: Etoile St. Cyrice, France
  • Sky Quality Meter: 21,27
  • Ambient temperature: 15° C
  • Date: 30 august 2011

Image acquisition with ImagesPlus 4.0 Camera Control with dither:
  • 23 Luminance of 10 min, binned 2x2
  • 9 Red + 9 Green + 9 Blue of 5 min, binned 2x2
  • 15 H-alpha of 20 min, binned 2x2
  • 20 Flat fields per channel with Aurora Flatfield panel
  • At home, camera in fridge:
  • 20 Dark frames of 10 min + 20 Dark frames of 5 min
  • 20 Flat darks (per channel) + 20 Bias frames

Processing in ImagesPlus 3.82:
  • Automatic Image Set Processing per channel: calibrate, normalize, grade
  • Align and combine (Min Max Excluded Average)
  • Align and combine Red, Green and Blue results (1:1:1,2)
  • Digital Development (DDP)
  • Reduce High Low Pixel
  • Deconvolution Adaptive Richardson-Lucy (PSF 5x5, 10 iterations)

Processing in Registar:
  • Align Luminance and RGB
  • Align LRGB and H-alpha

Processing in Photoshop CS3:
  • Combine Luminance and RGB with Lab Color (Split RGB and Combine Lum, a, b)
  • Combine H-alpha with LRGB with split channels and paste H-alpha to red channel (Blend Mode Lighten, opacity 40%)
  • Curves
  • Levels
  • Saturation
  • Color Balance
  • Selective Color
  • Noel Carboni's astronomy tools: Star size reduction