The Dumbbell Nebula in Vulpecula
Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn Wedge. Dec antibacklash set to 27/27. PEC on.
Exposure: 65 x 2 minutes luminance, bin 1x1; 30x2:17x2:20x2 RGB, bin 2x2
Date: June 26-27, 2012
Conditions: Seeing 3/5 (3.2 arcsecs). Transparency 3/5.
Image scale at capture: 0.6 arcsecs/pixel = f/5.5
Guiding Hardware: Flea 3, Taurus Tracker III off axis guider. Guiding scale 0.72 arcsec/pixel. 1 second guide exposures.
Guiding Software: PHD. Aggressiveness 80, Hysteresis 0, Minimum Move 0.9, Max RA 1000, Max Dec 600. Dec set to auto/resist switching. Dithering set to Extreme with Settle < 1.2. Calibration steps 8 x 9.
Guiding performance: FWHM of subs = 3.1 arc seconds. RMS 0.50 arc seconds, OSC 0.31.
Light pollution: Bortle 8 (white zone, NELM about mag 4.5)
Filters: Astronomik 2c LRGB
Scale of presentation: 1.2 arcsecs/pixel (50%)
Capture software: Sequence Generator Pro 2.0.22; controlled remotely with TeamViewer.
Processing: Bad pixel map in Nebulosity 2, stacked with Deep Sky Stacker, post-processed with Photoshop CS2.
Focus was less than perfect on some of the luminance frames, resulting in a bit of elongation that was removed with less than complete success using an offset filter in Photoshop.