NGC 6781 Planetary Nebula in Aquila
This is a bicolor Ha/OIII image, with a synthetic green layer. Crops of the separate H-alpha and OIII channels can be seen here.
Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn Wedge. Dec antibacklash set to 27/27. PEC on.
Exposure: 10hr 50min total, 32x10 mins Ha, 33x10mins OIII, bin 1x1
Filters: Astrodon 5nm Ha, 3nm OIII
Date: 4 nights from July 6 to July 17, 2013
Imaging automation and capture: Sequence Generator Pro
Guiding Hardware: Flea3, 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.
Guiding performance: HFR of subs about 1.2 arc seconds, RMS in PHD about 0.5 arcsecs.
Focusing: Rigel Systems GCUSB/nStep on stock C11 focuser
Light pollution: Bortle 8 (white zone, NELM about mag 4.5)
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 0.6 arcsecs/pixel
Processing: Bad pixel map in Nebulosity 2, stacked with Deep Sky Stacker, post-processed with Photoshop CS2.