PK 138+2.1 in Cassiopeia
This is an Ha/OIII/OIII image. Seeing was usually slightly above average for these images. Transparency was about average.
Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn Wedge. Dec antibacklash set to 27/27. PEC on.
Exposure: 13.3 hours total. 22 x 20 mins Ha, 18 x 20 min OIII, both bin 1x1.
Filters: Astrodon 5nm Ha and 3nm OIII
Date: OIII was collected over three nights in August and Septembr 2014, Ha was collected over five nights in October and November 2014.
Imaging automation and capture: Sequence Generator Pro
Guiding Hardware: ASI120MM, Celestron off axis guider. Guiding scale 0.92 arcsec/pixel. 1 second guide exposures.
Focusing: Rigel Systems GCUSB/nStep on stock C11 focuser
Guiding Software: PHD2. Aggressiveness 80, Hysteresis 0, Minimum Move 0.7, Max RA 1000, Max Dec 600. Dec set to hysteresis. Dithering set to Extreme with Settle < 1.2.
Guiding performance: HFR of subs about 1.2 arc seconds, RMS in PHD about 0.7 arcsecs.
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: Bias, darks, and flats. Stacked with Deep Sky Stacker, post-processed with Photoshop, with some deconvolution using the AstraImage PS plugin.