Patchick 58 in Cassiopeia
Patchick 58 was discovered by the Deep Sky Hunters group in 2013 through a detailed review of sky survey plates. Although it appears to be a planetary nebula, it may be a Stromgren sphere, which is a cloud of ionized hydrogen surrounding a hot blue star or group of stars. The Rosette Nebula, which encloses a cluster of blue stars, is one example of a Stromgren sphere. Pa 58 appears to enclose a pair of 10th magnitude blue stars. This object appears to have an Ha signal only. No OIII signal was detected.
Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn wedge. Dec antibacklash set to 27/27. PEC on.
Exposure: Total exposure time about 13.5 hours; 38 x 20 mins Ha for nebulosity, 10:14:16 x 60 secs RGB for starfield. 8 hours of OIII data revealed no signal, and was not used in the image above. All bin 1x1.
Filters: Astrodon 5nm Ha, 3nm OIII, and Type IIi RGB
Date: Data was collected over 16 nights from August to October 2016.
Imaging automation and capture: Sequence Generator Pro
Guiding Hardware: ASI120MM, Celestron off axis guider. Guiding scale 0.46 arcsec/pixel. 1 second guide exposures.
Focusing: Rigel Systems GCUSB/nStep on stock C11 focuser
Guiding Software: PHD2. RA aggressiveness 55, hysteresis 0, Minimum Move 1.4 arcsecs, Max RA 200, Max Dec 600. Guiding unbinned with ZWO connection. Dec set to hysteresis. Dithering set to Extreme with Settle < 1.2.
Guiding performance: Quite poor, especially August session.
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: 1.2 arcsecs/pixel (50% reduction)
Processing: Bias, darks, and flats. Stacked and processed with PixInsight, with a few minor modifications in Photoshop.