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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Planetary Nebulae > Abell 74
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Abell 74

PK 72.7-17.1 in Vulpecula

This huge, ghostly planetary nebula is almost pure Ha. I shot several hours of OIII, but found no signal in it when I processed it. The Ha data was colorized in PixInsight and layered onto RGB stars in Photoshop. The galaxy is 15th mag MCG+04-50-004.

Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn Wedge. Dec antibacklash set to 27/27. PEC on.
Cameras: SXVR-H694 (OIII data); QHY8 (OSC RGB data)
Exposure: Total exposure time 11 hours; 30 x 20 mins Ha plus 20 x 2 mins each RGB. All bin 1x1.
Filters: Astrodon 5nm Ha and Type IIi RGB
Date: Data was collected over 4 nights in September 2015
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. RA aggressiveness 55, hysteresis 0, Minimum Move 1.4 arcsecs, Max RA 1000, Max Dec 600. Guiding unbinned with ZWO connection. Dec set to hysteresis. Dithering set to Extreme with Settle < 1.2.
Guiding performance: FWHM of subs about 1.2 arc seconds, RMS in PHD about 0.75 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: 1.2 arcsecs/pixel
Processing: Bias, darks, and flats. Stacked and processed with PixInsight, with a few minor modifications in Photoshop. Ha and RGB merge in Photoshop.

other sizes: small medium large original auto
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