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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Galaxies > NGC 4631
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NGC 4631

The Whale Galaxy in Canes Venatici

Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn Wedge. Dec antibacklash set to 27/27. PEC on.
Camera: SXVR-H694
Exposure: 364 minutes total, LRGB 144:48:54:68, all 2 minute exposures.
Filters: Astrodon Type IIi LRGB
Date: 7 nights from March 22 to May 8, 2014

Imaging automation and capture: Sequence Generator Pro

Guiding Hardware: ASI120MM, Celestron off axis guider. Guiding scale 0.94 arcsec/pixel. 1 second guide exposures.
Focusing: Rigel Systems GCUSB/nStep on stock C11 focuser
Guiding Software: PHD. Aggressiveness 80, Hysteresis 0, Minimum Move 0.7, Max RA 200, 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.
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: Bad pixel mapping, bias, and flats. Bad pixel maps with Nebulosity 2, stacked with Deep Sky Stacker, post-processed with Photoshop CS2.

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