NGC 7320
Stephan's Quintet

NGC 7320
Stephan's Quintet:
NGC 7320 is the relatively nearby ("only" ~40 Mly) spiral galaxy along the line of sight towards the much more distant group of galaxies that are about 200 Mly away. The distant group contains NGC 7317, 7318a, 7318b, and 7319. There are also many more much fainter, and much more distant, galaxies visible in the background of this image.

NGC: 7320
Other Catalogs: Hickson Compact Group 92
Right Ascension: 22h 36.0m
Declination: 33° 57'
Apparent Magnitude: 13.2

Date: October 2009
Equipment:
Telescope: Meade 16" Schmidt Cassegrain with f6.3 reducer
Camera: SBIG ST-10XE
Guiding: Meade 5" refractor/DSI Pro/PHD

Exposure:
Total of eight hours with 10 minute sub-frames.
L: 16x10 minutes
R: 11x10 minutes
G: 10x10 minutes
B: 11x10 minutes

Processing Notes: Data acquisition with CCDSoft. Reduced and aligned in CCDStack. Subs combined in Sigma Beta. RGB combined in AstroArt at 1:1:1.5 ratio. Arcsine stretch import of L into Photoshop. Adjusted curves and levels. Slight blur on the dim areas and sharpening on non-star bright areas. ~25% minimum filter on the brighter stars. L was combined with RGB using three layers: Luminance on the bottom; RGB as a multiply(30%); and RGB as a color layer on top. Final stretch and tweak (including fixing "dripping" stars) in Photoshop.
Scale: 1.01

Links to images of this object on other sites:
http://apod.nasa.gov/apod/ap090911.html
http://www.celestronimages.com/details.php?image_id=4214
http://www.noao.edu/outreach/aop/observers/stephan.html

Additional Comments: This was taken over the course of several nights between August and October. The initial August early morning L data had better than typical tracking. All ten 10-minute subframes were used, which is something of a first at this observatory. FWHM was ~3". That image is shown here: http://www.fortlewis.edu/observatory/image_detail.asp?ID=133. An image from 2008 is here: http://www.fortlewis.edu/observatory/image_detail.asp?ID=52. Later imaging nights had tracking issues, especially with most of the color subs. I tried processing with fewer (only the better) color subs, but ended up using most of them, since the background looked better when using more subframes.

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