Instrument

12.5" RCOS @  ~f/9 (2880 mm fl) 0.643 arcsec / pixel.  Shown resampled to ~1.4 arcsec/pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ internal filter wheel, AstroDon Filters

Acquisition Data

4/20/2008 to 5/3/2008  Chino Valley... with CCDAutoPilot3 and CCDSoft.

Exposure

LHa(RHa)GB

Ha      540 min. (18 X 30 bin 1x1)

Lum    240 min. (24 x 10 bin 1x1)

RGB    270 min. (9 x 10 bin 2x2) each

Ha data was layered over the Lum and Red channels and blended in using 50% opacity.

Software

CCDSoft, CCDStack, Photoshop CS w/ the Fits Liberator plugin, and Noel Carboni's actions.

CCDStack to register, normalize, data reject, combine and sharpen.

PhotoShop for the color combine.

Comment

North is to the top.
NGC 4631, The Whale Galaxy, is a big beautiful spiral galaxy seen edge-on only 25 million light-years away towards the small northern constellation Canes Venatici. The galaxy is similar in size to our own Milky Way. A companion galaxy, the small elliptical NGC 4627 appears above the Whale Galaxy. Out of view off the lower left corner of the picture lies another distorted galaxy, the hockey stick-shaped NGC 4656. The distortions and mingling trails of gas and dust detected at other wavelengths suggest that all three galaxies have had close encounters with each other in their past. In this image hydrogen alpha filtered data was added to highlight the red HII star forming regions.

Source: NASA APOD