NGC 4631, The 'Whale' galaxy.

This is an edge-on spiral, similar in size to the Milky Way, some 21 million light years away from us.
The small companion elliptical galaxy is NGC 4627.
There is lots of activity in the centre of the 'Whale'…. it's thought that so many supernovae have exploded in this region that gas is being blown out of the plane of the galaxy. This can be seen in X-ray emissions.

This image was taken with 2 cameras, a mono Atik 16HR for luminance and H-alpha, and an OSC 16HRC for the colour data.
I borrowed the OSC camera as I didn't have much time available and wanted to grab the colour data quickly.
While this worked OK on the galaxy itself, the star colours are not correct, and I really noticed the difference here as compared to using coloured filters when it came to processing.
It's not a route I'll be taking again…personally, I prefer mono with filters.

Click on image below for full size version


Telescope. TMB152 @ F8

Cmera. Atik 16HR
L. 20 x 6 minutes
RGB 17 x 5 minutes
Ha 11 x 6 minutes binned 2x2

Ha was added to the red channel in 'LIGHTEN' mode at 50% opacity.

L /Ha imaged on April 1st 2009
RGB imaged on April 27th 2009