|Here is an image of NGC 891 taken
from the St. Croix
Observatory (SCO). To see a tighter crop of the main galaxy,
click again to return to the wider field image.
The images taken with my Esprit refractor have shown minor pattern noise in the blue channel. The histogram showed that the blue channel was lower than red and green. As I tend to shoot short subs, the blue channel did not have sufficient exposure so this image uses longer sub exposures and the ISO is dropped from 1600 to 800 to maintain star colour. The result is that the pattern noise in the blue channel is gone and the image has a smooth background.