18/11/2014
Looking at M33 with the C28 (last night's images, before the clouds closed us down). This is a false color combination of ONE L (luminance) image exposed for 300 sec and ONE H-alpha image exposed for 1200 sec, where the scaled L image representing the continuum was subtracted from the H-alpha one yielding a net-H-alpha image. This was combined into the color composite with the L image, choosing red for L and blue-green for net-H-alpha. Note the much wider distribution of red, corresponding to stars that have left the spiral pattern, and the distribution of the blue-green HII regions that reach quite far from the "red" galaxy...