The famous galaxy NGC 253, brightest member of the southern Sculptor group. With a visual magnitude of 8.0, it is appears as a long, oval bulge and mottled disk, some 25' x 7' min size (true size of some 70,000 light years across), with complex dust lanes north of the core. It is part of a group of galaxies located 11.4 million light years from the Milky Way, and is viewed by us almost side on spiral (Sc type), giving it the shape of a coin. There is intense starburst activity in its outer arms, and some prominent HII regions, whereas the core is older and redder with a 5 million solar mass black hole at its centre.
The image was captured from my Adelaide surburban backyard, using an Orion ED80T CT apo astrograph (at f/4.8), mounted on an AZ-EQ6. The CCD camera was an Orion StarShoot G3 mono, guided with PHD2 using a think OAG and an ASI120MM-S guide camera. Not much more I can get out of this setup -- it is quite undersampled (4.6 arcsec/pixel), and not ideal for smaller DSOs like this!
The image is composed of the following:
Lum = 62 x 5 min
Ha = 15 x 10 min
R, G & B = 52 x 5 min for each channel
After rejections, this led to a total integration time of 20.7 hours.
I used a synthetic luminance channel by blending an exposure-based weighting of the L, Ha, R, G and B luminances. All subs were unbinned.
Captured over the period 24 Aug to 2 Sept 2014, as weather permitted. Pre-processed with flats (light box), bad pixel map (based on 70 darks) and bias in Nebulosity. Aligned and Drizzled in DSS. Post-processed in StarTools.
Full capture/processing details and higher rez version here:
http://www.astrobin.com/118924/