This is M33, a neighbouring spiral galaxy which is the third largest in our Local Group and only slightly further than the Andromeda Galaxy M31.
M33 is estimated to contain up to about forty billion stars.
Messier 33, NGC 598, UGC 1117, PGC 5818, MCG 5-4-69, CGCG 502-110.
Visual magnitude: +5.8
Apparent diameter: 62 x 36 arc-min. (about 2 Lunar Diameter).
Actual diameter: 50,000 light years (about half our Milky Way diameter).
Distance: 2,800,000 light years.
Altitude: 24° above Northern Horizon.
Exposure: 16 x 4 min, ISO 1600 (+ 6 dark, 20 bias).
Location: Field night at The Oaks, NSW, with Macarthur Astronomical Society
Sky: semi-dark rural with metropolitan sky-glow between East and North.
Cloud: mostly clear, some minor high cloud interference.
Processing: Canon DPP > Deep Sky Stacker > GIMP.
Imaging telescope: Skywatcher Esprit 120ED Super APO triplet refractor.
Focal length: 840 mm, focal ratio: f/7.
Imaging camera: Canon EOS 60D.
Guiding camera: Orion StarShoot.
Guiding control software: PHD2.
Guiding accuracy: 1″ rms approx.
Telescope mount: SkyWatcher EQ6-R.
Polar aligning: QHYCCD PoleMaster.
Field flattener: yes; filter: no.
Image © R.Powell