The Eta Carinae Nebula – a bright nebula visible to the naked eye in the Southern Hemisphere sky. It is even bigger and brighter than the much more celebrated Orion Nebula.
NGC 3372, Caldwell 92, Keyhole Nebula.
Visual magnitude: +1.0
Apparent diameter: 120 x 120 arc-min. (about 4×4 Lunar Diameters).
Actual diameter: 350 light years.
Distance: 10,000 light years.
Altitude: 36° above Southern Horizon.
Exposure: 17 x 1 min, ISO 4000 (+ 6 dark, 4 bias).
Location: Field night at The Oaks, NSW, with Macarthur Astronomical Society
Sky: semi-dark rural with metropolitan sky-glow between East and North.
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: 0.9″ rms approx.
Telescope mount: SkyWatcher EQ6-R.
Polar aligning: QHYCCD PoleMaster.
Polar alignment error: 11 arc-min.
Field flattener: yes; filter: no.
This image would have benefited from a much longer total exposure and might also have improved with a lower ISO setting.
Image © R.Powell