An open star cluster in Sagittarius.
Object Details:
Messier 23, NGC 6494
Visual magnitude: +5.5
Apparent diameter: 29 arc-min.
Actual diameter: 17.3 light years.
Distance: 2000 light years.
Image:
Exposure: 10 x 2 min ISO 800.
Date: 2017-09-09.
Location: Leumeah, NSW.
Sky: outer suburban sky, some thin high cloud.
Processing: Canon DPP, Deep Sky Stacker and GIMP.
Cropping: no.
Gear:
Imaging telescope: Skywatcher Esprit 120ED Super APO triplet refractor.
Focal length: 840 mm, focal ratio: f/7.
Imaging camera: Canon EOS 60D.
Guiding telescope: Orion ShortTube 80mm Achromatic doublet.
Focal length: 400 mm, focal ratio: f/5.
Guiding camera: Orion StarShoot camera.
Guiding control software: PHD2.
Telescope mount: SkyWatcher EQ6-R.
Polar aligning: QHYCCD PoleMaster.
Flattener, no filter.
Image © R.Powell
Cosmic Focus 