Omega Centauri

No doubt about it – the largest, most massive and most glorious Milky Way globular cluster in the entire sky is Omega Centauri!

It is a whopper, containing about 10 million stars and a total of 4 million solar masses. It is even visible to the naked eye as a faint fuzzball about the size of the Moon if you know where to look.

Omega Centauri is technically visible from a latitude as far north as 40° N but here in the Southern Hemisphere, it is easily visible for much of the year, as is the almost as impressive 47-Tucanae, which is even further South.

I’ve imaged this stunning object several times before but this is the first time using the ZWO ASI071 camera and I was doing ok – until the Moon rose.

Object Details:

Designation: Caldwell 80, NGC 5139.
Constellation: Centaurus.
Visual magnitude:  +3.7
Apparent size:  55′
Diameter:  271 light years.
Distance:   17,000 light years.
Altitude:   67° above SE horizon.


Exposure:  14.75 min. (10 frames @ 88.5 sec).
Gain:  152.
Date:  2019-06-22.
Location:  The Oaks, NSW, semi-dark rural.
Conditions:  clear.
Moon: rose at 9.22 pm. imaging ceased 9.27 pm.
Sky:  0.50 e/pixel/s.


Image acquisition software:  SharpCap, live stacked.
Image post-processing:  GIMP.
Cropping:   two edges, to centre the object.


Telescope: SkyWatcher Esprit  Type: 120ED triplet refractor
Focal: 840 mm F/7 Mount: SkyWatcher EQ6-R Pro
Camera: ZWO ASI 071 MC Pro Type: CMOS 28.4mm 16 Mpx
Optical aids: Flattener: Y; filter: N Guiding: No
Polar aligning: QHYCCD PoleMaster Polar Error: 04’ 50”

Previous images Of Omega Centauri: 

2015-03-27  |   2016-04-27  |  2016-06-06  |  2017-07-06

Geek Log:

[ZWO ASI071MC Pro]
Debayer Preview=On
Output Format=FITS files (*.fits)
Capture Area=4944×3284
Colour Space=RAW16
Hardware Binning=Off
Turbo USB=40
Frame Rate Limit=Maximum
Timestamp Frames=Off
White Bal (B)=50
White Bal (R)=53
Cooler Power=100
Target Temperature=-15
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Anti Dew Heater=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.5
#White Point
Display White Point=1


Image © Roger Powell



  1. Really nice. It reminds me of a favorite of mine in Hercules M-13. Wouldn’t it be an amazing sight from within one of those clusters?


  2. Indeed, those stars are packed very close. I’m not sure if any potential planetary orbits could be stable in those conditions but it might negate the need for street lighting – and what a great view of the Milky Way from that vantage point!


  3. It’s hard to spot from the northern hemisphere unless the horizon has almost no haze and there’s no ambient light in that direction.

    From Southern California, April through May is your window.


    1. Anthony, that’s almost the same problem we have seeing M31.
      I want the Earth’s axial tilt to wobble more quickly….
      Thanks for your comment, I hope you get to see it!


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