Centaurus A

Designation:  NGC 5128, Caldwell 77; in Centaurus.
Visual magnitude:    +6.6
Apparent size: 26 x 20 arc-minutes.
Diameter: 90,300 light years.
Distance: 12 million light years.

I had several goes at processing this before I got what seems to be the best out of my two hour exposure.

Centaurus A is a unique nearby “peculiar” galaxy, with a very impressive dust lane which is seemingly superimposed on an elliptical galaxy.

It is a magnificent object in the southern sky and astronomers seem to believe it is actually two colliding galaxies.

The bulge consists mostly of evolved red stars, whilst in contrast, the dust lane shows evidence of recent new star formation.

Centaurus A is also known as an active galaxy, with large radio telescopes revealing two huge galactic polar emission jets moving at relativistic speeds (from a super-massive black hole at the core with a mass of 55 million solar masses ) and creating huge lobes extending for hundreds of light years.

No mention of Covid-19 in this post. It’s doing my head in – but something else is cheesing me off too.

The lighting from the excessively bright street light (not very thoughtfully whacked up recently by the kind folks from my local council) was not only blinding me if I looked up at it – but it affected some of my images by shining directly onto the optical tube of my telescope. 😵

It’s dangerous to wear sun glasses at night but I might have to try wearing a cap – and to protect my hobby I had to reduce the actual detrimental effect it had on my nocturnal photographic work.

So I had to come up with a cunning and highly technical plan.

My equipment setup is shown, at the end of session, by flashlight below – complete with telescope, work station and (behind) my new technical masterpiece.

It’s a timber pole with a masonite sheet attached. It looks a bit like a basketball practice rig – without the ring.

I call it my Universal Street-lighting Over-brightness Defence Shield….

…..or USODS for short.


Featured Image Details
Date:  2020-03-20Exposure: 41 x 176s = 120 min.
Sky brightness (e/px/s): 0.64Gain setting:  61
Camera: ZWO ASI 071 MC ProType: CMOS 28.4mm 16 Mpx
Location:  outer suburban.Conditions:  clear sky, no Moon

My images are captured with Sharpcap-pro software using the live-stacking feature, with in-field image processing, including dark and flat image subtraction. Image post-processing is carried out using GIMP freeware.

The image was cropped and I had it annotated by Astrometry.net

Telescope Details
SkyWatcher Esprit 120 mm apochromatic 3-element refractor.
840 mm focal length @ f/7 with field flattener.
Baader L-Booster UHC-S light pollution filter 2458276.
SkyWatcher EQ6-R Pro mount, with a polar error of 00′ 03″
ZWO ASI120 guide camera, using PHD2 software.
QHYCCD PoleMaster polar aligning camera.
2018-03-10 Telescope & Roger
Images © Roger Powell
I’m a founder member of Macarthur Astronomical Society. 🙃
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=80(Auto)
Frame Rate Limit=Maximum
Timestamp Frames=Off
White Bal (B)=99
White Bal (R)=60
Anti Dew Heater=On
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
Banding Threshold=35
Banding Suppression=0
Apply Flat=C:\Users\powel\Desktop\SharpCap Captures\2020-02-27\Capture\flats\20_05_07_offset=0.054%.png
Subtract Dark=C:\Users\powel\Desktop\SharpCap Captures\darks\ZWO ASI071MC Pro\RAW16@4944×3284\176.2s\gain_61\dark_5_frames_-5.8C_2020-03-20T10_55_31.png
Black Point
Display Black Point=0
MidTone Point
Display MidTone Point=0.5
White Point
Display White Point=1


  1. Boggling to think of colliding galaxies and emissions hundreds of light years in length.

    Best I can manage is a moderately-sized room.

    . . . have you tried getting funding for your USODS? An appearance on Shark Tank, maybe?

    Liked by 1 person

  2. KUDOS on the USODS You are a creative fellow.

    Last week I hoped to get a view and shot of the Moon-Mars-Jupiter grouping. No such luck and the clouds just won’t go away. Today there is a threat of a little snow later. Two episodes of rain are in the week forecast. This too shall pass. Meanwhile, I get to admire your work. Keep em coming.

    Liked by 1 person

    1. Thanks, Jim.
      Over the next couple of months keep an eye out for comet C/2019 Y4 (ATLAS), which is a candidate for naked eye viewing in a few months time. Currently in Ursa Major, well beyond my grasp.


  3. Yes, light pollution just seems to get worse all the time. At least you managed an amazing image. I can actually imagine the band in the middle is the edge of the two galaxies as they wind around each other.

    Liked by 1 person

    1. Thanks very much for commenting, Tony.
      I know you’ve told me how bad the local lighting is for you but you may soon find that becoming your last option.


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