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.

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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.

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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.

👁👁
👅

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Featured Image Details

Date:  2020-03-20	Exposure: 41 x 176s = 120 min.
Sky brightness (e/px/s): 0.64	Gain setting:  61
Camera: ZWO ASI 071 MC Pro	Type: 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

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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.

Images © Roger Powell
I’m a founder member of Macarthur Astronomical Society. 🙃

Geek Log

[ZWO ASI071MC Pro] Debayer Preview=On Pan=0 Tilt=0 Output Format=FITS files (*.fits) Binning=1 Capture Area=4944×3284 Colour Space=RAW16 Hardware Binning=Off Turbo USB=80(Auto) Flip=None Frame Rate Limit=Maximum Gain=61 Exposure=176.189728 Timestamp Frames=Off White Bal (B)=99 White Bal (R)=60 Brightness=12 Anti Dew Heater=On Temperature=-9.4 Cooler Power=100 Target Temperature=-15 Cooler=On

Auto Exp Max Gain=300 Auto Exp Max Exp M S=30000 Auto Exp Target Brightness=100Mono 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 TimeStamp=2020-03-20T13:08:52.3150169Z SharpCapVersion=3.2.6248.0 TotalExposure(s)=7223.778848 StackedFrames=41

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