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This is a Blog on relativity and cosmology for engineers and the like. My website "Relativity-4-Engineers" has more in-depth stuff.

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SKA shared between Africa and Australia

Posted May 29, 2012 8:00 AM by Jorrie

"25 May 2012, Amsterdam, the Netherlands - The Members of the SKA Organisation today agreed on a dual site solution for the Square Kilometre Array telescope, a crucial step towards building the world's largest and most sensitive radio telescope.

The ASKAP and MeerKAT precursor dishes will be incorporated into Phase I of the SKA which will deliver more science and will maximise on investments already made by both Australia and South Africa."

This agreement was reached by the Members of the SKA Organization who did not bid to host the SKA (Canada, China, Italy, the Netherlands and the United Kingdom). The Office of the SKA Organization (in the UK) will now lead a detailed definition period to clarify the implementation.

Photo: KAT-7 precursor array (7 dish), operational in South Africa.[1]

So what is the SKA supposed to be?

In brief it is a system of three different antenna types (frequency bands), packed into clusters, which are then spread out over a considerable area. The total RF collecting area is planned to be about a square km, with the original maximum baseline about 3000 km. With the decision to split the system between Africa and Australia, the baseline could now potentially increase to some 9000 km, at least for some observations.

The preliminary frequency ranges are: 70 to 200 MHz (low), 200 to 450 Mhz (mid) and 0.45 to 10 GHz (dishes)[2]. These ranges are nothing new in radio astronomy, but the resolution and baseline are ground-breaking for the frequency range.

What do we hope to achieve?

For me the most exiting prospect is that the period between 300 thousand years and 500 million years after T0 may become resolvable. This is from the horizon of the observable cosmos to the formation of the first stars and galaxies, an epoch where many new insights may lurk.

The improved performance will obviously refine many previous observations and hence make it possible to constrain (or even rule out) various models. Dark matter, dark energy, cosmic magnetism and gravitational waves (GWs)[3] will be under close scrutiny.

Some speculative potential findings include extra terrestrial life and intelligence. We may perhaps find ET phoning us, here at home...

-J

[1] http://www.ska.ac.za/ ; http://www.skatelescope.org/

[2] 0.45 to 2 GHz in phase 1, up to 10 GHz or more in phase 2.

[3] The SKA will not directly detect GWs, but will be able to find and observe binary pulsars more accurately, thus enabling tests of General Relativity's prediction of the loss of orbital energy to higher precision. In some sense, the SKA plus a binary pulsar is a gigantic GW detector.

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#1

Re: SKA shared between Africa and Australia

05/29/2012 11:55 PM

Splitting the project is an odd decision given that Oz has a vanishingly low population density (near the center of the site), stable government, rule of law, a national optical broadband system being rolled out and a large science/technology infrastructure.

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#2
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Re: SKA shared between Africa and Australia

05/30/2012 1:36 AM

If the project has not been split, the decision would probably have gone to Africa. This is what the Site Selection Advisory Committee recommended earlier.

I think sense has prevailed; the significant investments already made by Oz and SA are now fully utilized. Actually, according to the Site Options Working Group* final report, phase 1 of the project will now deliver more science than specified (for phase 1) without any increase in cost.

-J

* Check under Project Documents

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#3
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Re: SKA shared between Africa and Australia

05/30/2012 5:49 AM

Do you have any idea who the prime contractor for the build in Oz will be mate?

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Re: SKA shared between Africa and Australia

05/31/2012 7:41 AM

I have it on good authority it will be Bazza, Gazza and their mate Bill. If the equal opportunity mob get on their backs they will have to have some new departments added so that the head of said departments can be sheilas of various ethnicities.

Then the unions will demand that Aussie workers be given a fair suck of the sauce bottle before letting people from O.S. come in willy nilly.

Let me tell you if Bazza cuts corners like he usually does the first cock eyed bob that tears through will flatten them all.

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#5
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Re: SKA shared between Africa and Australia

05/31/2012 8:52 AM

I hear you on the EEO bit.

Just because I'm not located in Oz don't assume I'm from OS.

We get about you know. There are ethnic Australians of diverse antecedence living everywhere these days.

I live in the electorate of The Australian Diaspora.... if you get my drift.

I'm heading south soon and on the scent for possible gainful and interesting employment.

Seriously mate...these things can be designed and built to be very, very cyclone proof.

I've never seen one that's been wrinkled let alone flattened by the weather.

So have you got Bazza's number mate?

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#8
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Re: SKA shared between Africa and Australia

05/31/2012 10:15 AM

Seems like you're the only one what cops the lingo.

Goodonya.

What area are you looking for employment in?

What task would you like to do?

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#10
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Re: SKA shared between Africa and Australia

05/31/2012 11:53 AM

Implementation of RF systems et al is my thing.

The reference provided by Jorrie has a very comprehensive listing of all or most of the roles.

More reading ahead.

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#11
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Re: SKA shared between Africa and Australia

06/01/2012 6:03 AM

Sorry, i can offer no help there. My brother in law has a business that supplied the codecs for most of the media teams that were here for the Sydney olympics but he has recently had to downsize and sell off the property he bought in preparation to expand. Lets hope the SKA gets things moving again.

Jim

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#6

Re: SKA shared between Africa and Australia

05/31/2012 9:02 AM

Thanks for that Jorrie.

Do you have any idea about the timeline for this project?

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#7
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Re: SKA shared between Africa and Australia

05/31/2012 10:05 AM

SKA timeline according to http://www.skatelescope.org/uploaded/38221_SKA_Project_Execution_Plan.pdf:

phase 1: 2018, phase 2: 2022, full performance: 2024

-J

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Re: SKA shared between Africa and Australia

05/31/2012 11:49 AM

So, according to that great reference, construction start for SKA1 is 2016 and SKA2 is 2018.

I'll have to find something else to do till that starts or find a design role...

Plenty of good reading there Jorrie. Thanks.

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#12

Re: SKA shared between Africa and Australia

06/01/2012 2:17 PM

Thanks for this article.

I'm an electronic engineer and I'm very interested in understanding the methods used to make such a telescope. Of course the phased arrival of an EM wave at multiple receivers can be used (with extremely careful timing) to reconstruct properties of the emitter. But I have never seen a detailed explanation of the "how" its actually done and how its specifically done on such an large array.

For instance how are the individual antenna calibrated (for relative intensity measures, for time delays to/from the computers - which I presume could even be variable with temperature / time of day ! ) so that computers can reconstruct the image? How are they used across continents ?? How are the details of spacial images (like diffuse clouds of gas for instance) rather than simple point emitters (distant stars) reconstructed from the array?

If there's a good source of papers or information on this I'd appreciate it. I don't need spoon feeding :-) just pointing to the kitchen :-)

thanks

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#13
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Re: SKA shared between Africa and Australia

06/01/2012 2:50 PM

Hi ss3e55, I think the secret lurks in calibration, calibration, calibration...

And of course data time-stamping with local, synchronized atomic clocks. This Wiki article gives some good information and references: http://en.wikipedia.org/wiki/Very_Long_Baseline_Interferometry

-J

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Re: SKA shared between Africa and Australia

06/01/2012 4:14 PM

thanks Jorrie, this is a good start and the wiki leads onwards to more articles...it might be a while but I can see the start of my understanding.

Of course the accuracy is highly dependent on the atomic clocks used to timestamp the signals. I can also see that systematic errors (or periodic ones due to cooling down of antennae from the Sun going below the horizon for instance) can be eliminated by careful recording of a well known standard source (recorded simultaneously on all receivers)...but some of the steps to reconstitute full images are still tough to understand.

For instance at first I presumed each antenna's signal becomes a single pixel in that image, but that implies being able to point each antenna separately to the most minutely fine tuned angle differences , whereas as I think about it now, I think an image might be built by steering the "entire" array and sampling (because only the array as a whole as a fine enough beam resolution needed to resolve a single pixel)? Perhaps the earth's drift and rotation are used to help "scan" a line of pixels...with a flyback and reposition for another line...who knows? :-)

Well thanks for the first steps...I'll see how far my curiosity takes me :-)

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