Questions tagged [radio-telescope]

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1answer
214 views

What is the highest granularity focal-plane array on a dish radio telescope? Or is this the ONLY ONE?

There is a short Wikipedia article Focal Plane Arrays that enumerates some projects, but my question is more along the lines of what is (at least) nearly complete or in "first light" phase, even if ...
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1answer
207 views

How did single dish (or single receiver) radio telescopes originally generate images?

That actually sums up my question nicely: How did single dish (or single receiver) radio telescopes originally generate images? - or at least 2D intensity maps or contour plots. Early radio ...
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7answers
651 views

Radio telescope targeting

How do you target a radio telescope on the precise object you wish to observe? You can point it in the general direction but how do you get the information from the exact point in the sky that you are ...
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1answer
105 views

Which 16 antenna locations were used this MeerKAT radio image?

The final configuration of the MeerKAT radio array will be 64 dishes. In the press release of July 16, 2016 a radio image is shown using a completed sub-set of 16 dishes. Which 16 are these? I can ...
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0answers
44 views

How does ALMA produce stable, mutually coherent ~THz local oscillators for all of their dishes?

The ALMA (Atacama Large Millimetre/submillimetre Array) radio telescope's band-10 capabaility is now operational, per this answer. That's confirmed by NRAO's First Science with ALMA’s Highest-...
6
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2answers
432 views

Amateur radioastronomy: dish suggestions

What kind of amateur radioastronomy can any interested citized do with: a) A 2 m dish antenna. b) A 2,5 m antenna. c) A 3 m antenna. d) A 5 m antenna. e) A >5 m <10 m antenna (likely I can not ...
5
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3answers
231 views

How can the Event Horizon Telescope image Sgr A* when it's not visible from all sites at one time?

I went to https://eventhorizontelescope.org/array and read about the ten sites listed as part of the EHT, I have a mashed-up screen shot of them below. I made a little script also shown below with ...
7
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3answers
350 views

Why are the ALMA receivers' ADCs only 3-bits?

above: Table 1 from Performance Highlights of the ALMA Correlators The ALMA receivers use 3-bit ADCs for what would seem to be to be a high dynamic range application needing much finer quantization ...
7
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3answers
658 views

Why does the Event Horizon Telescope (EHT) not include telescopes from Africa, Asia or Australia?

The Event Horizon Telescope seems to include these radio telescopes currently: Image by European Southern Observatory (ESO)/O. Furtak; CC-BY 4.0-licensed, see the source on Wikipedia Commons and the ...
5
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2answers
263 views

What part of the EM spectrum was used in the black hole image?

The EHT has published the first image of a black hole. It is the event horizon of the singularity in M87 against its accretion disk. I've been through the reports in the popular press but none ...
3
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1answer
160 views

Will the SKA's total bandwidth still exceed the Earth's internet's bandwidth?

In the early 2010's there were many popular articles that said that the total bandwidth of the the Square Kilometer Array's optical fiber network for raw data from each dish would be larger than the ...
3
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1answer
44 views

Why would atmospheric absorption increase rather than decrease the antenna temperature in Penzias and Wilson's famous CMB observation?

The classic paper A MEASUREMENT OF EXCESS ANTENNA TEMPERATURE AT 4080 Mc/s begins: Measurements of the effective zenith noise temperature of the 20-foot horn-reflector antenna (Crawford, Hogg, and ...
2
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1answer
62 views

What might some examples be of radio telescope interferometric arrays made from “cheap components relying on massive computing power”?

This answer mentions that there are some interferometric radio telescope arrays ...consisting of very cheap components relying on massive computing power to retrieve the signals from noise... The ...
2
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0answers
50 views

Feasibility of radioastronomy in densely populated areas

In general, radioastronomy as well as optical astronomy depend on a good SNR. This meant to position telescopes as far as possible from noise sources. Optical telescopes were built at elevated points ...
2
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1answer
49 views

How do radio telescopes gather information about visible light?

Is the first image of a black hole that was captured by the Event Horizon Telescope what would be seen with a large enough optical telescope (or with the naked eye from a proper distance of the black ...
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1answer
25 views

Need some sources on radiotelescope sensitivity

Could anyone direct me to papers with info on minimal flux that can be registered with radiotelescopes?
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41 views

How does Canada's radiotelescope CHIME manage polarization-dependent apodization of the fast f/0.25 optics?

CHIME, the Canadian Hydrogen Intensity Mapping Experiment uses four parabolic cylinder reflectors and a dense linear array of 256 x 2 polarization feeds along each focal line. Each feed is a dual ...
0
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1answer
44 views

How often do they move most/all of ALMA's dishes?

The Phys.org article Unknown treasure trove of planets found hiding in dust reports on recently published radio measurements (~1.3mm) of planetary systems forming around stars in Taurus: Scientists ...