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Questions tagged [radio-telescope]

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How did Arecibo make radar images of ice on Mercury's poles?

How did Arecibo make radar images of ice on Mercury's poles? How were observations of the poles of Mercury geometrically possible from Earth? How was "high-resolution (1.5-km) imaging" possible from ...
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1answer
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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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How do astronomers convert radio signals received by their antenna to images?

I'm very new to radio astronomy and I am curious how an the signals received by a radio antenna are converted to data on a computer and then images? Is there a popular software to use for this, or do ...
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1answer
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What determines the surface material of the ALMA and Spitzer telescope?

The transition between metal dish and mirror happens around hundreds of microns. For example, the shortest wavelength the ALMA(metal dish) can detect is about 0.3mm, while the longest wavelength the ...
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1answer
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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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3answers
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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 ...
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143 views

Event Horizon Telescope Data Cleanup

I was wondering how the researchers were able to minimize or neutralize confirmation bias regarding the data collected? As I understand it, the algorithm pruned much of the data, which would make ...
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1answer
141 views

Does the “photo of a black hole” taken by EHT actually depict a visible light-based scenario?

I'm still at my bachelor of electronic and communications engineering, so I'm not an expert of radiotelescopes; however, I surely know that, typically, radio communications are characterized by a RX ...
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197 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 ...
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3answers
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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 ...
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1answer
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Why did the Event Horizon Telescope take so long to take a photo of a black hole?

The Event Horizon Telescope is in the news now because they are about to release the first ever picture of a black hole. They have been working on this since 2006. Why did it take 13 years to produce ...
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1answer
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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 ...
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1answer
60 views

Tuning radio telescopes

In this paper, Section 2.1, the authors talk about using the ICRF2 to find a tuning frequency in search of the 21-cm absorption (of HI). Since we already know the frequency of HI (1420.40575177 MHz), ...
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1answer
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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 ...
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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-...
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1answer
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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 ...
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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 ...
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1answer
53 views

What telescope might this be a model of, with Sir Fred Hoyle?

The BBC article Archaeopteryx: The day the fossil feathers flew has nothing to do with Astronomy but it shows a file photo of the famous astronomer Sir Fred Hoyle with a model of what looks like some ...
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Does Arecibo's secondary optics compensate aberrations when viewing farther away from vertical?

In the beginning of the short YouTube video Arecibo Uncut: Under the Dish with Phil Perillat it is mentioned that while dish antennas are usually a parabola, the problem is that a static parabola ...
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Please dsescribe how this instrument works [closed]

Describe how this instrument works:
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Can I sense a bright star pointing an eight foot antenna towards it?

If I connect an eight foot Yagi or other comparable sized antenna to my oscilloscope and point the antenna at a bright star will I see a voltage on my oscilloscope? I am not interested in turning the ...
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1answer
68 views

Is it possible to see an image with radio telescope of something not so far away in detail?

Can an image of a person using a radio telescope see a person from far away? Could a radio telescope be made to see someone walking on Mars? https://space.stackexchange.com/questions/30477/could-we-...
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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 ...
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2answers
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How to calculate the integrated source flux density of a continuous source?

I'm working with data from radio surveys. My images are .fits files with BUNIT Jy/beam. I want to calculate the net flux from a continuous source (not point source). When I simply added all the ...
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223 views

how much further can a radio telescope than an optical telescope

I know that radio telescope can 'see'* further than an optical telescope but I would like to know how much further? (let's say the optical has a magnification of 50x and the radio has a dish of 90m in ...
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1answer
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How do ASKAP's focal plane phased array feeds interact with the entire array phasing?

Sky & Telescope's ASKAP Joins the Hunt for Mysterious Bursts says: A new telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), has joined the search for energetic and elusive ...
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How to find period of a pulsar from a given time sampled voltage data?

I've a data file with 2 columns, each containing time sampled voltage output (a sequence of real numbers) from a radio telescope, so there is a pair of telescope which are measuring the signal here. ...
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3answers
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Can radio-based telescopes produce visible light images?

It's a fairly simple question (at least in my layman's mind). Can a radio telescope that has no mirrors or lenses to capture visible light (to human eyes) still produce imagery like an optical ...
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260 views

Radiometer Equation for Flux Density

In Duncan and Lorimer's Handbook of Pulsar Astronomy, the equation for the flux density using a radio telescope is given as (for a top-hat function): $$S=\frac{\beta\,\mathrm{SNR}\, T_{sys}}{G\sqrt{...
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2answers
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How do astronomers at SETI know if they received intelligent radio signals from other planets?

Do they expect to see wave modulations like the ones we use in our technology? what do they expect the waves to be like exactly?
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Can any radio telescope be hooked up with the Very Long Baseline Array, or other interferometers?

The Very Long Baseline Array uses both Arecibo and Spectr-R, the world's largest space telescope with 10 m diameter at Lunar distance, as well as many other antennas. Are there any particular ...
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176 views

Can radio telescopes such as arecibo image the subsurface of asteroids or planets?

This was done with the moon: Radio Dishes Peer Beneath Moon's Surface
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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 ...
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Help With Transit Radio Telescope Data Analysis

My high school teacher and I recently built a 10 ft. mesh dish transit radio telescope. In order to compete this year at Nationals for our science fair, we came up with the idea of using a bluetooth ...
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1answer
98 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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194 views

What is a radio “homology telescope” and is the 500m dish in China one?

This question is about design aspects of large radio telescope dishes which allow them to flex under the influence of gravity as they change elevation angle, and still maintain good optical ...
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1answer
184 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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1answer
198 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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570 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 ...