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39 votes
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Why are radio telescopes often built into natural depressions?

Depressions are ideal for extremely large single-dish telescopes like Arecibo and FAST for several reasons, but the single greatest advantage is structural. These instruments are several hundred ...
HDE 226868's user avatar
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36 votes
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What will succeed the Arecibo Observatory?

There's no simple answer. In the immediate future, different radio telescopes around the world will pick up the slack in various ways; how that happens will depend on the needs of individual observers ...
HDE 226868's user avatar
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36 votes

Is there any role today that would justify building a large single dish radio telescope to replace Arecibo?

Arecibo wasn't just a radio telescope, it was a radar telescope, bouncing megawatt-level radio signals off various bodies in the Solar System. A single-dish transmitter is far superior to a phased-...
Mark's user avatar
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31 votes
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Could we carve a large radio dish in the Antarctic ice?

Great question! There are many open and active antarctic permanent bases and several antarctic astronomical observatories. There are even major large projects that involve substantial drilling and ...
uhoh's user avatar
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29 votes
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Can I sense a bright star pointing an eight foot antenna towards it?

Stars are too dim for amateur radio equipment. There are two possible radio sources that you can detect: the sun and Jupiter. Jupiter is particularly interesting as interactions between Io and its ...
James K's user avatar
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25 votes

Is there any role today that would justify building a large single dish radio telescope to replace Arecibo?

Having a large dish gives you a large collecting area and hence better sensitivity. Building a multitude of receivers with the same collecting area, each having its own feed and electronics, is more ...
ProfRob's user avatar
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24 votes

How are radio telescopes pointed?

Well, even most optical telescopes aren't steered by hand and guided by human eyes - aside from a small fraction of objects, most sources are too dim to be seen by the naked eye or even with ...
HDE 226868's user avatar
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24 votes

"Next Generation Arecibo Telescope (NGAT)... would combine a 314-metre-wide platform with a swarm of 9-metre dishes on top" What would that look like?

There are a few diagrams in the original white paper (Anish Roshi et al. 2021; see Fig. 11) and the revised NGAT-130 proposal (Anish Roshi et al. 2023; see Fig. 3), depicting the basic arrangement. ...
HDE 226868's user avatar
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20 votes

What on-site equipment is installed with radio telescopes?

Though it will vary by telescope, some of those computers are likely used to control and monitor the telescope. The operator, who may be the astronomer but is usually an observatory staff member, ...
HDE 226868's user avatar
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18 votes
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Is there any role today that would justify building a large single dish radio telescope to replace Arecibo?

Single-dish telescopes have advantages over interferometers in a few areas; existing answers have touched on some of them. Collecting area is extremely important, as Rob Jeffries mentioned, and you ...
HDE 226868's user avatar
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15 votes

Building a floating, ocean-going giant radio telescope?

I would be extremely concerned about the ability of such a telescope to make adequately precise measurements, given the motion of the water. The leading radio telescopes have their mirrors and ...
HDE 226868's user avatar
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14 votes

Do radio telescopes see other stars better at night?

The Sun doesn't substantially impact radio observations during the day, because radio telescopes operate at long wavelengths. In general, light at longer wavelengths scatters less than light at ...
HDE 226868's user avatar
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13 votes

What will succeed the Arecibo Observatory?

As you said, the loss of Arecibo will definitely put a dent in the field of radio astronomy. As for what will help take its place - there are a couple options. Green Bank Observatory has been and ...
sforsingh's user avatar
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13 votes

What will succeed the Arecibo Observatory?

The big loss is to radar astronomy. Arecibo was one of only two radar telescopes in the world in regular use, and was by far the more powerful: a 300 meter antenna and megawatt transmitter, versus ...
Mark's user avatar
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13 votes

How are radio telescopes pointed?

There are several ways to point a radio telescope. Some radio telescopes are mounted with an optical telescope pointed in the same direction. The user moves the optical and radio telescopes together ...
Connor Garcia's user avatar
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11 votes

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

Would it increase the diameter if they would include some from there? No. Not by much, at least. The telescopes are already ~20,000 km apart, so you can't create a longer baseline that still has a ...
Hobbes's user avatar
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10 votes
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What radio frequency ranges are most beneficial for astronomy?

Radio astronomy involves a wide range of frequencies, covering the range from $\sim$10 MHZ to $\sim$100 GHz.$^{\dagger}$ With four orders of magnitude to work with, the most valuable band depends ...
HDE 226868's user avatar
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10 votes
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What is notable about LOFAR's sub-arcsecond radio resolution of distant galaxies? Does lower freq. range enable new capabilities that mm wave can't?

I'm one of the researchers involved with the International LOFAR Telescope (ILT) scientifically and technically, and have also contributed one of the papers and images you may have seen appear on ...
tikker's user avatar
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10 votes

Would it be possible to use existing radio-telescopes to do spot measurements of CMB?

Water vapour in the atmosphere emits microwave radiation, which interferes with the observation of the microwave background. For this reason, space telescopes such as COBE or WMAP are best placed to ...
James K's user avatar
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9 votes

Can I sense a bright star pointing an eight foot antenna towards it?

As others have noted, you will not be able to detect a star using an oscilloscope and an antenna. The received signal level is too low, and the oscilloscope not nearly sensitive enough. A radio ...
JRE's user avatar
  • 265
9 votes

Could we carve a large radio dish in the Antarctic ice?

The biggest limitation is that it would be in Antarctica, one of the most inhospitable places on Earth. Getting there is hard. Living there is harder. Everything needs to be flown in and if something ...
James K's user avatar
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9 votes
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Can one build a distributed radio telescope?

Yes, we can do radio astronomy with heterogeneous, geographically distributed antennas. The VLBI is an excellent example. Of course, the antennas have to be similar in some ways for it to work: If ...
Connor Garcia's user avatar
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8 votes

Can I sense a bright star pointing an eight foot antenna towards it?

Connecting an antenna directly to oscilloscope will not give reception, even with a strong radio source. First problem is the power level. Typical received power from antenna would be around -100 dBm,...
jpa's user avatar
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8 votes

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

tl;dr: @Hobbes' answer is demonstrably wrong; the EHT takes a large fraction of its data when the target is not visible from one of the extreme sites. If there were sites distributed all the way ...
uhoh's user avatar
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8 votes

Could we carve a large radio dish in the Antarctic ice?

Other answers deal with the properties of the ice sheet as a stable base for a precise-dimensioned equipment (it is not), the snow that will try to bury the telescope, etc, etc... A different from the ...
fraxinus's user avatar
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7 votes
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Does the "photo of a black hole" taken by EHT actually depict a visible light-based scenario?

You are right that the image is not a visible light image. It was taken using very, very short wavelength microwaves -- the wavelength is 1.3 mm which is only a bit shorter than the Far IR! I think ...
Mark Olson's user avatar
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7 votes
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Why does the Event Horizon Telescope (EHT) not include telescopes from Africa, Asia or Australia?

Why does the Event Horizon Telescope (EHT) not include telescopes from Africa, Asia or Australia? Why were not they included? Africa doesn't have a radio telescope in the frequency range necessary (...
Rob's user avatar
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7 votes

Are there any new/latest/recent radio sky surveys' data release which is publicly accessible?

"RACS and LoTSS have superb resolution and sensitivity." Those are both post-2000; RACS was completed in 2020 and LoTSS is still taking data. So I'm not entirely sure why you seem to exclude ...
Peter Erwin's user avatar
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7 votes

What on-site equipment is installed with radio telescopes?

Radio telescopes are a composite technical complex, the decomposition of which can be done as follows: The main one is an antenna device, an irradiator, a calibrator and a very sensitive receiving ...
dtn's user avatar
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6 votes
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How did single dish (or single receiver) radio telescopes originally generate images?

They scan the object, if you point the dish a a point in the sky as the Earth rotates the dish scans across astronomical objects, then move the dish to point at a slightly different position and let ...
James Screech's user avatar

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