39
votes
Accepted
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 ...
- 36k
36
votes
Accepted
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 ...
- 36k
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-...
- 3,103
31
votes
Accepted
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 ...
- 31.3k
29
votes
Accepted
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 ...
- 116k
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 ...
- 146k
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 ...
- 36k
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. ...
- 36k
18
votes
Accepted
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 ...
- 36k
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 ...
- 36k
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 ...
- 36k
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 ...
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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 ...
- 3,103
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 ...
- 16.2k
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 ...
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10
votes
Accepted
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 ...
- 36k
10
votes
Accepted
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 ...
- 316
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 ...
- 116k
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 ...
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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 ...
- 116k
9
votes
Accepted
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 ...
- 16.2k
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,...
- 1,600
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 ...
- 2,786
7
votes
Accepted
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 ...
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7
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 ...
- 31.3k
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 ...
- 16.4k
6
votes
Accepted
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 ...
- 1,223
6
votes
Amateur radioastronomy: dish suggestions
The size of your dish determines two things:
Along with the temperature of your electronics, determines the signal-to-noise ratio of your telescope.
The size of your dish determines the angular ...
- 606
6
votes
Accepted
Did Arecibo's secondary optics compensate aberrations when viewing farther away from vertical?
While the statement in the block quote about the sphere is correct as far as it goes, was the shape of the correcting optics (secondary, etc) above also independent of where you look? Or ideally would ...
- 2,319
6
votes
Accepted
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 (...
- 2,616
Only top scored, non community-wiki answers of a minimum length are eligible