# Tag Info

## Hot answers tagged radio-astronomy

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 ...
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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-...
• 3,041
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 ...
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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 ...
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24 votes
Accepted

### How did Arecibo detect methane lakes on Titan, and image Saturn's rings?

Titan "lakes": Published Open Access in Science: Radar Evidence for Liquid Surfaces on Titan Campbell, D. B., Black, G. J., Carter, L. M., and Ostro, S. J., Science 302, 5644, pp. 431-434, 17 Oct ...
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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 ...
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23 votes
Accepted

### A "strange" unit radio astronomy

I would expect the authors to be talking about the signal in terms of janskys, the now-commonly-used units of flux density. The typical definition is 1\text{ Jansky}=10^{-26}\text{ Watts meters}^{-2}...
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21 votes

### Why does the Fourier transform of this CMB image have a hole in it?

Having now looked at the paper by Aiola et al. (2020), it emerges that for that map, they filtered the data to exclude low frequency multipoles with $|l|<150$, corresponding to about 1 degree. This ...
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19 votes
Accepted

• 34.6k
11 votes

### Artificial radio waves masked by a star's natural radio waves?

The Sun emits incoherent radio signals over the full range of frequencies. The signals are not modulated in any meaningful way. Humanity emits signals at particular frequencies that are then modulated ...
• 129k
10 votes

### Why are radio telescopes shaped so differently than optical telescopes?

They're not different. Same principles do apply. You could have secondary, tertiary, quaternary, and so on, mirrors with instruments at any wavelength, either optical, or radio, or infrared, etc. You ...
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10 votes
Accepted

### Why aren't ground-based observatories using adaptive optics for visible wavelengths?

There's a pretty good discussion at this page. There are several factors at work: The smaller isoplanatic angle, as you note. This limits how much of the sky you can observe with AO, since your ...
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10 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 exactly is interplanetary scintillation; what was the Interplanetary Scintillation Array looking for? Did it successfully observe any?

To fully answer your questions, let me introduce scintillation before interplanetary scintillation. Atmospheric scintillation The imaging of an astronomical source is affected by a collection of ...
• 400

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