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Questions tagged [radio]

Questions about the part of the electromagnetic spectrum with wave lengths longer than those of infrared radiation.

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3 votes
1 answer
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Has optical interferometry been done at radio frequency using heterodyning with a laser in a nonlinear material?

If one collects narrow band optical emission from a large telescope with frequency $f_1$ and mixes it in a nonlinear crystal with laser light of a nearby frequency $f_2$, it would produce two new ...
uhoh's user avatar
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3 votes
1 answer
209 views

Current topics on Radio Astronomy and looking for advice

Background and Question: I'm an undergraduate student interested on Radio Astronomy. I consider myself enthusiastic about it and I project myself following this "path" so I'd like, ...
nuwe's user avatar
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10 votes
1 answer
375 views

Can one build a distributed radio telescope?

I understand some radio telescopes are built as arrays of receivers. Could one build an array from a heterogeneous set of receivers in scattered locations? Suppose a large number of persons each ...
Joe Cooper's user avatar
1 vote
1 answer
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Why space-based VLBI scattering sub-structure is "Hopefully, a new promising tool to reconstruct the true image of observed background target(s)"?

@HDE226868 mentioned in the observatory that the GBT@20 – The Celebration; Twenty Years of Innovation and Discovery was going on. There are plenty of YouTube videos and slide sets available as links. ...
uhoh's user avatar
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6 votes
1 answer
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How do we know that comets definitely mase and not just fluoresce? What is it about 18-cm lines that indicates that is really masing per se?

Wikipedia's Astrophysical_maser#comets mentions some anecdotes of notable masers associated with comets, and Maser emissions from comets begins: The 18-cm lines of the OH radical are the only well-...
uhoh's user avatar
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4 votes
1 answer
302 views

How bright is the Sun in S-band?

As far as I can tell when the Voyagers listen to Earth they have the Sun in the same beam. I never did calculate how bright a blackbody Sun would be because I have no idea if that's representative of ...
uhoh's user avatar
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3 votes
1 answer
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What does the Sun "look like" below 100 MHz?

Radio2space.com's The Radio Sun says: At very low frequencies (below 0.1 GHz) and therefore at very long wavelengths (> 3m) the solar disk appears much bigger and brighter in the center, and its ...
uhoh's user avatar
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1 vote
1 answer
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What's known about Odd Radio Circle appearance? What would they look like if we could see them? Are they transparent/translucent in radio, or opaque?

update: March 2022: Phis.org: Astronomers reveal best image yet of mysterious odd radio circles in space Science Alert: Weird Circular Objects Observed in Space May Finally Be Explained MNRAS: ...
uhoh's user avatar
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