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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 ...
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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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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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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4 votes
Accepted

Why do we call radio images "maps"? Is it because it is not optical, so therefore not an "image", strictly speaking?

There is no distinction. No matter which wavelength regime you consider, "image" is an adequate and frequently used description. Also for radio, microwaves, sub-mm, IR, UV, and X-rays. The ...
pela's user avatar
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3 votes

Could we hear alien radio transmissions using radio interferometry?

For the sake of discussion, let's assume there is a signal out there that we might possibly detect. This question hits on one of the big weaknesses of interferometry as compared to a really huge ...
Darth Pseudonym's user avatar
2 votes

Greetings to Altair: what is the probability of detecting a return message, assuming one was sent?

@ProfRob's link gives some very interesting numbers. The Arecibo dish can detect [a million watt signal it emitted] at a distance of about 5000 light years. The dish has a diameter of 304m. and ...
Dragon's user avatar
  • 241
2 votes

Measuring Expansion Rate of Crab Nebula with Radio Spectrum Scan

I'm familiar enough with the 20m that I can at least answer the instrumental part of your question -- what the graphs are displaying. Since about 2014, the 20m has had an L-band receiver, with a ...
HDE 226868's user avatar
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1 vote

is there any site with historical radiotelescope data about observations 21 cm line Hydrogen (1.42 GHz)?

The whole SETI project started by making observations on this frequency, using the Big Ear telescope. My recommendation is go to the wikipedia page about the Wow! Signal and follow the links from ...
1 vote

Could we hear alien radio transmissions using radio interferometry?

Radio waves are a part of the electromagnetic spectrum, and if transmitted using an omnidirectional antenna, they are subject to the inverse square law, which shows how the initial signal strength (or ...
jmarina's user avatar
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1 vote
Accepted

How do we get -0.4 mJy/beam in the the 1.28 GHz MeerKAT Galactic Center Mosaic?

Astronomical radio emission is typically much weaker compared to ambient (terrestrial) emission, e.g., emission by the atmosphere, the telescope, the surroundings, and the receiver, so one needs to ...
Markus Roellig's user avatar
1 vote

Do high power radar astronomers try to avoid beaming power at (at least some) artificial satellites as they pass overhead?

Yes, If the satellite is at zenith do have protocols and codes to address this like Arecibo dishes. 140 W is a lot less, as compared to the solar constant and even normal lasers, which is not ...
Arjun's user avatar
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