Questions tagged [radio-astronomy]

Questions about observations performed in the radio frequency range of the electromagnetic spectrum.

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6
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2answers
731 views

Why does radio astronomy offer higher resolution images than optical?

According to this lecture,"Radio astronomy has several advantages over optical astronomy...We can make the highest resolution images, and see things happening on the smallest scales." Why is this? If ...
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When do radio and tv signals become indistinguishable from background noise of the universe?

I understand the rate an EM signal broadcast uniformly from the Earth will decrease in its power is governed by the inverse square law. How far from Earth will radio and tv signals become ...
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How accurately could late 50s - early 60s humans have mapped the solar system?

What if early SETI investigations had focused on our own solar system, rather than distant stars? Given the technology that existed around the 1950s, how much surveillance would humanity be able to do?...
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Is there a recent update on the mysterious M82 radio source reported in 2010?

The Wikipedia page on the "Cigar Galaxy" (M82) has the following summary about an "unknown object": In April 2010, radio astronomers working at the Jodrell Bank Observatory of the University of ...
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Is there any update on the Availability of Event Horizon Telescope Images?

There has been no news on the obvious public channels from the EHT project since last (Northern) summer. Does anyone have more information on when any results from the April 2017 run might be released?...
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How does ALMA produce stable, mutually coherent ~THz local oscillators for all of their dishes?

The ALMA (Atacama Large Millimetre/submillimetre Array) radio telescope's band-10 capabaility is now operational, per this answer. That's confirmed by NRAO's First Science with ALMA’s Highest-...
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Early universe's first starlight (indirectly) detected for the first time, could it have been detectable with 1970's technology?

The recent paper in Nature An absorption profile centred at 78 megahertz in the sky-averaged spectrum seems (to me at least) to be an incredibly simple and elegant experiment with far-reaching ...
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What is precipitable water vapor in millimeter-wave radioastronomy and how is it measured?

Looking through ALMA on-line documentation and articles, the quantity PWV (precipitable water vapor) is a central theme. I have two linked questions. What (actually) is precipitable water vapor, and ...
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343 views

How did Jocelyn Bell Burnell discover the periodicity of CP 1919?

According to Wikipedia, in 1967, a radio signal was detected using the Interplanetary Scintillation Array of the Mullard Radio Astronomy Observatory in Cambridge, UK, by Jocelyn Bell Burnell. The ...
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86 views

Do the neutrons in neutron stars emit the radio waves?

Neutrons can, especially in extreme circumstances (and large concentrations) emit electromagnetic radiation. I specifically asked about this in Physics S.E. Has a free neutron ever been shown to ...
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697 views

Radio Astronomy and Imaging

So, I've been starting to investigate radio astronomy, and am wondering about if certain things are possible from an amateur standpoint. I was looking at this powerpoint(that discusses building a tiny ...
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What could a cloud of mini radio dishes see?

Suppose an astronomer gave a 1 m radio dish to 500 people scattered over the face of the Earth and connected them to the internet. The people are directed to set their radio antennae up in their ...
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What is the role of the mesh on which dipole elements of the MWA antennas are placed?

I was reading about the radio telescope - Murchison Widefield Array (MWA) situated in Western Australia. Antennas of this telescope are quite unique and different from the usual dish radio telescope. ...
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201 views

Brightest Radio Source In the Universe

I would have assumed that the brightest radio source in the Universe is a quasar of some kind (perhaps 3C 273) given that the average pulsar has luminosity of $~10^{40} \text{Watts}$ and this is the ...
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211 views

What's the highest frequency that's been imaged by a radio telescope?

In this answer to Should we update definitions and remove the 100 GHz hard limits on radio astronomy related tags? I wrote the following partial answer: Yes, there are plenty of dishes that focus ...
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Is there work underway to push the long baseline capabilities of the Event Horizon Telescope to sub-millimeter wavelengths?

The Max Planck Institute for Radio Astronomy's press release Something is Lurking in the Heart of Quasar 3C 279; First Event Horizon Telescope Images of a Black-Hole Powered Jet shows a stunning ...
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What is a radio “homology telescope” and is the 500m dish in China one?

This question is about design aspects of large radio telescope dishes which allow them to flex under the influence of gravity as they change elevation angle, and still maintain good optical ...
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635 views

Building a floating, ocean-going giant radio telescope?

Given the loss of the Arecibo telescope: Is anybody aware of any efforts or studies towards a floating, ocean-going radio telescope of with 500m diameter and more? The idea is floating (pun intended) ...
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228 views

Has the microwave background radiation ever been blocked in order to prove it's really from the sky?

A rather stupid question but I was just curious if the radiation could be virtual. From the instrument....sort of like virtual particles. In other words if you just build a sensitive microwave ...
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242 views

How to know that the 21cm Hydrogen line is the actual emission and not any other redshifted line?

Is it possible that we mistake some other wavelength emission to be 21 cm because of redshift?
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What types of signals is SETI (and other such efforts) looking for?

This seemed to be the closest group for this question. Every few months there are a few articles asking "Are we alone in the universe" which focus on the Fermi Paradox, the Drake Equation, and end by ...
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Is there an advantage to the equatorial region of the far side of the moon for a radio telescope or would any crater on the far side work?

If nearly any crater on the far side of the moon will work, and not just equatorial craters, then we could pick craters near the possible future Artemis base at the South pole which would allow easier ...
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Where was this photo of Nancy Grace Roman taken, what is the display shown?

Where was this photo of Nancy Grace Roman taken, what is the display shown, is there any technical information on this display and where is it now? If this is a NASA photo then there should be an ...
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How do or could radio telescopes contribute to exoplanet studies?

Current and upcoming telescopes which find exoplanets and take spectra of their atmospheres seem to be optical or infrared. What about radio telescopes applied to exoplanets? They are larger and more ...
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Is there another explanation, apart from the doppler effect, for the redshift observed in distant galaxies?

On episode 10 of the original Cosmos TV series, Carl Sagan mentions that some scientist don't agree that the redshift observed in distant galaxies is evidence of the big bang, stating that probably ...
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How can the Event Horizon Telescope image Sgr A* when it's not visible from all sites at one time?

I went to https://eventhorizontelescope.org/array and read about the ten sites listed as part of the EHT, I have a mashed-up screen shot of them below. I made a little script also shown below with ...
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Which wavelength is the most quiet, for a ground-based radio telescope?

This might seem like a backwards question, but I'm interested in what wavelength to select in a (hypothetical) ground-based radio telescope observation to expect detecting as little as possible! :) ...
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How LOFAR pass through the ionosphere?

The LOFAR project open a new window in the universe's study because it allows to receive low frequences of the universe that we could not get because of the ionosphere. But I'm wondering how can ...
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258 views

2SB mixer in radio astronomy?

In literature about the instrumentation of radio astronomy, I frequently come across a type of mixer described as "2SB". I'm familiar with single-sideband (SSB) and double-sideband (DSB) mixers, but ...
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Event Horizon Telescope Data Cleanup

I was wondering how the researchers were able to minimize or neutralize confirmation bias regarding the data collected? As I understand it, the algorithm pruned much of the data, which would make ...
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Is broadcasting the location of Earth to potential extraterrestial civilization regulated?

How many times have we broadcast the location of Earth to the outer space? Are there any regulation in doing so? I know so far we have send the Arecibo Message, and any receiver can trace the message ...
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125 views

Can astronomical radio sources be used as a verifiable randomness beacon?

A randomness beacon is a source of random data that is broadcast to multiple parties. Users listening to the beacon receive the same sequence of random strings and no one can predict the values in ...
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123 views

Can weak gravitational lensing or microlensing-induced wavefront distortion limit resolution of absurdly large aperture telescopes?

This is a theoretical question. This answer to the question If we had the right technology could we see a distant star in detail? (presumably space-based) primarily addresses the scaling of ...
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Nature and mechanism of the short-term variability in radio strength of Sgr A*?

The Phys.org article Cosmic filament probes our galaxy's giant black hole links to A Nonthermal Radio Filament Connected to the Galactic Black Hole? which discusses (among other things) the importance ...
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Is “Giga-hertz Astrophysical Transient Emission” distinct in any way from “Fast Radio Burst”?

In this answer I have just read about The University of Texas Rio Grande Valley's The Spacecraft Tracking and Astronomical Research into Giga-hertz Astrophysical Transient Emission (STARGATE). While ...
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Recommend a radio calibration target for amateur radio telescope

I have a small antenna and radio system that can receive frequencies between 1MHz and 1GHz. The system has a discone antenna. I plan to do some aperture synthesis based on the daily rotation of the ...
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How far have stars been seen beyond the center of the Milky Way?

What lies near the center of the galaxy is of great interest and in recent times the motion of dozen(s) of stars at the center of our galaxy orbiting around Sgr A* have been measured in great detail. ...
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What does “unremarkable transverse peculiar velocity” mean exactly, and how is it calculated here?

The abstract of A magnetar parallax (also in MNRAS) contains the following: Combining our new observations with two archival observations from 2006, we have refined the proper motion and reference ...
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613 views

Why is 3GHz the best frequency at which to measure the sun's microwave output?

I have read that 3GHz is the best frequency at which to measure the sun's microwave output, but that measurements are made at 2.8GHz for historical reasons, however I can find no explanation of why ...
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Converting Jy/beam to Jy?

Maybe its a dumb question, but to convert Jy/beam to Jy, I just have to multiply it by the beam size in sr right? Being $\Omega$ the beam size: $\Omega = \frac{\pi \theta_{maj} ~~ \theta_{min}}{4 \...
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Can radio telescopes such as arecibo image the subsurface of asteroids or planets?

This was done with the moon: Radio Dishes Peer Beneath Moon's Surface
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Can SETI certify whether or not Proxima b is inhabited by beings using electromagnetic communication?

Can SETI certify whether or not Proxima b is inhabited by beings using electromagnetic communication? By certify I mean by past, present or future observations using technologies available.
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What exactly are “H30α and He30α images”? (ALMA)

I ran across this paper's title η Carinae: high angular resolution continuum, H30α and He30α ALMA images (arXiv) and see that the body of the paper also mentions "H40α, H30α and H29α". What ...
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Is there a complete edition of the Cambridge Catalogue of Radio Sources (esp. 3C) available digitally?

In radio astronomy, many common objects are refered to by their designation from the 3rd Cambridge Catalogue of Radio Sources, e.g. 3C 353. For hobbyist purposes, I would like to create a catalogue ...
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518 views

What determines which frequency range a radio telescope has?

My simple understanding is that a parabolic dish focuses radio waves to a receiver. It is obvious that any parabola focuses visible light and heat, so I assume that it focuses all radio wavelengths ...
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What is the significance of using baseline pairs in radio interferometry?

Radio interferometry utilizes arrays of smaller telescopes that are linked together to synthesize a larger aperture telescope. Astronomical radio observatories, such as the Very Large Array in New ...
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Does the “photo of a black hole” taken by EHT actually depict a visible light-based scenario?

I'm still at my bachelor of electronic and communications engineering, so I'm not an expert of radiotelescopes; however, I surely know that, typically, radio communications are characterized by a RX ...
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MeerKAT's Epic Image of the Galactic Centre, what are we seeing?

In this answer as well as this one, I've linked to New Jersey Institute of Technology's Dr. Dale Gary's nicely-written Physics 728 Radio Astronomy; Lecture #1 notes where I can see the image below. It ...
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Flux density from brightness map

This is a naive question. I have a temperature map of radio emission at 1420 MHz, in Kelvin. I want to extract the flux density (in Janskys) from an extended region of this map. Is the flux density ($...