Questions tagged [radio]
Questions about the part of the electromagnetic spectrum with wave lengths longer than those of infrared radiation.
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What is Euclidean fluence scaling in the context of bounding constraints on FRB all-sky rates? Would non-Euclidean scaling give a different answer?
The recent Chromatic periodic activity down to 120 MHz in a Fast Radio Burst contains two paragraphs in which X's are given "assuming an Euclidean fluence scaling".
To me, a non-astronomer, ...
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1answer
38 views
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?
The BBC's Astronomers see galaxies in ultra-high definition covers some news related to papers in Astronomy & Astrophysics' dedicated, open access issue Sub-arcsecond imaging with the ...
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How to superimpose an optical image upon a radio contour image using AIPS?
I am using AIPS by NRAO. I am trying to overlay a radio contour image with an optical image in the r-band. From the cookbook I could not find the suitable command for it. Both are fits files pf course....
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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?
The Conversation's ‘Dancing ghosts’: a new, deeper scan of the sky throws up surprises for astronomers says:
We are getting used to surprises as we scan the skies in the Evolutionary Map of the ...
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1answer
44 views
In radio astronomy, why do shorter baselines trade angular resolution for surface brightness?
I'm reading about radio astronomy and array configurations on the Very Large Array's (VLA) website. They state that the longest baselines provide the best angular resolution, but have very limited ...
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1answer
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Is **Voyager I’s** reduced data transmission rate as described in [this article][1] because of the distance or because its transmitter getting slower? [closed]
Is Voyager I’s reduced data transmission rate as described in this article because of the distance or because its transmitter getting older & slower?
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1answer
193 views
Do radio telescopes see other stars better at night?
As you know, we don’t see stars with the naked eye during the day because of the visible glare of our Sun.
As I understand our Sun emits radio frequency waves, too. Is there a radio ‘glare’ from the ...
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1answer
48 views
Why is space-based VLBI scattering sub-structure "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. ...
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75 views
What is the significance of the velocity resolution in spectral line observations using radio interferometry?
I've always struggled to conceptualize the term "velocity resolution" in spectral observations. In principle, it is simple to calculate. For example, one can take the spectral width and ...
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1answer
59 views
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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139 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 ...
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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, ...
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The electron–cyclotron maser emissions from Earth
The first-ever detection of radio signals caused by the electron–cyclotron maser mechanism outside of the Solar System, on Tau Bootis b was recently published (here). This phenomenon causes huge radio ...
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1answer
82 views
Would the electron cyclotron-maser emission mechanism affect Proxima b's ability to retain an atmosphere?
In a recent arXiv preprint, Pérez-Torres et al. "Monitoring the radio emission of Proxima Centauri" claim the detection of radio emissions synchronised with the orbit of the planet Proxima b....
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1answer
178 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 ...
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1answer
259 views
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 ...
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36 views
How can I determine the location of an object for one observer given the location for another?
I know an object exists at the location of the beam-pointing-center of a radio telescope. I know the elevation/azimuth of the beam pointing center, as well as it’s “location” in galactic coordinates. ...
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1answer
126 views
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 ...
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1answer
161 views
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 ...
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1answer
224 views
Current delay for radio signals from the Mars InSight mission
I've been meaning to post it on the day when InSight landed but just got around to it now.
When they broadcasted landing in real-time, it really wasn't in real-time because radio signals from Mars ...
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106 views
What EM spectrum can stars be most cheaply observed using Remote Sensing during the day?
I would like to augment my GPS navigation with remote sensing of 'the sky.' I am looking for any astronomical body that can be perceived during the day.
Maybe Pulsars emit something easily detected, ...
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1answer
142 views
What explains this puzzling radio signature from a fireball?
September 21, 2017 a bright fireball over Holland was reported by hundreds of people. Several all-sky cameras recorded it as well as a special radio beacon set up to capture radio signatures of ...
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2answers
564 views
How to calculate the integrated source flux density of a continuous source?
I'm working with data from radio surveys. My images are .fits files with BUNIT Jy/beam. I want to calculate the net flux from a continuous source (not point source). When I simply added all the ...
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570 views
Radiometer Equation for Flux Density
In Duncan and Lorimer's Handbook of Pulsar Astronomy, the equation for the flux density using a radio telescope is given as (for a top-hat function):
$$S=\frac{\beta\,\mathrm{SNR}\, T_{sys}}{G\sqrt{...
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1answer
2k views
Why levels of radio contours maps are given in mJy/beam and what does it mean?
I know what a jansky is, but I don't understand what beam (in $\frac{1 Jy}{beam}$) is.
If jansky is a unit of flux density, what kind of unit is $\frac{1 Jy}{beam}$?
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2answers
140 views
How do astronomers at SETI know if they received intelligent radio signals from other planets?
Do they expect to see wave modulations like the ones we use in our technology? what do they expect the waves to be like exactly?
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Detecting people on Proxima Cen b [duplicate]
Recently the news announced the discovery of a planet with characteristics similar in size to earth with the possibility for liquid water, 4.2 light years away.
Now, if there was a civilisation of ...
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When does oscillation of interplanetary plasma occurs?
When does oscillation of interplanetary plasma occur?
When and what are the reasons of the excitation of this plasma that makes it oscillate? Does it oscillate when is not excited?
Can extremely ...
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1answer
335 views
Need help with the math in Python program to flag Jovian radio emissions
A few days ago I decided to take on the little project of converting a Qbasic program into Python (as a side project to my Radio Jove project), and I've managed to get it to run, but the math is ...
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2answers
289 views
Why does the Southern hemisphere seem to be short of radio telescopes? [closed]
In northern hemisphere, we have GBT, Arecibo, Parkes, Jodrell and VLA, while
in southern hemisphere, only Australia has big radio telescopes.
ALMA is in Chile, but it is in sub-mm.
Is not ...
