Questions tagged [radio]
Questions about the part of the electromagnetic spectrum with wave lengths longer than those of infrared radiation.
26
questions
2
votes
1answer
42 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 ...
0
votes
1answer
98 views
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?
10
votes
1answer
184 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 ...
0
votes
1answer
46 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. ...
4
votes
1answer
58 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 ...
4
votes
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 ...
8
votes
1answer
129 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 ...
3
votes
1answer
91 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, ...
2
votes
0answers
22 views
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 ...
3
votes
1answer
81 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....
4
votes
1answer
165 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 ...
1
vote
1answer
172 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 ...
1
vote
0answers
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. ...
2
votes
1answer
124 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 ...
4
votes
1answer
142 views
How do we know that comets definitely mase and not just fluoresce?
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 ...
3
votes
1answer
222 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 ...
4
votes
0answers
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, ...
6
votes
1answer
141 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 ...
2
votes
2answers
539 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 ...
3
votes
0answers
550 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{...
3
votes
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 $\frac{1 Jy}{beam}$?
2
votes
2answers
133 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?
1
vote
0answers
47 views
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 ...
2
votes
0answers
35 views
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 ...
3
votes
1answer
330 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 ...
-6
votes
2answers
280 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 ...
