Questions tagged [radio-astronomy]
Questions about observations performed in the radio frequency range of the electromagnetic spectrum.
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How to determine arrival time delay given dispersion measure?
In an online textbook, the following formula is given to calculate the arrival time delay between two frequencies, $v_1, v_2$ in a dispersed radio pulse:
$$t_1 - t_2 = 4.15 \cdot DM [(v_1/\text{GHz})^{...
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Why does the Fourier transform of this CMB image have a hole in it?
The BBC's Desert telescope takes aim at ageing our Universe contains the image below of the Cosmic Microwave Background from the Atacama Cosmology Telescope or ACT. It looks like this is plotted with ...
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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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Were radio spectroscopic observations ever used to first measure a distance successfully?
Usually, especially for an extragalactic object, its redshift is determined by optical spectroscopic redshift. But the angular resolution of early radio observations is poor and an optical counterpart ...
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How is VLBI delay calculated?
I’m working on a research project wherein we are trying to solve a problem very similar to VLBI delay. We have two radio receivers, and we know their locations. We also know at what time one receiver ...
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Why did it take five years to “figure out” how to use astrometric calibration sources to deblur LOFAR images?
Quanta Magazine's The Hidden Magnetic Universe Begins to Come Into View is a fascinating review of a rapidly evolving field in astronomy.
It contains some statements:
In their paper last year, van ...
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234 views
How is the field of view of a radio telescope determined?
It’s my understanding that radio telescopes can only receive signals that hit the dish within a certain range of angles. How is that angular range determined i.e. measured and/or calculated?
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How can I correct for transit time?
I know the exact time a radio telescope detected a transient event. I also know the exact location of the telescope, and the galactic coordinates (galactic longitude, latitude) and right ascension and ...
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Have non-periodic radio signals been analyzed for shannon entropy or put on a Zipf plot?
If aliens did exist, they would probably compress their communications. And they might use a fault tolerant infrastructure like TCP/IP. In either scenario, real communications would not be periodic ...
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In the 1950's how were radio-astrometric positions with portable dishes so precise they could be assigned to their dim optical counterparts (Quasars)?
In my question Why are quasars so far away that they couldn't be optically resolved in the 1950's? I included the following short paragraph, but then added strikethrough to the second sentence ...
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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 ...
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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 ...
asked Jun 9 '20 at 9:05
Chappo Hasn't Forgotten Monica
1,1682 gold badges10 silver badges24 bronze badges
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Do stars have “radio photospheres”? Are they different from their optical photospheres?
Comments below What is the maximum distance measurable with parallax? discuss challenges associated with parallax measurements of Betelgeuse and link to Wikipedia’s Betelgeuse; Distance measurements ...
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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 ($...
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1answer
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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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Options for observational astronomy [closed]
For getting into a PhD program for observational astronomy, is physics major and data science minor enough?
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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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How significant is the effect of galactic rotation on line broadening of carbon monoxide?
In class the other day, we were discussing observations of rotational transitions of carbon monoxide, namely, the $J=1\to0$ and $J=2\to1$ lines. We originally had assumed that both lines would have ...
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Cosmic Microwave Background Map
When a satellite takes measurements of the radiation from different patches of the sky to construct a map of the thermal radiation of the universe on the surface of a sphere, it would also contain ...
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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 ...
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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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Has radio astronomy ever been done on objects that appear very close to the Moon? Is this avoided?
This answer to Which kinds of astronomical observations most need to avoid the Moon being up? mentions
For completeness - radio, mid-infrared and mm-wave observations are unaffected (unless the ...
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Slope of log plot of luminosity-velocity in Tulley Fisher relation
My partner and I did some computation on the Tully Fisher relation at uni.
In that, the slope of the logarithm plot between the luminosity and rotational velocity, was 2.6.
Now, that slope ...
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1answer
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What is a “21cm/mm absorption system” in the context of measuring old photons from quasars?
This answer links to Wikipedia's Time-variation of fundamental constants which cites Further Evidence for Cosmological Evolution of the Fine Structure Constant (J. K. Webb et al. 2001), the abstract ...
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What was the field of view of the Ohio State University Radio Observatory of Wow! signal fame?
This answer to Did comets 266P/Christensen or P/2008 Y2 (Gibbs) cause the Wow! signal? points out that the comets in question were nowhere near where the radio telescope was pointed.
Wikipedia says ...
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Did comets 266P/Christensen or P/2008 Y2 (Gibbs) cause the Wow! signal?
Continuing my fascination with the Wow! signal, I stumbled upon an article from 2016 titled Famous Wow! signal might have been from comets, not aliens.
It describes the hypothesis that the signal ...
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How do radio astronomers avoid having their receivers burned out by ground-imaging radar from satellites?
After about 34:00 in the 9th press conference of AAS 235, radio astronomer and NRAO's spectrum manager Harvey Liszt talks about Radio Astronomy in a New Era of ...
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1answer
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Would “layered” radio interferometry work?
tl;dr - Is splitting up the process of interferometry as shown in the diagram possible, and if so, is it more efficient and/or easier than traditional methods?
I have been doing some research into ...
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What exactly is interplanetary scintillation; what was the Interplanetary Scintillation Array looking for? Did it successfully observe any?
The Interplanetary Scintillation Array is the radioastronomy observatory (i.e. big antenna) where the first pulsar was discovered by then graduate student Jocelyn Bell Burnell through careful and ...
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What can be learned from low frequency radio astronomy available outside of Earth's ionosphere?
As discussions and answers to How large does refraction become in radioastronomy? point out, it is difficult to do radio astronomy much below 30 MHz (or 10 MHz depending on how aggressive you are in ...
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How can I hear (or at least detect) a pulsar at home?
Scott Manley's video Using Relativistic Raytracing &X-Rays To See Detail on Surface Of Neutron Star talks about X-ray measurements using the NICER X-ray telescope attached to the International ...
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How to use the APARM, BPARM and CPARM of REGRD task in AIPS?
I plan to regrid a 500 by 500 image in B1950 to 500 by 500 in J2000 using the AIPS task REGRD. How to proceed?
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Rescaling a radio image
After a radio image has been cleaned it is advised that the fluxes be rescaled if the source is near the galactic plane. Can someone explain why this is needed?
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Creating a 2D matrix from 2 FITS images of unequal dimensions for Radio/FIR correlation
I have two images of NGC 6946:
...
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Could we detect an extraterrestrial signal with the SKA radio telescope?
As I have not seen this question answered and, following the rules: https://stackoverflow.blog/2011/07/01/its-ok-to-ask-and-answer-your-own-questions/ , I would like to answer this important question.
...
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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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who use the GADGET-2 pack for simulation? can I do it with my PC? [closed]
I want to do hydrodynamic simulatin for universe at vary redshifts. How can I do it?
or how can I find an simulation of universe for use my work?
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Open dataset from antenna array
I am looking for a raw radio-astronomic antenna array dataset of relatively modest size (on the order a few MB, or even less), to evaluate a data processing algorithm. The dataset ideally should be ...
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How to apply Fast Folding algorithm?
I have High Time Resolution Universe dataset. I have applied de-dispersion on this HTRU dataset, and thereafter I applied the folding function to fold the dataset.
How I can find that the periodicity ...
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Assuming no light pollution, was “2C. 1406” ever visible to the naked eye?
Joseph Needham, in his Science and Civilisation in China Vol. III, claimed that there was an ancient record of a nova about three thousand years ago. As a result of private correspondences with a "Dr ...
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How did Arecibo detect methane lakes on Titan, and image Saturn's rings?
This answer to Farthest distance to a solar system object that's been measured by radar? mentions that Saturn's rings, and the Uncover Travel post Arecibo Observatory, Puerto Rico – The World’s ...
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How to listen to our world from 10,000 light years away?
If you were 10,000 light years away from all radio stations and digital broadcasts from our world, what equipment would be necessary to detect and capture some information like a voice or a photo? If ...
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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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1answer
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How do I download PSRCHIVE and Tempo2 for pulsar timing on Mac Mojave?
I am fairly new to pulsar astronomy, and I need to download PSRCHIVE and then Tempo2. I have followed the instructions online here:
PulsarAstronomy.net
I'm also pretty new to linux commands/Mac ...
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Would radio telescope located anywhere within a 100 light year radius detect our radio emissions? [duplicate]
If there was a radio telescope, as sophisticated as our best radio telescopes within a 100 light year radius from earth.
AND if its sole purpose was search for signs of artificial/intelligent radio ...
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Requirements for an amplifier and filter for a horn antenna-based 21 cm radio telescope?
We are looking into the possibility of building a low budget horn antenna for detecting 21 cm hydrogen line radiation (~1420 MHz) and and possibly measuring its spectrum.
What are the types of ...
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How far have individual stars been seen by radio telescopes?
Writing this answer got me thinking.
As far as I understand it, stars themselves radiate most of their energy at optical wavelengths (near-IR through near-UV).
Various types of stellar objects may ...
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1answer
101 views
From whence is the Event Horizon Telescope black hole data available for amateur reconstruction?
Ralf Vandebergh's tweet shows his own reconstruction of an image of the accretion disk around a black hole, generated presumably from Event Horizon Telescope data.
I'm assuming that the data came ...
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1answer
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What Is The Maximum Distance Our Finest Instruments Could See When They're Perfected?
Radius of the observable universe is 47.5 billion light years,which means we are seeing things which are about 48 billion light years away. At a rough estimate,at what distance would our finest ...
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How is it determined that the X-ray and radio intensity come from a magnetic field bridge between two clusters of galaxies?
Gizmodo's Astronomers Spot Mysterious, 10-Million-Light-Year-Long Magnetic Field Connecting Two Galaxy Clusters shows the image below, and Space.com's A Weird 'Radio Bridge' 10 Million-Light Years ...
