Questions tagged [interferometry]
Questions about astronomical observations which involve superimposing waves received by multiple, physically separated, receivers to obtain higher angular resolution.
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About angular diameter, parallax and image of the nearest neutron star RX J185635-3754
I have a big doubt about our allegedly nearest (X Ray isolated) neutron star, also known as the Walter star, one of the members of the "Magnificent Seven stars": RX J185635-3754.
So I came ...
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Angular diameter and length of baseline
How did they determine the angular diameter, please? How to predict the baseline length with the first lobe?
Thank you.
https://www.chara.gsu.edu/public/basics-of-interferometry
If they are ...
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Could we hear alien radio transmissions using radio interferometry?
Suppose money and engineering wasn't a concern. Could we actually build a bunch of radio telescopes in space, and use radio interferometry, so that we could actually hear the sort of radio ...
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Telling bounces in LIGO interferometer
How do they know the number of times the laser bounces back and forth, in the 4 km arms of the interferometer, before the laser light is picked out to the reading sensor?
See under “The Longer The ...
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W in the brightness distribution
What is W in the brightness (intensity) distribution, please?
Alpha is the position of the star; lambda, the wavelength; t, the time; P, the polarization.
Thank you
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Squared visibility in astronomy
Why is preffered to use squared visibility instead of visibility in long-baseline interferometry, please?
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Why hasn't VLBI been used to try and image giant exoplanets?
A Jupiter-sized object at 10 pc subtends an angle of 0.0001 arcseconds (100 micro-arcsec) at the Earth. The Event Horizon Telescope interferometry network is capable of a (demonstrated) angular ...
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How does Very Long Baseline Interferometry work?
According to internet sources, this technique increases the effective diameter of the telescope, thus improving the angular resolution of the telescope. However I don't understand how this actually ...
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Can the Hubble constant be measured directly?
By my calculations, the expansion of the universe should cause LIGO’s interferometers to alternate between constructive interference and destructive interference every couple days. Is this a practical ...
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Mega Telescope using gravitational lensing and interferometry
I have been thinking about this crazy telescope idea, but I am not smart enough to understand if it's technically possible. I understand from an engineering and practical point of view it's a long way ...
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What is stopping Event Horizon Telescope the size of the Earth’s orbit?
There is a proposal to include a radio sensor in a telescope going to the Sun-Earth L2, getting 120x improvement in angular resolution to EHT. Knowing nothing about interferometry, it seems pretty ...
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In terms of results, how similar is a bunch of telescopes across the globe to an Earth-sized telescope?
The Event Horizon Telescope emulates an Earth-sized telescope by syncing a bunch of radio telescopes across the planet to do take pictures with a small enough angular resolution to take pictures of a ...
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If we put a radio telescope on Mars and use it in array with earth radio telescopes, how much will we able to see?
If we put a radio telescope on Mars and use it in array with earth radio telescopes, how much will we able to see? Will it allow us to see planets, like we do with black hole?
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Response function of LIGO
"Laser Interferometer Gravitational-wave Observatory" (LIGO) is a marvel of precise engineering and the world's largest gravitational wave observatory. LIGO, which consists of two massive ...
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Maximum number of pixels across a synthesized beam in an ALMA image?
I have some ALMA data, from which I have created images using the TCLEAN task in CASA.
I understand that with this type of data, it is necessary to have at least 2 pixels across the FWHM of the ...
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Are there any space-based observatories that use interferometry?
Ground-based interferometers such as ALMA have enabled many discoveries. It seems like sending a fleet of small telescopes would be feasible (smaller telescopes are easier to send into space than ...
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Have interference effects (in space) ever been observed by a single instrument, as opposed to interferometry?
Not asking about:
Interferometry can be done with multiple instruments who's light paths or signals are combined interferometrically, or even between different parts of a single aperture, e.g.
What ...
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Estimate upper limits on flux values in the case of a non-detection?
I have ALMA data which are non-detections of some spectral lines in a protoplanetary disk. The data is in the form of spectral cubes. I am hoping to estimate an upper limit on the flux of each of the ...
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rms noise, confusion and dynamic range in radio images
I have been trying to understand imaging in radio astronomy. Below are some of my questions related to it and my understanding of their answers. I am not very confident about my understanding of them ...
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Convert from Jy/beam km/s to W/m$^2$
I need to compare some ALMA observations of a protoplanetary disk to disk-integrated fluxes obtained from a model.
The ALMA observations are upper limits of non-detected spectral lines, where the RMS ...
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How does speckle imaging fit in to 21st century high resolution imaging from ground based observatories?
Phys.org's Astronomers uncover evidence that there could be many more Earth-sized planets than previously thought references Speckle Observations of TESS Exoplanet Host Stars. II. Stellar Companions ...
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Reference request (explaining) how optical correlators combine light from multiple telescopes to produce ultra-high resolution interferometric images?
This is a reference or resource-request because it may be too challenging to explain in an answer post, but if you'd like to attempt a short summary as well, that will be great!
I have a basic ...
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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 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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Was GRAVITY built to look at one star?
GRAVITY (shown below) is a interferometric combiner of near infrared light from four very large telescopes called The Very Large Telescope in order to make careful astrometric measurements near the ...
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What does a narrow-band "point spread function" look like for long exposures from the VLT's large interferometric aperture?
In interferometric radio astronomy UV plots are the first step in understanding what a point spread function (PSF) will look like for a given location in the sky observed over a period of time. The ...
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In astronomical interferometry, what values do the points in the uv-plane have?
As I understand it, the image of an interferometer is the inverse fourier transform of the information in the uv plane. For each baseline (vector between any two telescopes in the array), representing ...
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The role of 'the interference of waves' in VLBIs'
I've been trying to find out how VLBIs work. It says in this book I've read that many radio telescopes around the world work in tandem to use the interference of waves to get a clearer picture of ...
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Why does the Simbad page "A.A. Michelson's Jovian Galilean-satellite interferometer" show data for Betelgeuse?
When searching for things related to How did Michelson measure the diameters of jupiter's moons using optical interferometry? I came across the ui.adsabs.harvard.edu entry A. A. Michelson's Jovian ...
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How did Michelson measure the diameters of jupiter's moons using optical interferometry?
In Betelgeuse: How its Diameter was measured (Chant, C. A., Journal of the Royal Astronomical Society of Canada, Vol. 15, p.133, Bibliographic Code: 1921JRASC..15..133C) the author says:
The paper in ...
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What is the difference between these various Angular Resolution formulas?
I have recently learned about angular resolution and its dependence on the ratio λ/D. There seem to be three different equations for angular resolution that I have come across. One of these has the ...
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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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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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LIGO: How can laser interferometry (wavelength >$10^{-7}$m) detect length changes of arms <$10^{-18}$ m?
I'm trying to understand the sensitivity of the LIGO interferometer. I've been reading around lots of discussion of how they manage noise cancellation between the two detectors, achieving a very pure ...
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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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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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Can the interferometer called "Gravity" measure "a few centimeters on the Moon"?
Phys.org's Very Large Telescope sees star dance around supermassive black hole, proves Einstein right links to several ESO videos, including Interview with Reinhard Genzel (in English). After ...
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Why don't we build an interferometer between Earth and the Moon?
The Event Horizon Telescope (EHT) does interferometry from an array of telescopes spread all across Earth. The data is locally stored on a hard drive and shipped to a central location, so the ...
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Is it possible to overcome the problem of blind spot(s) of current gravitational wave detectors?
If gravitational waves (GWs) pass through specific points (which are known as blind spots), current GW detectors aren't able to detect the passing waves. In the future, will we be able to completely ...
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How do they know the non-uniformities seen on the disk of π¹ Gru are real and not artifacts?
@RobJeffries' answer to What is this web on the surface of the Sun? explains why convection cells on some other stars can be far larger than they are on our Sun and includes a near-infrared VLT ...
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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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Will the Magdalena Ridge Optical Interferometer be able to image extended objects like the surface of the Moon?
Inspired by several questions:
When will a moon landing site be visible via telescope?
Could the E.H.T. produce an image of the human artifacts on the moon?
Picture of equipment left on the Moon?
...
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mm-wavelengths Moon map, scientific case
I would like to test a telescope with a Moon observation.
It is a low spectrometer-imager at 110-300 GHz with a resolution of 4 arcmin@150 GHz.
Is there any scientific target that concerns the Moon ...
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Two body orbit dynamics for orbital periods approaching light cone limit
How do you model a system of two large celestial bodies, where they achieve a rotation very close to the limit at which information can escape the system (heat, light, etc.), do they begin to appear ...
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Does interstellar cloud obstruct or reduce the visibility?
We just pictured a medium distant black hole by combining data from various observatories around the world. That's when I wondered if interstellar cloud blocks the visibility at multiple position in ...
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How does the Large Binocular Telescope resolve so well in both orthogonal directions simultaneously?
The Forbes article Ask Ethan: How Does Very-Long-Baseline Interferometry Allow Us To Image A Black Hole? includes an example of optical interferometry from the Large Binocular Telescope, shown below.
...
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Why not us interferometry to take a picture of Pluto?
Interferometry is among the best ways (if not, the best way!) to have an image of a very distant object.
Recently a picture of the black hole at the center of M87 was released. It is the result of ...
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What are the challenges for the building and data analysis of the CHIME telescope?
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has discovered the second repeated fast radio burst recently. However, its structure is simple apparently. I wonder why we did not build a ...
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Estimate the number of pixels required to map the full primary beam of a Radio Telescope station
I am practising some exam questions for a radio interferometry exam, and I am struggling with this question:
The physical size of a single LOFAR station, operating at 150MHz is about 50m.
Estimate ...
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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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