Questions tagged [radio-astronomy]
Questions about observations performed in the radio frequency range of the electromagnetic spectrum.
345
questions
1
vote
0
answers
44
views
Calculate change in spectral line intensity for a change in temperature
I am trying to do some simple modelling of spectral line emission. I am starting with some ALMA observations of a protoplanetary disk, where the emission from a particular molecule at frequency 344GHz ...
- 1,366
0
votes
1
answer
41
views
How to calculate radio luminosity at a certain frequency from observed radio flux density at another frequency?
$L_R$ can basically calculated by $L_R= v * L_v$ where $v$ is frequency and $L_v=4* \pi * D^2 * F_v$ where $F_v$ is flux density at a certain frequency $v$. I have observational flux density data at $...
- 67
0
votes
1
answer
45
views
1
vote
0
answers
38
views
Space-based radio telescope array
I’m wondering about the abilities of a technology: You may have heard of the Square Kilometer Array. The array is focused by adjusting the timing of the individual antennas.
Q: Could this array be ...
- 11
5
votes
1
answer
552
views
Would it be possible to use existing radio-telescopes to do spot measurements of CMB?
With CMB peaking at roughly 158GHz would it be possible to create a more precise map of CMB just by sampling 'points' using existing Earth-based radio telescopes? I understand that large dish ...
- 161
2
votes
1
answer
91
views
S0-2 (S2) Diameter/Radius
I'm a student, I am doing an investigation about S0-2. My idea was to take the wavelength that emanates from the star.
When I saw the data from Science magazine I found a problem that was that the ...
2
votes
1
answer
104
views
is there any site with historical radiotelescope data about observations 21 cm line Hydrogen (1.42 GHz)?
I am looking for an open source that contain historical raw data or (meta)data about historical observations of the 21 cm line hydrogen made via radio telescopes.
- 21
4
votes
2
answers
70
views
Radio Astronomy Data Handling (Filtering What One Needs)
Suppose we have some radio astronomy data for some specific moment (not a time series). Can we, using some computer program, filter out and get, say, only the data (EM radiation), whose sources are at ...
- 41
2
votes
1
answer
60
views
What are the differences between different types of flux density in radio astronomy?
I am new to radio astronomy and have started to analyze some radio observational data of pulsars recently. I am wondering about the differences between "peak flux density", "integrated ...
- 23
2
votes
1
answer
65
views
How do we get -0.4 mJy/beam in the the 1.28 GHz MeerKAT Galactic Center Mosaic?
Dr. Becky's Feb. 11, 2022 video Move over JWST! 5 new telescopes to get excited for makes a quick mention of this image produced by the Meerkat array and published in Heywood et al. 2022 The 1.28 GHz ...
- 31.4k
6
votes
1
answer
214
views
Do high power radar astronomers try to avoid beaming power at (at least some) artificial satellites as they pass overhead?
This answer to "Next Generation Arecibo Telescope (NGAT)... would combine a 314-metre-wide platform with a swarm of 9-metre dishes on top" What would that look like? links to an interesting ...
- 31.4k
20
votes
1
answer
2k
views
"Next Generation Arecibo Telescope (NGAT)... would combine a 314-metre-wide platform with a swarm of 9-metre dishes on top" What would that look like?
In Nature News' August 11, 2023 Closing down an icon: will Arecibo Observatory ever do science again? found in The Observatory there is discussion of the Next Generation Arecibo Telescope (NGAT):
...
- 31.4k
4
votes
1
answer
177
views
Greetings to Altair: what is the probability of detecting a return message, assuming one was sent?
Greetings to Altair was a 1983 transmission to Altair, 16.7 light years distant, sent on the 46m Stanford radio telescope, known as "The Dish". [Quast 2018]
Assuming an alien civilisation ...
- 191
1
vote
1
answer
58
views
What is the effective area of VLASS?
I need to calculate NRAO VLA Sky Surveys effective area that's been held in 1998. (The observation of 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)). I couldn't find the exact values, tried many ...
- 67
1
vote
0
answers
42
views
How to calculate a part of a spectrum from another part of it?
I have some radio data (flux) in 1.4 GHZ and also distance data. I calculated the luminosity for this frequency. Here, i want to use power-law and/or blackbody relation to calculate possible ...
- 67
1
vote
0
answers
64
views
How to find integrated radio flux for the 21-cm line due to HI content in a dwarf galaxy?
Suppose I have a rough estimate of HI gas content (in solar mass units) in a local dwarf galaxy located at a distance say d parsec (at some RA and Dec co-ordinates) with a half-light radius r and I am ...
0
votes
0
answers
178
views
Typical astronomical and astrophysical problems in various programming languages
As a rule, work in the field of observational astronomy and astrophysics requires knowledge of such programming languages as: C/C++ and the principles of OOP, MPI, CUDA. Sometimes additional ...
- 285
1
vote
1
answer
81
views
What is the relation between column density and surface density of neutral hydrogen gas HI?
I know the column density distribution of neutral hydrogen gas (units: cm^-2). I want to calculate the corresponding surface density distribution of the neutral hydrogen gas (units: M_solar/pc^2). How ...
- 194
2
votes
0
answers
74
views
How to transform between horizontal and equatorial coordinates?
I want to express the transformation between horizontal (azimuth $A$,elevation/altitude $\varepsilon$) coordinates and equatorial (hourangle $H$/right ascension $\alpha$, declination $\delta$) as a ...
- 141
1
vote
1
answer
53
views
Transforming radio sources in a T-RECS catalogue from one field to another
I have sources that I extracted from The Tiered Radio Extragalactic Continuum Simulation (T-RECS) catalogue for a deep field. I use these sources to generate a sky model at different fields within a ...
- 11
1
vote
1
answer
180
views
Help converting Jansky/beam to erg s^-1
I have some radio observation data in jansky/beam from NVSS at 1.4GHZ, and I want to convert these values into luminosity values (erg/sec).
I have the distance data and I made a formula to convert it:
...
- 67
0
votes
2
answers
132
views
What was FJM Stratton doing during Kamishari Expedition 1936, linked to Pearl Harbor intelligence?
In 1936, FJM Stratton, renowned Cambridge prof astrophysicist-radioastronomer, less-known but true, GC&CS-GCHQ intelligence officer and specialist FJM Stratton, led his Kamishari Expedition to ...
- 21
0
votes
0
answers
55
views
Creating a small data pipeline
I wanted to create a small data pipeline such that it consists of images of sky in the filters F125W, F160W, F606W and F850LP. The 4 images for a single object should be in a single FITS File which ...
3
votes
0
answers
69
views
What are radio frequencies sensitive to in galaxies?
Apart from 21cm line studies, radio emissions as well as signatures of different radio sources, do radio frequencies help in the identification of a particular physical structure or presence of some ...
- 627
3
votes
0
answers
69
views
Questions about the Cocconi Morrison paper on interstellar communication
I have been reading the paper by Cocconi and Morrison on interstellar communication and I have trouble understanding their formulas.
The paper begins by stating, that a star similar to the quiet sun ...
- 151
0
votes
0
answers
49
views
Galactic rotation curves data samples: how to get them?
I am aiming to introduce data Science to my High-School students and I thought about giving to them data taken from galactic rotation curves (spiral galaxies at the moment) to stude the flatness of ...
- 399
1
vote
1
answer
69
views
What parameters about galaxies can be measured using SAO DS9?
I am trying to determine and plot various parameters for galaxies on SAO DS9. RA & dec, angular size to a fair extent, and contour plotting are a few of the aspects which I could determine using ...
- 627
3
votes
0
answers
90
views
How will China's Xuntian space telescope use its Terahertz capability? THz Spectroscopy? Imaging? Something else?
An Update on the Chinese Space Station Telescope Project Hu Zhan, National Astronomical Observatories, CAS, KIAA, Peking University, On behalf of the CSST Team, ISSI-BJ Workshop: Weak gravitational ...
- 31.4k
5
votes
2
answers
120
views
Are there any new/latest/recent radio sky surveys' data release which is publicly accessible?
There are many sky surveys that have been conducted by telescopes in different wavelengths of the electromagnetic spectrum like DSS (Digitized Sky Survey), SDSS (Sloan Digital Sky Survey), WISE (wide-...
- 627
2
votes
0
answers
34
views
Where can I find MITEoR 150 Mhz radio data?
I was working on the Aladin Sky Atlas v12 software and while working on the radio data, I came across this Radio sky survey that said MITEoR 150 MHz. Initially, I mistook it to be GMRT because GMRT ...
- 627
12
votes
2
answers
231
views
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 ...
- 146k
1
vote
3
answers
110
views
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 ...
- 779
7
votes
1
answer
152
views
SKA 101: How will it "perform the most precise tests of Einstein's theories" and Australia & South Africa arrays be "made to work seamlessly together"
The BBC's December 7, 2022 SKA: Construction to begin on world's biggest telescope includes the following:
It will perform the most precise tests of Einstein's theories
and
The first major ...
- 31.4k
3
votes
0
answers
47
views
Negative flux values in radio maps?
I am trying to understand some maps of radio emission in e.g the Milky Way. I continue to see in papers that these radio maps report negative values of the flux in Jansky units, although no ...
- 623
2
votes
0
answers
86
views
We are making a 5 meter diameter radio telescope dish by using metal mesh and need some advice and/or reference designs [closed]
We are making a 5 meter diameter radio telescope dish.
What metal should we use and what must be the size of the mesh if the targeted frequency is 1430 Hz?
Also what might a simple but stable ...
- 29
4
votes
0
answers
81
views
First satellite of an asteroid (or double asteroid) ever imaged by delay-Doppler radar?
In comments about my previous bounty on the Space SE question Which deep-space spacecraft flew closest by Earth during a gravitational assist?, I started to look at the Galileo mission and ran across ...
- 31.4k
4
votes
2
answers
883
views
Radio signals between Mercury and the Moon during an eclipse
This is a hypothetical question. Thank you for your time and efforts.
A signal is sent from a transmitter on Mercury's surface while it is at its greatest western or eastern elongation. The signal is ...
- 171
2
votes
2
answers
120
views
In radio astronomy, do two dimensional sensors exist?
Is there an equivalent of CCD/CMOS sensors for non-optical wavelengths?
(not looking for alternative/indirect methods like interferometry)
- 1,648
5
votes
1
answer
63
views
How to interpret illumination in "pulsar cannonball" image
This beautiful image (from APOD) looks like the trail of the ejected pulsar is illuminating a ball of gas and dust. My eye sees patches of light and shadow, but sometimes images can be deceptive. What ...
- 3,691
2
votes
0
answers
172
views
Calculate the uncertainty in measured flux density from an integrated intensity map
I have some ALMA data, in the form of a spectral cube, which I have integrated along the velocity axis to create an integrated intensity ('moment 0') map.
The integrated intensity map shows emission ...
- 1,366
3
votes
0
answers
72
views
Source flux in Jy + noise computation, radio astronomy
I have an image of an extended source obtained with an interferometer (after imaging the uv-data). The image consist of a certain number of pixels, with unit of Jy/beam. Somewhere on the image is a ...
- 61
3
votes
0
answers
74
views
What is the maximum distance we could detect incidental radio signals from aliens? [duplicate]
I've been getting interested in the Fermi Paradox discourse again, and something's been bugging me about the assumptions we could actually detect incidental radio signals from aliens, or vice versa.
...
- 31
1
vote
0
answers
69
views
Has anybody measured the mass density profile $\Sigma = \Sigma (r)$ of a protoplanetary disk? (when $r<1$ AU)
I've been trying to find research articles where the mass density distribution $\mathrm{\Sigma = \Sigma(r)}$ is determined for protoplanetary disks, when $r<1$ au. For instance:
Here A. Miotello, ...
- 605
1
vote
1
answer
72
views
Why was the NVSS(NRAO VLS Sky Survey) conducted at 1.4 GHz continuum?
I am observing the nature of some galaxies looking at their radio images and contours from NVSS. So, the data collected have radio flux at other wavelengths but I am studying it at 1.4GHz. I have been ...
- 65
0
votes
1
answer
75
views
Where can I get a step by step guide to use CASA for obtaining a radio image of a planet like say Jupiter?
I intend to use CASA for processing ALMA data for Jupiter and obtain a proper radio image for Jupiter.
However, is there any specific step by step guide for the same just as is the following for TW ...
- 627
3
votes
1
answer
141
views
Method to get data from NED IPAC and NVSS, without manually giving RA/dec input
I am collecting the radio flux data at 1.4Ghz frequency for all 1544 Markarian Galaxies for a study. For that, I have to first put the names of these Markarian galaxies in NED IPAC and from there ...
- 65
6
votes
2
answers
91
views
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 ...
- 1,718
2
votes
1
answer
54
views
How and where can I get the continuum and/or FITS data for Jupiter and Saturn from ALMA, GMRT and VLA Telescopes?
I intend to process and analyze the radio images and emissions from Jupiter and Saturn. I wish to get data from ALMA, GMRT and VLA Telescopes. Requesting you to please guide me as to how do I access ...
- 627
2
votes
0
answers
86
views
Why hasn't the EHT taken an image of Sgr A*? [duplicate]
The Event Horizon Telescope or EHT took an image or the black hole at the center of M87 in 2019, and in 2021 it measured the polarization of the light from M87*. Right after the first image of M87* ...
- 17.4k
1
vote
1
answer
109
views
How is CASA different from SAO DS9?
I was told that CASA is used extensively in Radio Astronomy. However, softwares like SAO DS9 and also python (Astropy) are also used for radio astronomy data analysis. So, what makes CASA different as ...
- 627