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Questions tagged [radio-astronomy]

Questions about observations performed in the radio frequency range of the electromagnetic spectrum.

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Request for Information on how to make a FITS Image

I know that at the end of the Receivers in Radio Telescopes, after the final Amplifier the analog signal will be given to the ADC. Now this ADC converts the analog signal into a stream of binary bits. ...
G.B. Raghavkrishna's user avatar
1 vote
0 answers
30 views

Are continuum observations in NVSS contaminated by HI spectral line?

The NVSS survey has been carried out at 1.4 GHz. From what I could gather, the bandwidth of the NVSS survey includes HI 21 cm (~1.420 GHz) emission line. Suppose I have a region of the sky in which I ...
kkr01's user avatar
  • 11
2 votes
0 answers
25 views

How to convert .exp files from NRAO VLA Archive to .fits format

I recently downloaded some observational data files from the NRAO VLA Archive, and they have the extension .exp. These are old observations. I need to convert these files to .fits format for further ...
Eduardo Quiroz's user avatar
3 votes
0 answers
47 views

Why are there red- and blue-shifted radio lobes on either side of the core for collimated bipolar outflows?

This is a velocity integrated picture of a molecular cloud, part of my homework. https://paste.c-net.org/AthenaMeasly Question: For collimated bipolar outflows, the general situation is that the red-...
Firestar-Reimu's user avatar
4 votes
0 answers
79 views

DIY Radio Telescope (High School)

Background: I am attempting to build an RTL-SDR-based radio telescope for detecting hydrogen lines (21 cm) as a project with my HS Physics class. Several accounts are online, including parts lists ...
Stan Forrester's user avatar
0 votes
0 answers
60 views

Looking straight through the Milky Way Galaxy with the Gedanken Space Telescope from radio to 100 keV, what would the opacity vs wavelength look like?

Imagine that the "Large Gedanken Cryogenic Space Telescope" has been commissioned and aligned and is ready for its first test. It is equipped with a closed-cycle helium refrigerator to ...
uhoh's user avatar
  • 30.7k
4 votes
1 answer
543 views

Can an astronomer fully work remotely? [closed]

My question today is addressed to those astronomers who have quite a lot of experience working remotely. In general terms, the answer to the question includes the following elements: the range of ...
ayr's user avatar
  • 853
1 vote
1 answer
82 views

Why do we call radio images "maps"? Is it because it is not optical, so therefore not an "image", strictly speaking?

Or is it just historical convention? I know that within research circles, it is common to also use the term "radio image". I am mainly wondering whether the term originally comes from ...
Loika's user avatar
  • 177
6 votes
0 answers
134 views

Radius of hydrogen cloud

I am using a 1.4 meter parabolic dish with HPBW of 10 degrees and a RTLSDR to study our milky way in hydrogen line. The structure of the galaxy is deduced as shown in the picture by plugging the ...
radastro's user avatar
  • 115
2 votes
2 answers
103 views

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 ...
Adrian's user avatar
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2 votes
0 answers
56 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 ...
lucas's user avatar
  • 1,386
1 vote
1 answer
152 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 $...
Ege Tunç's user avatar
0 votes
1 answer
74 views

Type Error: WCS.slice() takes from 2 to 3 positional arguments but 4 were given

My code: ...
柳吉羽's user avatar
1 vote
0 answers
45 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 ...
Joe D's user avatar
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5 votes
1 answer
565 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 ...
user2820052's user avatar
2 votes
1 answer
124 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 ...
Nicolás Vallejos's user avatar
2 votes
1 answer
114 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.
Rad's user avatar
  • 21
4 votes
2 answers
78 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 ...
avpol's user avatar
  • 41
2 votes
1 answer
150 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 ...
tzu18's user avatar
  • 23
2 votes
1 answer
82 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 ...
uhoh's user avatar
  • 30.7k
7 votes
1 answer
280 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 ...
uhoh's user avatar
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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): ...
uhoh's user avatar
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4 votes
1 answer
193 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 ...
Dragon's user avatar
  • 241
1 vote
1 answer
63 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 ...
Ege Tunç's user avatar
1 vote
0 answers
48 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 ...
Ege Tunç's user avatar
1 vote
0 answers
76 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 ...
RADagASTtheBROWN's user avatar
1 vote
0 answers
220 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 ...
ayr's user avatar
  • 853
1 vote
1 answer
188 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 ...
SlightDecoy's user avatar
2 votes
0 answers
237 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 ...
condosz's user avatar
  • 141
1 vote
1 answer
60 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 ...
Supremum's user avatar
1 vote
1 answer
518 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: ...
Ege Tunç's user avatar
0 votes
2 answers
147 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 ...
M McLoughlin's user avatar
0 votes
0 answers
61 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 ...
Astrophile's user avatar
3 votes
0 answers
71 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 ...
Dhruv Nayak's user avatar
3 votes
0 answers
71 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 ...
Alexander Cska's user avatar
1 vote
1 answer
107 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 ...
Dhruv Nayak's user avatar
3 votes
0 answers
103 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 ...
uhoh's user avatar
  • 30.7k
5 votes
2 answers
127 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-...
Dhruv Nayak's user avatar
2 votes
0 answers
37 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 ...
Dhruv Nayak's user avatar
13 votes
2 answers
257 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 ...
ProfRob's user avatar
  • 156k
1 vote
3 answers
136 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 ...
Ambica Govind's user avatar
7 votes
1 answer
157 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 ...
uhoh's user avatar
  • 30.7k
3 votes
0 answers
60 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 ...
math_lover's user avatar
2 votes
0 answers
96 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 ...
killbox72's user avatar
6 votes
1 answer
136 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 ...
uhoh's user avatar
  • 30.7k
4 votes
2 answers
895 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 ...
JM Yaden's user avatar
  • 171
2 votes
2 answers
123 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)
2080's user avatar
  • 1,800
5 votes
1 answer
65 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 ...
Mark Foskey's user avatar
  • 3,944
2 votes
0 answers
271 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 ...
lucas's user avatar
  • 1,386
3 votes
0 answers
104 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 ...
Jylu's user avatar
  • 61

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