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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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1 vote
0 answers
28 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 ...
2 votes
0 answers
20 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 ...
3 votes
0 answers
40 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-...
7 votes
1 answer
277 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 ...
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 ...
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 ...
4 votes
1 answer
537 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 ...
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 ...
1 vote
1 answer
80 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 ...
6 votes
0 answers
132 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 ...
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 ...
2 votes
0 answers
55 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 vote
1 answer
132 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 $...
0 votes
1 answer
72 views

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

My code: ...
13 votes
1 answer
153 views

How can maser emission be unpolarized?

I was reading that: However, unlike Galactic sources such as W3(OH), the emission is unpolarized and the 1667 MHz line is stronger than the 1665 MHz line. but how is this possible? Does not the ...
7 votes
1 answer
160 views

Has SETI searched the solar system for life?

I know SETI is searching the stars for radio signals emitted by advanced alien civilizations, but has SETI searched inside our solar system - particularly moons, planets, and Lagrange points? I would ...
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 ...
2 votes
1 answer
112 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.
5 votes
1 answer
560 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 ...
2 votes
1 answer
121 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 ...
4 votes
2 answers
76 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 ...
3 votes
2 answers
270 views

Just how fast is a Fast Radio Burst thought to be?

According to Wikipedia's Fast Radio Bursts; Features are recorded they The component frequencies of each burst are delayed by different amounts of time depending on the wavelength. This delay is ...
2 votes
1 answer
80 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 ...
3 votes
1 answer
184 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 ...
2 votes
1 answer
136 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 ...
4 votes
1 answer
192 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 ...
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): ...
1 vote
1 answer
59 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 ...
1 vote
1 answer
62 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 ...
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 ...
4 votes
2 answers
218 views

How significant and accessible is modern Chinese astronomy?

Is China fully integrated in the international astronomical community, or does military secrecy and language problems and sanctions (ITAR) or something else stand in the way? Does China have valuable ...
33 votes
4 answers
3k views

What will succeed the Arecibo Observatory?

Just a few minutes ago, I got a notification from Space.com stating that the Arecibo Observatory will be, sadly, decommissioned due to extensive damage to its structure. So, with the loss of one of ...
1 vote
0 answers
72 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 ...
1 vote
0 answers
217 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 ...
1 vote
1 answer
166 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 ...
2 votes
0 answers
201 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 ...
1 vote
1 answer
465 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: ...
0 votes
2 answers
143 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 ...
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 ...
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 ...
12 votes
2 answers
899 views

Why aren't ground-based observatories using adaptive optics for visible wavelengths (circa 2016)?

Adaptive Optics (AO) techniques allow ground based observatories to dramatically improve resolution by actively compensating for the effects of Astronomical Seeing. The atmospheric effects are quite ...
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 ...
2 votes
1 answer
220 views

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 ...
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 ...
2 votes
3 answers
264 views

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 ...
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 ...
1 vote
1 answer
105 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 ...
5 votes
2 answers
126 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-...
53 votes
4 answers
7k views

Is there any role today that would justify building a large single dish radio telescope to replace Arecibo?

It seems that most of the modern radio astronomy instruments and observations that make the news are interferometers or phased array systems of one kind of another. Is there any application left for ...
11 votes
1 answer
2k views

How big a dish do I need for radio astronomy?

I've recently become interested in the idea of building my own small-scale radio telescope. A quick online search finds a few instructions on how to build this using a satellite dish. These suggest a ...

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