<p>There is no universal answer to this question. Instrumentation, data formats and software differ greatly between telescopes. </p>

<p>Most software packages in use are written by astronomers as open source and shared and modified widely within the community. But instead of listing popular packages, perhaps a description of the common way of plotting images is a better answer here.</p>

<p>Consider a very basic radio telescope: A dish that's movable in two axis with a simple radiometer (think "power meter for RF") as the receiver. During an observation, you record four-tuples of time, azimuth, elevation and signal strength. Plotting these is pretty straightforward: Convert the instrument coordinates to celestial coordinates, and plot the signal strength over these coordinates. You'll get a classical <a href="https://www.nrao.edu/whatisra/images/grote5.gif" rel="noreferrer">intensity distribution map</a> (<a href="https://www.nrao.edu/whatisra/hist_reber.shtml" rel="noreferrer">source</a>). Those maps can be created using simple spreadsheet programs like Excel or custom code snippets.</p>

<p>Adding the capability to record spectra to your receiver makes the table you record your data in a bit more complex (since your last column is no longer a scalar value but a spectrum), and allows the creation of <a href="https://astropeiler.de/sites/default/files/styles/large/public/Galactic_scan_3m.png" rel="noreferrer">intensity-velocity-plots</a> (<a href="https://astropeiler.de/beobachtungen-mit-dem-3-meter-spiegel" rel="noreferrer">source</a>). From a software perspective, this is still a simple plot-points-in-2D excercise.</p>

<p>For anything more complex, especially array setups with multiple antennas and/or focal plane arrays, data reduction and plotting requirements are far more involved and highly depend on the actual setup. CASA and AIPS, mentioned in the comments above, are widely used packages, but there is a variety of custom code around.</p>

CC BY-SA 4.0
2019-08-13T12:00:56.343Z
2019-08-13T12:00:56.343Z
jstarek
<p>I'm very new to radio astronomy and I am curious how an the signals received by a radio antenna are converted to data on a computer and then images? Is there a popular software to use for this, or do astronomers typically write their own code?
Thanks in advance!</p>

CC BY-SA 4.0
2019-04-27T07:19:30.540Z
The code you're looking for is called "APES". They're also developing a new version called "CASA".
Phiteros
CC BY-SA 4.0
2019-04-27T07:37:29.743Z
Companion question: [Which techniques are used to convert radio signals received by antenna to images?](https://astronomy.stackexchange.com/q/31655/7982)
uhoh
CC BY-SA 4.0
2019-04-27T19:08:35.617Z
@Phiteros do you mean "AIPS"? Thanks for the pointer though, it's very helpful!
Thomas
CC BY-SA 4.0
2019-04-27T20:25:43.610Z
Yeah, I did. I hated that program, though, so I try to forget about it.
Phiteros
CC BY-SA 4.0
2019-04-29T15:41:49.617Z
"Converted to data" is a vague statement.  Inputs are digitized w/ timestamps applied, tagged as to current angular view, projected onto 2-D image planes, and lots more.
Carl Witthoft
<radio-astronomy><data-analysis>
How do astronomers convert radio signals received by their antenna to images?
Thomas
# How do astronomers convert radio signals received by their antenna to images?

(Asked by: username_0 on 2019-04-27)

I'm very new to radio astronomy and I am curious how an the signals received by a radio antenna are converted to data on a computer and then images? Is there a popular software to use for this, or do astronomers typically write their own code?
Thanks in advance!

**Tags:** radio-astronomy, data-analysis

> **Comments:**
> **username_1**: The code you're looking for is called "APES". They're also developing a new version called "CASA".  
> **username_2**: Companion question: [Which techniques are used to convert radio signals received by antenna to images?](https://astronomy.stackexchange.com/q/31655/7982)  
> **username_0**: @username_1 do you mean "AIPS"? Thanks for the pointer though, it's very helpful!  
> **username_1**: Yeah, I did. I hated that program, though, so I try to forget about it.  
> **username_3**: "Converted to data" is a vague statement.  Inputs are digitized w/ timestamps applied, tagged as to current angular view, projected onto 2-D image planes, and lots more.  

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## 1 answers

### Answer by username_4 on 2019-08-13. Score: 5

There is no universal answer to this question. Instrumentation, data formats and software differ greatly between telescopes.

Most software packages in use are written by astronomers as open source and shared and modified widely within the community. But instead of listing popular packages, perhaps a description of the common way of plotting images is a better answer here.

Consider a very basic radio telescope: A dish that's movable in two axis with a simple radiometer (think "power meter for RF") as the receiver. During an observation, you record four-tuples of time, azimuth, elevation and signal strength. Plotting these is pretty straightforward: Convert the instrument coordinates to celestial coordinates, and plot the signal strength over these coordinates. You'll get a classical [intensity distribution map](https://www.nrao.edu/whatisra/images/grote5.gif) ([source](https://www.nrao.edu/whatisra/hist_reber.shtml)). Those maps can be created using simple spreadsheet programs like Excel or custom code snippets.

Adding the capability to record spectra to your receiver makes the table you record your data in a bit more complex (since your last column is no longer a scalar value but a spectrum), and allows the creation of [intensity-velocity-plots](https://astropeiler.de/sites/default/files/styles/large/public/Galactic_scan_3m.png) ([source](https://astropeiler.de/beobachtungen-mit-dem-3-meter-spiegel)). From a software perspective, this is still a simple plot-points-in-2D excercise.

For anything more complex, especially array setups with multiple antennas and/or focal plane arrays, data reduction and plotting requirements are far more involved and highly depend on the actual setup. CASA and AIPS, mentioned in the comments above, are widely used packages, but there is a variety of custom code around.


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