<p>If you're looking explicitly for radio-loud quasars, I'd recommend looking at a catalog of (mainly extragalactic) radio sources, rather than a catalog of quasars, given that only a small fraction of quasars are radio-loud.</p>
<p>The <a href="https://en.wikipedia.org/wiki/Third_Cambridge_Catalogue_of_Radio_Sources" rel="nofollow noreferrer">Third Cambridge Catalogue of Radio Sources</a> (<a href="http://vizier.cfa.harvard.edu/viz-bin/VizieR-3?-source=VIII/1A&amp;-out.max=50&amp;-out.form=HTML" rel="nofollow noreferrer">VizieR link</a>) might be a nice starting point, particularly given how many objects are referred to by their 3C designation, although not all of the objects listed there are quasars - there are plenty of Seyfert galaxies and a small number of pulsars. As an example, <a href="https://ned.ipac.caltech.edu/byname?objname=3C+286&amp;hconst=67.8&amp;omegam=0.308&amp;omegav=0.692&amp;wmap=4&amp;corr_z=1" rel="nofollow noreferrer">here's the NED entry for the quasar 3C 286</a>, along with its SED:</p>
<p><a href="https://i.sstatic.net/RJDb0.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/RJDb0.png" alt="SED of quasar 3C 286" /></a></p>
<p>The 3C survey was conducted at 159 MHz and then 178 MHz, so you'll certainly see lots of very low-frequency sources in there, which sounds ideal for your purposes. Again, though, this is just a starting point, and your mileage may vary if you opt for other catalogs.</p>

CC BY-SA 4.0
2021-07-17T18:09:51.400Z
2021-07-17T18:09:51.400Z
HDE 226868
<p>Using data from <a href="https://ned.ipac.caltech.edu/" rel="nofollow noreferrer">https://ned.ipac.caltech.edu/</a>, I can get nice-looking spectral energy distributions for quasars, such as for these two:
<a href="https://i.sstatic.net/t8UNP.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/t8UNP.png" alt="enter image description here" /></a>
<a href="https://i.sstatic.net/wIiak.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/wIiak.png" alt="enter image description here" /></a></p>
<p>but most of their points are in UV to IR range. I'm looking particularly for quasars with lots of radio points (i.e. frequency &lt; 1e12 Hz), since that's the region I'm using in my research.</p>
<p>In the link above, you search for objects by name, but I don't know the names of any quasars with lots of points in the radio range. Are there any known like this? I only need a couple, as examples in my report.</p>

<radio-astronomy><spectroscopy><quasars>
Radio SEDs for quasars
Jim421616
# Radio SEDs for quasars

(Asked by: username_0 on 2021-07-16)

Using data from <https://ned.ipac.caltech.edu/>, I can get nice-looking spectral energy distributions for quasars, such as for these two:
[![enter image description here](https://i.sstatic.net/t8UNP.png)](https://i.sstatic.net/t8UNP.png)
[![enter image description here](https://i.sstatic.net/wIiak.png)](https://i.sstatic.net/wIiak.png)

but most of their points are in UV to IR range. I'm looking particularly for quasars with lots of radio points (i.e. frequency < 1e12 Hz), since that's the region I'm using in my research.

In the link above, you search for objects by name, but I don't know the names of any quasars with lots of points in the radio range. Are there any known like this? I only need a couple, as examples in my report.

**Tags:** radio-astronomy, spectroscopy, quasars

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## 1 answers

### Answer by username_1 on 2021-07-17. Score: 2 | Accepted answer

If you're looking explicitly for radio-loud quasars, I'd recommend looking at a catalog of (mainly extragalactic) radio sources, rather than a catalog of quasars, given that only a small fraction of quasars are radio-loud.

The [Third Cambridge Catalogue of Radio Sources](https://en.wikipedia.org/wiki/Third_Cambridge_Catalogue_of_Radio_Sources) ([VizieR link](http://vizier.cfa.harvard.edu/viz-bin/VizieR-3?-source=VIII/1A&-out.max=50&-out.form=HTML)) might be a nice starting point, particularly given how many objects are referred to by their 3C designation, although not all of the objects listed there are quasars - there are plenty of Seyfert galaxies and a small number of pulsars. As an example, [here's the NED entry for the quasar 3C 286](https://ned.ipac.caltech.edu/byname?objname=3C+286&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1), along with its SED:

[![SED of quasar 3C 286](https://i.sstatic.net/RJDb0.png)](https://i.sstatic.net/RJDb0.png)

The 3C survey was conducted at 159 MHz and then 178 MHz, so you'll certainly see lots of very low-frequency sources in there, which sounds ideal for your purposes. Again, though, this is just a starting point, and your mileage may vary if you opt for other catalogs.


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