<p><a href="https://splatalogue.online//advanced1.php" rel="noreferrer">Splatalogue</a> is an excellent resource that allows you to search for spectral line transitions for a given atomic/molecular species within a specified wavelength range. It compiles data from a number of sources, including JPL, the Cologne Database for Molecular Spectroscopy (CDMS), and Lovas/NIST.</p>
<p>If you are looking for more detailed information than just the wavelengths, I recommended either going to <a href="https://cdms.astro.uni-koeln.de/cgi-bin/cdmssearch" rel="noreferrer">CDMS</a> directly, or using the Leiden Atomic And Molecular Database (<a href="https://home.strw.leidenuniv.nl/%7Emoldata/" rel="noreferrer">LAMDA</a>). This provides details such as Einstein A coefficients, energy levels and collisional data for a small number of key molecular species.</p>

CC BY-SA 4.0
2021-08-14T14:28:25.873Z
These are great, thanks! Do you know if Splatalog, CDMS or LAMDA are *used by astronomers* to look up standard, accepted values for spectral features? I haven't asked for a recommendation, I've asked for what sources astronomers usually use.
uhoh
CC BY-SA 4.0
2021-08-15T09:03:13.893Z
@uhoh I am a PhD astrophysics student, so I can only speak for myself and colleagues. But yes, we use these tools regularly. For example, Splatalogue is very helpful when putting together a telescope proposal, to identify which lines lie within a particular spectral window. Data from CDMS/LAMDA is incorporated directly into computer models to allow the gas chemistry to be accurately simulated.
lucas
CC BY-SA 4.0
2021-08-15T09:05:08.350Z
Then that sounds pretty conclusive, *thanks!*
uhoh
CC BY-SA 4.0
2021-08-14T07:54:26.943Z
2021-08-14T07:54:26.943Z
lucas
<p>When identifying isolated observed spectral features or fitting complex observed spectra or even running complex numerical simulations, one needs a reliable, standard table of known wavelengths and other parameters like splitting, intensity relationships, etc.</p>
<p><strong>Question:</strong> Where do Astronomers usually get their wavelengths?  Are there a few favorite references where astronomers turn to look up standard, accepted values for spectral features?</p>
<p>Somewhat related:</p>
<ul>
<li><a href="https://astronomy.stackexchange.com/q/44999/7982">Vacuum and air wavelengths in spectroscopy</a></li>
</ul>

<observational-astronomy><astrophysics><spectroscopy><data-analysis><spectrometry>
Where do Astronomers usually get their wavelengths? Where do they turn to look up standard, accepted values for spectral features?
uhoh
# Where do Astronomers usually get their wavelengths? Where do they turn to look up standard, accepted values for spectral features?

(Asked by: username_0 on 2021-08-13)

When identifying isolated observed spectral features or fitting complex observed spectra or even running complex numerical simulations, one needs a reliable, standard table of known wavelengths and other parameters like splitting, intensity relationships, etc.

**Question:** Where do Astronomers usually get their wavelengths? Are there a few favorite references where astronomers turn to look up standard, accepted values for spectral features?

Somewhat related:

* [Vacuum and air wavelengths in spectroscopy](https://astronomy.stackexchange.com/q/44999/7982)

**Tags:** observational-astronomy, astrophysics, spectroscopy, data-analysis, spectrometry

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## 1 answers

### Answer by username_1 on 2021-08-14. Score: 5 | Accepted answer

[Splatalogue](https://splatalogue.online//advanced1.php) is an excellent resource that allows you to search for spectral line transitions for a given atomic/molecular species within a specified wavelength range. It compiles data from a number of sources, including JPL, the Cologne Database for Molecular Spectroscopy (CDMS), and Lovas/NIST.

If you are looking for more detailed information than just the wavelengths, I recommended either going to [CDMS](https://cdms.astro.uni-koeln.de/cgi-bin/cdmssearch) directly, or using the Leiden Atomic And Molecular Database ([LAMDA](https://home.strw.leidenuniv.nl/%7Emoldata/)). This provides details such as Einstein A coefficients, energy levels and collisional data for a small number of key molecular species.

> **Comments:**
> **username_0**: These are great, thanks! Do you know if Splatalog, CDMS or LAMDA are *used by astronomers* to look up standard, accepted values for spectral features? I haven't asked for a recommendation, I've asked for what sources astronomers usually use.  
> **username_1**: @uhoh I am a PhD astrophysics student, so I can only speak for myself and colleagues. But yes, we use these tools regularly. For example, Splatalogue is very helpful when putting together a telescope proposal, to identify which lines lie within a particular spectral window. Data from CDMS/LAMDA is incorporated directly into computer models to allow the gas chemistry to be accurately simulated.  
> **username_0**: Then that sounds pretty conclusive, *thanks!*  

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