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AtomNeb - IDL/GDL Library for Atomic Data of Ionized Nebulae
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AtomNeb IDL Library

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AtomNeb-idl is a library written in Interactive Data Language (IDL)/GNU Data Language (GDL) for reading atomic data from AtomNeb, which is a database containing atomic data stored in the Flexible Image Transport System (FITS) file format for collisionally excited lines and recombination lines typically observed in spectra of ionized gaseous nebulae. The AtomNeb database were generated for use in proEQUIB, pyEQUIB, and other nebular spectral analysis tools.

Collisionally Excited Lines

AtomNeb for collisionally excited lines contains sets of atomic datasets, which include energy levels (Ej), collision strengths (Ωij), and transition probabilities (Aij) of the most ions commonly observed in ionized nebulae.

The atomic datasets for collisionally excited lines are as follows:

Each dataset contains the following atomic data FITS files: AtomElj.fits for Energy Levels (Ej), AtomOmij.fits for Collision Strengths (Ωij), and AtomAij.fits for Transition Probabilities (Aij).

Recombination Lines

AtomNeb for recombination lines contains sets of effective recombination coefficients (αeff) of recombination lines of H I, He I, He II, C I, C II, C III, C VI, N II, N III, N IV, N V, N VI, N VII, O II, O III, O IV, O V, O VI, O VIII, and Ne II ions typically observed in ionized nebulae, as well as Branching ratios (Br) of O II and N II lines.

The atomic datasets for recombination lines are as follows:


Dependent IDL Packages

This package requires the following packages:

  • To get this package with all the dependent packages, you can simply use git command as follows:

    git clone --recursive
  • If you plan to use the recent O II recombination coefficients (Storey, Sochi and Bastin 2017), you need to unpack them:

    cd AtomNeb-idl/atomic-data-rc/
    tar -xvf *.fits.tar.gz

Installation in IDL

  • To install the AtomNeb database and its API library in the Interactive Data Language (IDL), you need to add the path of this package directory to your IDL path. or more information about the path management in IDL, read the tips for customizing IDL program path provided by Harris Geospatial Solutions or the IDL library installation note by David Fanning in the Coyote IDL Library.
  • This package requires IDL version 7.1 or later.

Installation in GDL

  • You can install the GNU Data Language (GDL) if you do not have it on your machine:

    • Linux (Fedora):

      sudo dnf install gdl
    • Linux (Ubuntu):

      sudo apt-get install gnudatalanguage
    • OS X:

      brew install gnudatalanguage
    • Windows: You can use the GNU Data Language for Win32 (Unofficial Version) or you can compile the GitHub source using Visual Studio 2015 as shown in appveyor.yml.

  • To install the AtomNeb database and its API library in GDL, you need to add the path of this package directory to your .gdl_startup file in your home directory:

    !PATH=!PATH + ':/home/AtomNeb-idl/pro/'
    !PATH=!PATH + ':/home/AtomNeb-idl/externals/astron/pro/'

    You may also need to set GDL_STARTUP if you have not done in .bashrc (bash):

    export GDL_STARTUP=~/.gdl_startup

    or in .tcshrc (cshrc):

    setenv GDL_STARTUP ~/.gdl_startup
  • This package requires GDL version 0.9.8 or later.


For more information on how to use the API functions from the AtomNeb IDL libray, please read the API Documentation published on


  • Danehkar, A. (2019). AtomNeb: IDL Library for Atomic Data of Ionized Nebulae. J. Open Source Softw., 4, 898. doi:10.21105/joss.00898
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