Contents

Overview

docs
tests

Python implementation of Cordes-Lazio’s NE2001 Galactic Free Electron Density Model. BEWARE: The code as implemented in FORTRAN differs in several ways from the 2003 posting (astro-ph/0301598: http://adsabs.harvard.edu/abs/2003astro.ph..1598C ). See the docs for details.

• Free software: BSD license

Development

To run the all tests run:

tox

Note, to combine the coverage data from all the tox environments run:

Windows	set PYTEST_ADDOPTS=--cov-append tox
Other	PYTEST_ADDOPTS=--cov-append tox

Installation

At the command line:

pip install ne2001

Dependencies

ne2001 depends on the following list of Python packages.

We recommend that you use Anaconda to install and/or update these packages.

• python versions 2.7, or 3.4 or later
• numpy version 1.11 or later
• astropy version 1.3 or later
• scipy version 0.17 or later

If you are using Anaconda, you can check the presence of these packages with:

conda list "^python|numpy|astropy|scipy"

Code

This document describes the code.

NE2001

Overall, the current implementation is a nearly direct port of the FORTRAN code created and kindly provide by Cordes & Lazio (astro-ph/3101598)

It is important to appreciate, however, that the code is not fully consistent with the detailed description provided in the publication. These are the key differences:

• The electron density near the Galactic Center is a constant value
• In NE2001, the thin disk assumes a height of 1.8kpc instead of the A2 parameter
• In NE2001, the Galactic parameters are substantially different than those in the posting

In addition, we have made a few modifications of our own:

• In the original NE2001 code for clumps, q2 <= 5 is used instead of q <= 5.

Parameters

Components of the Galactic ISM are parameterized in terms of size, central electron density, etc.

Currently, the code reads the parameters from the JSON file data/ne2001_params.json. You can modify this directly and future code will allow easier manipulation.

v0.1

Here is the JSON file:

{
    "version": "v0.1 by JXP on 05March2017",
    "galactic_center": {
        "F": 60000.0,
        "center": [
            -0.01,
            0.0,
            -0.02
        ],
        "e_density": 10.0,
        "height": 0.026,
        "radius": 0.145
    },
    "ldr": {
        "F": 0.1,
        "center": [
            1.36,
            8.06,
            0.0
        ],
        "e_density": 0.012,
        "ellipsoid": [
            1.5,
            0.75,
            0.5
        ],
        "theta": -0.4223696789826278
    },
    "lhb": {
        "F": 0.01,
        "center": [
            0.01,
            8.45,
            0.17
        ],
        "cylinder": [
            0.085,
            0.1,
            0.33
        ],
        "e_density": 0.005,
        "theta": 0.2617993877991494
    },
    "loop_in": {
        "F": 0.2,
        "center": [
            -0.045,
            8.4,
            0.07
        ],
        "e_density": 0.0125,
        "radius": 0.12
    },
    "loop_out": {
        "F": 0.01,
        "center": [
            -0.045,
            8.4,
            0.07
        ],
        "e_density": 0.0125,
        "radius": 0.18
    },
    "lsb": {
        "F": 0.01,
        "center": [
            -0.75,
            9.0,
            -0.05
        ],
        "e_density": 0.016,
        "ellipsoid": [
            1.05,
            0.425,
            0.325
        ],
        "theta": 2.426007660272118
    },
    "spiral_arms": {
        "e_density": 1.0,
        "F": 1.0
    },
    "thick_disk": {
        "F": 0.18,
        "e_density": 0.034020618556701035,
        "height": 0.97,
        "radius": 17.5
    },
    "thin_disk": {
        "F": 120,
        "e_density": 0.08,
        "height": 0.15,
        "radius": 3.8
    }
}

Usage

Overview

To use ne2001 in a project:

import ne2001

Simple Calculations

Here is an example for calculating the DM along a Galactic sightline to a distance of 20kpc:

from ne2001 import io as ne_io
PARAMS = ne_io.read_params()
ne = density.ElectronDensity(**PARAMS)
l, b  = 0., 90.
DM = ne.DM(l, b, 20.)

Scripts

This document describes the scripts packaged with ne2001.

ne2001_lb

Calculate quantities along an input Galactic line-of-sight. Main inputs are longitude and latitude. Here is the usage:

ne2001_lb -h
usage: ne2001_lb [-h] [-d D] l b

Calculate quantities along a Galactic sightline v0.1

positional arguments:
  l           Galactic longitude (deg)
  b           Galactic latitude (deg)

optional arguments:
  -h, --help  show this help message and exit
  -d D        Distance (kpc)

Currently, this script calculates the DM along the sightline to a default distance of 100 kpc.

Reference

ne2001

Contributing

Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.

Bug reports

When reporting a bug please include:

• Your operating system name and version.
• Any details about your local setup that might be helpful in troubleshooting.
• Detailed steps to reproduce the bug.

Documentation improvements

ne2001 could always use more documentation, whether as part of the official ne2001 docs, in docstrings, or even on the web in blog posts, articles, and such.

Feature requests and feedback

The best way to send feedback is to file an issue at https://github.com/benbaror/ne2001/issues.

If you are proposing a feature:

• Explain in detail how it would work.
• Keep the scope as narrow as possible, to make it easier to implement.
• Remember that this is a volunteer-driven project, and that code contributions are welcome :)

Development

To set up ne2001 for local development:

1. Fork ne2001 (look for the “Fork” button).

2. Clone your fork locally:

   git clone git@github.com:your_name_here/ne2001.git
   

3. Create a branch for local development:

   git checkout -b name-of-your-bugfix-or-feature
   

   Now you can make your changes locally.

4. When you’re done making changes, run all the checks, doc builder and spell checker with tox one command:

   tox
   

5. Commit your changes and push your branch to GitHub:

   git add .
   git commit -m "Your detailed description of your changes."
   git push origin name-of-your-bugfix-or-feature
   

6. Submit a pull request through the GitHub website.

Pull Request Guidelines

If you need some code review or feedback while you’re developing the code just make the pull request.

For merging, you should:

1. Include passing tests (run tox) [1].
2. Update documentation when there’s new API, functionality etc.
3. Add a note to CHANGELOG.rst about the changes.
4. Add yourself to AUTHORS.rst.

[1]	If you don’t have all the necessary python versions available locally you can rely on Travis - it will run the tests for each change you add in the pull request. It will be slower though ...

Tips

To run a subset of tests:

tox -e envname -- py.test -k test_myfeature

To run all the test environments in parallel (you need to pip install detox):

detox

Authors

• Ben Bar-Or -
• 10. Xavier Prochaska -

Changelog

0.0.1 (‘’)

• First release on PyPI.

0.0.2 (‘Not released yet’)

• Add simple_lb script
• Add units

Indices and tables

• Index
• Module Index
• Search Page