Package: pygedm
PyGEDMPython bindings for the YMW16, NE2001 and YT2020 electron density modelsThis package is a Python interface to the YMW16 and NE2001 electron density models, and YT2020 halo model.
The Yao, Manchester and Wang (2017,Astrophys. J., 835, 29;arXiv:1610.09448) YMW16 electron density model, is written in C++, and the Cordes and Lazio
(2001,arXiv:0207156) NE2001 model is written in FORTRAN. This package, PyGEDM, wraps these
two codes usingpybind11to make them usable from Python. Here, we have converted NE2001 to C++ usingf2c.Web appWe provide a web app athttps://apps.datacentral.org.au/pygedm/The pygedm web app is kindly hosted byData Central.UsageSome usage examples can be found in theexamples directory.importpygedm# calculate DM at a given distanceDM,tau_sc=pygedm.dist_to_dm(204.0,-6.5,200,method='ne2001')DM,tau_sc=pygedm.dist_to_dm(204.0,-6.5,200,method='ymw16')# calculate distance for a given sky position and DMdist,tau_sc=pygedm.dm_to_dist(123.4,4.0,200)# calculate N_e density at xyz galactocentric coordinatesne=pygedm.calculate_electron_density_xyz(1.0,2.0,3.0)# calculate N_e density at Galactic lat/long/distance coordsne=pygedm.calculate_electron_density_lbr(204.0,-6.5,3000.0)# Calculate halo DM contributiondm_halo=pygedm.calculate_halo_dm(gl=0,gb=30)The methods return astropyQuantities, which have units attached, and can accept astropyAnglesand Quantities as arguments:importpygedmimportastropy.unitsasuimportastropy.coordinatesascDM=u.Quantity(10.0,unit='pc cm^-3')ra,dec=c.Angle(23.0,unit='hourangle'),c.Angle('-43:00:02',unit='degree')sky_coords=c.SkyCoord(ra,dec,frame='icrs')dist,tau_sc=pygedm.dm_to_dist(sky_coords.galactic.l,sky_coords.galactic.b,DM)print(dist.to('lyr'))>>3362.16343117lyrprint(tau_sc.to('ns'))>>7.758686138nsInstallationRequirespybind11,astropy,numpy,scipy, a newish C compiler with C++11 support (Ubuntu 16.04+ default gcc will work), plusf2c.Pre-compiled wheels are generated for linux, meaning you can skip thef2cinstall step. Alternatively you can install viaapt-get f2cin Ubuntu, or  viaconda install -c conda-forge f2cif you use conda.For MacOS, you are best off usingcondaand gettingf2cviaconda install -c conda-forge f2c. Windows is not currently supported.You should be able to install with:pip install pygedmorpip install git+https://github.com/telegraphic/pygedmto install the latest version from github. Alternatively, download this repository and install viapip install .To run unit tests, runpython setup.py test. Note that these tests only check the Python bindings,
not the underlying C/FORTRAN source code (which is not supplied with unit tests).ReferencesIf using PyGEDM in a journal article, please remember to cite the underlying electron density models:Cordes, J. M., & Lazio, T. J. W. (2002),NE2001.I. A New Model for the Galactic Distribution of Free Electrons and its Fluctuations,
arXiv e-prints, astro-ph/0207156.Cordes, J. M., & Lazio, T. J. W. (2003),NE2001. II. Using Radio Propagation Data to Construct a Model for the Galactic Distribution of Free Electrons,
arXiv e-prints, astro-ph/0301598.Yao, J. M., Manchester, R. N., & Wang, N. (2017),A New Electron-density Model for Estimation of Pulsar and FRB Distances,
The Astrophysical Journal, Volume 888, Issue 2, id.105, Colume 835, id.29Yamasaki, S., & Totani, T. (2020),The Galactic Halo Contribution to the Dispersion Measure of Extragalactic Fast Radio Bursts,
The Astrophysical Journal, Volume 888, Issue 2, id.105These are available in bibtex format inreferences.bib,
and also as anADS library.YMW16 C READMEYMW16 is a model for the distribution of free electrons in the Galaxy,
the Magellanic Clouds and the inter-galactic medium, that can be used
to estimate distances for real or simulated pulsars and fast radio
bursts (FRBs) based on their position and dispersion measure.The Galactic model is based on 189 pulsars that have independently
determined distances as well as dispersion measures, whereas simpler
models are used for the electron density in the MC and the IGM. It is
estimated that the 95% of predicted Galactic pulsar distances will
have a relative error of less than a factor of 0.9. Pulse broadening
due to scattering in the Galactic interstellar medium, the Magellanic
Clouds, the intergalactic medium and FRB host galaxies is estimated.As well as the ymw16 dm-distance program, we also provide a program,
ymw16_ne, which gives the electron density at any point in the Galaxy
or Magellanic Clouds.A paper (Yao, Manchester and Wang, 2017,Astrophys. J., 835, 29;arXiv:1610.09448) describes the model and compares its predictions
with those of earlier Galactic electron density models. YMW16 is the
first electron-density model to estimate extragalactic pulsar
distances and FRB distances.To make a command-line executable version of the program, download and
unpack the latest version of the program. Then run "make_ymw16" to
create the executable. The environment variable YMW16_DIR may be set
up to point at a directory containing ymw16par.txt and
spiral.txt. Access to these files is needed at runtime.Websites allowing interactive access to the YMW16 distance model and
download of the latest program version are available at:http://www.xao.ac.cn/ymw16/,http://www.atnf.csiro.au/research/pulsar/ymw16/andhttps://bitbucket.org/psrsoft/ymw16/.Please report any issues or bugs athttps://bitbucket.org/psrsoft/ymw16/issues/new/or directly to the
authors. Please provide an example illustrating the problem.YMW16 C LICENSECopyright (C) 2016, 2017  J. M. Yao, R. N. Manchester, N. Wang.

YMW16 is free software: you can redistribute it and/or modify　it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

YMW16 is distributed in the hope that it will be useful,　but WITHOUT
ANY WARRANTY; without even the implied warranty of　MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the　GNU General Public License,
available at http://www.gnu.org/licenses/, for more details.

Jumei Yao (yaojumei _@_ xao.ac.cn), Richard N Manchester
(dick.manchester _@_ csiro.au), Na Wang (na.wang _@_ xao.ac.cn)NE2001 README07 July 2002
To compile and execute the code,  seecode.pdf.