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https://github.com/ruizca/gdpyc

Gas and Dust Python Calculator
https://github.com/ruizca/gdpyc

astronomy astronomy-library dust extinction python27 python3 reddening xray

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Gas and Dust Python Calculator

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README 

        
gdpyc ─ Gas and Dust Python Calculator

======================================

.. inclusion-marker-main-readme



``gdpyc`` is a Python 2/3 package for calculating Hydrogen column density

and optical extinction. ``gdpyc`` offers functionalities similar

to the `nh tool`_ included in HEASoft, or on-line web services like

HEASARC's `nH`_ or IRSA's `Galactic Dust Reddening and Extinction`_.



This package uses HEALpix maps provided by NASA's LAMBDA service. Please

cite the original papers and authors of the surveys if you use this tool

for your research (see sections Surveys and References below).



|astropy| |DOI|



Dependencies

------------

``gdpyc`` depends on:



* ``numpy`` 

* ``astropy``

* ``astropy-healpix``

* ``regions``



Certain functionalities also requiere:



* ``healpix``

* ``matplotlib``



Installation

------------



``gdpyc`` can be easily installed using ``pip``::



    pip install gdpyc



Example

-------

A simple example of using ``gdpyc``::



    >>> from gdpyc import GasMap, DustMap

    >>> from astropy.coordinates import SkyCoord

    

    >>> coords = SkyCoord(34.0, -5.0, unit='deg')

    >>> GasMap.nh(coords, nhmap='DL')



    



    >>> GasMap.nh(coords, nhmap='LAB')



    



    >>> DustMap.ebv(coords, dustmap='Planck13')



    '0.027179038520908336'



    >>> DustMap.extinction(coords, dustmap='SFD', filters='SDSS_r')



    

           SDSS_r       

          float64       

    --------------------

    0.049108389441137615



    >>> GasMap.plot_map('HI4PI')



Surveys

-------

``gdpyc`` includes several HI and dust surveys with nH and E(B - V)

estimations. We created low resolution HEALPix maps for all surveys

(NSIDE=64 ~ 1 degree pixels) by degrading the original maps using

the `ud_grade` tool from `healpy`. Only low resolution maps are

included in the installation. If the user asks for high resolution

maps (`hires` parameter, see API documentation), they are downloaded

as needed and stored for future use.



HI surveys

^^^^^^^^^^



`DL`_: Composite all-sky map of neutral Hydrogen column density (NHI),

formed from the Leiden/Dwingeloo survey data [1]_ and the composite NHI

map of [2]_. The two datasets are not matched in sensitivity or resolution;

note that discontinuities exist in the constructed composite map. 



`DL high resolution data`_ (oversampled), NSIDE=512 ~ 0.11 deg.



`LAB`_: Observations of 21-cm emission from Galactic neutral Hydrogen

over the entire sky, merging the Leiden/Dwingeloo Survey [1]_ of the sky

north of -30° with the Instituto Argentino de Radioastronomia Survey

[3]_, [4]_ of the sky south of -25°. [5]_



`LAB high resolution data`_ (oversampled), NSIDE=512 ~ 0.11 deg. [6]_



`HI4PI`_: The HI 4-PI Survey (HI4PI) is a 21-cm all-sky survey of

neutral atomic Hydrogen. It is constructed from the Effelsberg-Bonn HI

Survey (EBHIS) and the Galactic All-Sky Survey (GASS). [7]_



`HI4PI high resolution data`_, NSIDE=1024 ~ 0.06 deg.



Dust surveys

^^^^^^^^^^^^

`SFD`_: All-sky map of Galactic reddening, E(B - V), from a

composite 100 micron map formed from IRAS/ISSA maps calibrated

using DIRBE observations. [8]_



`SFD high resolution data`_ (undersampled), NSIDE=512 ~ 0.11 deg.



`Planck13`_: All-sky map of Galactic reddening, E(B - V), using

Planck-HFI and IRAS data, for extra-galactic studies. [9]_



`Planck13 high resolution data`_, NSIDE=2048 ~ 0.03 deg.



Extinction values for different filters are estimated using the E(B - V)

conversion factors presented in [10]_, assuming an extinction to

reddening ratio R=3.1 Additional factors for 2MASS, `Spitzer`-IRAC

and WISE filters are from IRSA's `Galactic Dust Reddening and Extinction`_ 

service.



References

----------

.. [1] Hartmann & Burton 1997, Cambridge University Press.

.. [2] Dickey & Lockman 1990, Ann. Rev. A&A, 28, 215.

.. [3] Arnal et al. 2000, A&AS, 142.

.. [4] Bajaja et al. 2005, A&A, 440, 2

.. [5] Kalberla et al. 2005, A&A, 440, 775.

.. [6] Land & Slosar 2007, Phys. Rev. D, 76, 8.

.. [7] HI4PI Collaboration et al. 2016, A&A, 594, A116.

.. [8] Schlegel, Finkbeiner & Davis 1998, ApJ, 500, 2.

.. [9] Planck Collaboration et al. 2013, A&A, 571, A11.

.. [10] Schlafly & Finkbeiner 2011, ApJ, 737, 2, 103.



.. _nh tool: https://heasarc.gsfc.nasa.gov/lheasoft/ftools/heasarc.html

.. _nH: https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/w3nh/w3nh.pl

.. _Galactic Dust Reddening and Extinction: https://irsa.ipac.caltech.edu/applications/DUST/

.. _DL: https://lambda.gsfc.nasa.gov/product/foreground/fg_combnh_map.cfm

.. _DL high resolution data: https://lambda.gsfc.nasa.gov/product/foreground/fg_HI_get.cfm

.. _LAB: https://lambda.gsfc.nasa.gov/product/foreground/fg_LAB_HI_Survey_info.cfm

.. _LAB high resolution data: https://lambda.gsfc.nasa.gov/product/foreground/fg_LAB_HI_Survey_get.cfm

.. _HI4PI: https://lambda.gsfc.nasa.gov/product/foreground/fg_hi4pi_info.cfm

.. _HI4PI high resolution data: https://lambda.gsfc.nasa.gov/product/foreground/fg_hi4pi_get.cfm

.. _SFD: https://lambda.gsfc.nasa.gov/product/foreground/fg_ebv_map.cfm

.. _SFD high resolution data: https://lambda.gsfc.nasa.gov/product/foreground/fg_sfd_get.cfm

.. _Planck13: https://wiki.cosmos.esa.int/planckpla/index.php/CMB_and_astrophysical_component_maps#Thermal_dust_emission

.. _Planck13 high resolution data: http://pla.esac.esa.int/pla/aio/product-action?MAP.MAP_ID=HFI_CompMap_ThermalDustModel_2048_R1.20.fits



.. |astropy| image:: http://img.shields.io/badge/powered%20by-AstroPy-orange.svg?style=flat

   :target: http://www.astropy.org/



.. |DOI| image:: https://zenodo.org/badge/156710074.svg

   :target: https://zenodo.org/badge/latestdoi/156710074