Source code for skysurvey.effects.milkyway

"""
This module provides utilities and model for Milky Way dust extinction.
"""

from astropy.coordinates import SkyCoord




def get_mwebv(ra, dec, which="planck"):
    """ Get the Milky Way E(B-V) extinction parameter for input coordinates.

    This is based on `dustmaps`. 
    If this is the first time you use it, you may have to download the maps 
    first (instructions will be given).
    
    Parameters
    ----------
    ra, dec: float, array
        Coordinates.

    which: str
        Name of the dustmap to use.
        - `planck`: Planck (2013)
        - `sfd`: Schlegel, Finkbeiner & Davis (1998)

    Returns
    -------
    array
        E(B-V) values.
    """
    if which.lower() == "planck":
        from dustmaps.planck import PlanckQuery as dustquery
    elif which.lower() == "sfd":
        from dustmaps.sfd import SFDQuery as dustquery
    else:
        raise NotImplementedError("Only Planck and SFD maps implemented")
        
    coords = SkyCoord(ra, dec, unit="deg")
    return dustquery()(coords) # Instanciate and call.



mwebv_model = {"mwebv": {"func": get_mwebv,
                         "kwargs":{"ra":"@ra", "dec":"@dec"}}
              }