Source code for dustmaps.csfd

#!/usr/bin/env python
# Reads the "Corrected SFD" dust reddening map of Chiang (2023).
# Copyright (C) 2023  Gregory M. Green
# This program 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 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

from __future__ import print_function, division

import os
import numpy as np
import healpy as hp
import as fits
import astropy.units as units

from .std_paths import *
from .healpix_map import HEALPixQuery
from . import fetch_utils
from . import dustexceptions

[docs]class CSFDQuery(HEALPixQuery): """ Queries the Corrected SFD dust map of Chiang (2023). This map is based on SFD, but contains a correction to remove contamination from large-scale structure (i.e., external galaxies). """
[docs] def __init__(self, map_fname=None, mask_fname=None): """ Args: map_fname (Optional[:obj:`str`]): Filename of the CSFD EBV map. Defaults to ```None``, meaning that the default location is used. mask_fname (Optional[:obj:`str`]): Filename of the CSFD mask map. Defaults to ```None``, meaning that the default location is used. """ if map_fname is None: map_fname = os.path.join(data_dir(), 'csfd', 'csfd_ebv.fits') if mask_fname is None: mask_fname = os.path.join(data_dir(), 'csfd', 'mask.fits') try: with as hdulist: ebv_data = hdulist['xtension'].data[:]['T'].flatten() with as hdulist: mask_data = hdulist['xtension'].data[:]['T'].flatten() except IOError as error: print(dustexceptions.data_missing_message('csfd', 'CSFD (Chiang 2023)')) raise error super(CSFDQuery, self).__init__(ebv_data, False, 'galactic', flags=mask_data)
[docs] def query(self, coords, **kwargs): """ Returns CSFD reddening on the same scale as SFD (similar to E(B-V)) at the specified location(s) on the sky. Also optionally returns a bit mask, where the bits (ordered from least to most significant) have the following meanings:: Bit 0: 'LSS_corr' - This bit is set in the footprint within which the LSS is reconstructed, and CSFD = SFD - LSS (otherwise CSFD = SFD). Bit 1: 'no_IRAS' - Set in the area with no IRAS data (DIRBE data filled in SFD); LSS removal in CSFD is done using a 1 deg smoothed LSS. Bit 2: 'cosmology' - Set in the area where both the LSS and CSFD are most reliable for precision cosmology analyses. Args: coords (:obj:`astropy.coordinates.SkyCoord`): The coordinates to query. return_flags (Optional[:obj:`bool`]): If ``True``, then a bit mask is returned as well, indicating where CSFD has been corrected for large-scale structure, where IRAS data was used, and where the map is suitable for cosmology. See above description of bits. Defaults to ``False``. Returns: A float array of the reddening, at the given coordinates. The shape of the output is the same as the shape of the input coordinate array, ``coords``. If ``return_flags`` is ``True``, a second array (a bit mask) of the same shape is returned. See above description of the meaning of each bit. """ return super(CSFDQuery, self).query(coords, **kwargs)
[docs]def fetch(clobber=False): """ Downloads the Corrected SFD dust map of Chiang (2023). Args: clobber (Optional[bool]): If ``True``, any existing file will be overwritten, even if it appears to match. If ``False`` (the default), ``fetch()`` will attempt to determine if the dataset already exists. This determination is not 100\% robust against data corruption. """ file_spec = [ ('csfd_ebv.fits', '31cd2eec51bcb5f106af84a610ced53c'), ('mask.fits', '9142f5a5d184125836a68b6f48d1113f') ] for fn,md5sum in file_spec: fname = os.path.join(data_dir(), 'csfd', fn) # Download from Zenodo url = '{}'.format(fn) fetch_utils.download_and_verify(url, md5sum, fname, clobber=clobber)