HiPS2fits Service (astroquery.hips2fits)

Getting started

Query the CDS hips2fits service

The CDS hips2fits service offers a way to extract FITS images from HiPS sky maps. HiPS is an IVOA standard that combines individual images in order to produce a progressive hierarchical sky map describing the whole survey. Please refer to the IVOA paper for more info.

Given an astropy user-defined WCS with a HiPS name, hips2fits will return you the corresponding FITS image (JPG/PNG output formats are also implemented).

See the list of valid HiPS names hosted in CDS here. It is also possible to use astroquery.cds.CdsClass.find_datasets() to retrieve the list of HiPSes matching an expression (e.g. *HST* will return the names of the HST surveys HiPSes).

This package implements two methods:

  • query_with_wcs() extracting a FITS image from a HiPS and an astropy wcs.WCS.

    See here all the valid HiPS names hosted in CDS.

  • query() extracting a FITS image from a HiPS given the output image pixel size, the center of projection, the type of projection and the field of view.

    See here all the valid HiPS names hosted in CDS.

Examples

With a user defined astropy WCS

>>> from astroquery.hips2fits import hips2fits
>>> import matplotlib.pyplot as plt
>>> from matplotlib.colors import Colormap
>>> from astropy import wcs as astropy_wcs
>>> # Create a new WCS astropy object
>>> w = astropy_wcs.WCS(header={
...     'NAXIS1': 2000,         # Width of the output fits/image
...     'NAXIS2': 1000,         # Height of the output fits/image
...     'WCSAXES': 2,           # Number of coordinate axes
...     'CRPIX1': 1000.0,       # Pixel coordinate of reference point
...     'CRPIX2': 500.0,        # Pixel coordinate of reference point
...     'CDELT1': -0.18,        # [deg] Coordinate increment at reference point
...     'CDELT2': 0.18,         # [deg] Coordinate increment at reference point
...     'CUNIT1': 'deg',        # Units of coordinate increment and value
...     'CUNIT2': 'deg',        # Units of coordinate increment and value
...     'CTYPE1': 'GLON-MOL',   # galactic longitude, Mollweide's projection
...     'CTYPE2': 'GLAT-MOL',   # galactic latitude, Mollweide's projection
...     'CRVAL1': 0.0,          # [deg] Coordinate value at reference point
...     'CRVAL2': 0.0,          # [deg] Coordinate value at reference point
... })
>>> hips = 'CDS/P/DSS2/red'
>>> result = hips2fits.query_with_wcs(
...    hips=hips,
...    wcs=w,
...    get_query_payload=False,
...    format='jpg',
...    min_cut=0.5,
...    max_cut=99.5,
...    cmap=Colormap('viridis'),
... )
>>> im = plt.imshow(result)
>>> plt.show(im)
../_images/query_wcs.png

Without WCS

>>> from astroquery.hips2fits import hips2fits
>>> import matplotlib.pyplot as plt
>>> from matplotlib.colors import Colormap
>>> import astropy.units as u
>>> from astropy.coordinates import Longitude, Latitude, Angle
>>> hips = 'CDS/P/DSS2/red'
>>> result = hips2fits.query(
...    hips=hips,
...    width=1000,
...    height=500,
...    ra=Longitude(0 * u.deg),
...    dec=Latitude(20 * u.deg),
...    fov=Angle(80 * u.deg),
...    projection="AIT",
...    get_query_payload=False,
...    format='jpg',
...    min_cut=0.5,
...    max_cut=99.5,
...    cmap=Colormap('viridis'),
... )
>>> im = plt.imshow(result)
>>> plt.show(im)
../_images/query_no_wcs.png

Reference/API

astroquery.hips2fits Package

CDS hips2fits Query Tool

Author

Matthieu Baumann (matthieu.baumann@astro.unistra.fr)

This package is for querying the CDS hips2fits service, primarily hosted at:

Note: If the access to hips2fits was helpful for your research work, the following acknowledgment would be appreciated:

This research has made use of the hips2fits, a tool developed at CDS, Strasbourg, France aiming at extracting
FITS images from HiPS sky maps with respect to a WCS.

Classes

hips2fitsClass(*args)

Query the CDS hips2fits service

Conf()

Configuration parameters for astroquery.template_module.