Cutouts

Everything related to cutouts is documented bellow:

hostphot.cutouts.query_ps1(ra, dec, size=3, filters=None)

Query ps1filenames.py service to get a list of images

Parameters

  • ra (float) – Right Ascension in degrees.

  • dec (float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters to use. If None, uses grizy.

Returns

table – Astropy table with the results.

Return type

astropy Table

hostphot.cutouts.get_PS1_urls(ra, dec, size=3, filters=None)

Get URLs for images obtained with query_ps1().

Parameters

  • ra (float) – Right Ascension in degrees.

  • dec (float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters to use. If None, uses grizy.

Returns

url_list – List of URLs for the fits images.

Return type

list

hostphot.cutouts.get_PS1_images(ra, dec, size=3, filters=None)

Gets PS1 fits images for the given coordinates and filters.

Parameters

  • ra (float) – Right Ascension in degrees.

  • dec (float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters to use. If None, uses grizy.

Returns

fits_files – List of fits images.

Return type

list

hostphot.cutouts.get_DES_urls(ra, dec, fov, filters='grizY')

Obtains the URLs of the DES images+weights with the largest exposure times in the given filters.

Parameters

  • ra (float) – Right ascension in degrees.

  • dec (float) – Declination in degrees.

  • fov (float) – Field of view in degrees.

  • filters (str, default None) – Filters to use. If None, uses grizY.

Returns

  • url_list (list) – List of URLs with DES images.

  • url_w_list (list) – List of URLs with DES images weights.

hostphot.cutouts.get_DES_images(ra, dec, size=3, filters=None)

Gets DES fits images for the given coordinates and filters.

Parameters

  • ra (float) – Right Ascension in degrees.

  • dec (float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters to use. If None, uses grizY.

Returns

hdu_list – List of fits images.

Return type

list

hostphot.cutouts.get_SDSS_images(ra, dec, size=3, filters=None)

Downloads a set of SDSS fits images for a given set of coordinates and filters using SkyView.

Parameters

  • ra (str or float) – Right ascension in degrees.

  • dec (str or float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters to use. If None, uses ugriz.

Returns

hdu_list – List with fits images for the given filters. None is returned if no image is found.

Return type

list

hostphot.cutouts.match_wcs(fits_files)

Matches the WCS of all the images, taking the first ones as a reference.

Parameters

fits_files (list) – List of fits files.

Returns

matched_fits_files – List of fits files with matched WCS.

Return type

list

hostphot.cutouts.download_images(name, ra, dec, size=3, filters=None, overwrite=False, survey='PS1', version=None)

Download images for a given object in the given filters of a given survey.

Parameters

  • name (str) – Name used for tracking the object in your local directory.

  • ra (float) – Right ascension in degrees.

  • dec (float) – Declination in degrees.

  • size (float or ~astropy.units.Quantity, default 3) – Image size. If a float is given, the units are assumed to be arcmin.

  • filters (str, default None) – Filters for the images.

  • overwrite (bool, default False) – If True, the images are overwritten if they already exist.

  • survey (str, default PS1) – Survey used to download the images.

  • version (str, default None) – Version used by some surveys including multiple surveys. E.g. VHS for VISTA.

Examples

>>> from hostphot.cutouts import download_images
>>> name = 'SN2004eo'
>>> host_ra, host_dec = 308.2092, 9.92755  # coords of host galaxy of SN2004eo
>>> survey = 'PS1'
>>> download_images(name, host_ra, host_dec, survey=survey)
hostphot.cutouts.pool_download(df=None, name=None, ra=None, dec=None, size=600, filters=None, overwrite=False, survey='PS1', processes=8)

Downloads images for multiple objects using parallelisation.

Parameters

  • df (DataFrame, default None) – DataFrame with the values of the argmuents. If this is given, name, ra and dec should be the names of the columns in df.

  • name (str or list-like, default None) – Name used for tracking the object in your local directory.

  • ra (float or list-like, default None) – Right ascension in degrees of the center of the image.

  • dec (float or list-like, default None) – Declination in degrees of the center of the image.

  • size (int, default 600) – Image size in pixels.

  • filters (str, default None) – Filters for the images. If None, use all the available filters.

  • overwrite (bool, default False) – If True, the images are overwritten if they already exist.

  • survey (str, default PS1) – Survey used to download the images

  • processes (floar, default 8) – Number of processes to use for the parallelisation.