hostphot 0.2.0

Photometry (local and global) for host galaxy of supernovae

HostPhot

Conda environment

It is recommended to create an environment for every new project:

conda create -n hostphot pip
conda activate hostphot
pip install hostphot

Modules

Cutouts

This module allows you to download image cutouts from PS1, DES and SDSS. For this, you can use get_PS1_images(), get_DES_images() and get_SDSS_images(), respectively. For example:

from hostphot.cutouts import get_PS1_images

ra, dec = 30, 100
size = 400  # in pixels
filters = 'grizy'

fits_images = get_PS1_images(ra, dec, size, filters)

where fits_images is a list with the fits images in the given filters.

You can also use download_multiband_images() for multiple images:

from hostphot.cutouts import download_multiband_images

download_multiband_images(sn_name, ra, dec, size,
                                work_dir, filters,
                                  overwrite, survey)

where work_dir is where all the images will be downloaded. A Subdirectory inside work_dir will be created with the SN name as the directory name.

Local Photometry

Local photometry can be obtained for the downloaded images. For this, use extract_local_photometry() for a single image:

from hostphot.local_photometry import extract_local_photometry

fits_file = 'path/to/local/fits_file'
ra, dec = 30, 100
z = 0.01  # redshift
ap_radius = 4  # aperture for the photometry in kpc
survey = 'PS1'

extract_local_photometry(fits_file, ra, dec, z, ap_radius, survey)

which returns mag and mag_err. You can also use multi_local_photometry() for multiple images:

from hostphot.local_photometry import multi_local_photometry

multi_local_photometry(name_list, ra_list, dec_list, z_list,
                             ap_radius, work_dir, filters,
                               survey, correct_extinction)

where work_dir should be the same as used in download_multiband_images() and name_list should contain the names of the SNe used in download_multiband_images() as well. This produces a pandas DataFrame as an output where, e.g., column g is the g-band magnitude and g_err its uncertainty.

Global Photometry

Global photometry can be obtained in a similar way to local photometry. Use extract_global_photometry() for a single image:

from hostphot.global_photometry import extract_global_photometry

survey = 'PS1'

extract_global_photometry(fits_file, host_ra, host_ra, survey=survey)

which returns mag and mag_err. You can also use multi_global_photometry() for multiple images:

from hostphot.global_photometry import multi_global_photometry

survey = 'PS1'
correct_extinction = True

multi_global_photometry(name_list, host_ra_list, host_dec_list, work_dir, filters,
                               survey=survey, correct_extinction=correct_extinction)