PolarizerTables
- class acstools.polarization_tools.PolarizerTables(input_dict)
Bases:
objectA class for holding all of the polarization tables (as astropy tables) in attributes. These attributes are:
wfc_transmission: Transmission and leak correction factors for computing ACS/WFC fractional polarization.
hrc_transmission: Transmission and leak correction factors for computing ACS/HRC fractional polarization.
wfc_efficiency: Efficiencies of the ACS/WFC polarizers for computing Stokes parameters.
hrc_efficiency: Efficiencies of the ACS/HRC polarizers for computing Stokes parameters.
Note
The default table contained within the acstools package uses average transmission leak correction terms for a source with a spectrum flat in wavelength space.
Polarizer calibration information can be read from the default YAML file contained in the acstools package, or from a user-supplied YAML file using the class methods
from_yaml()andfrom_package_data(). The YAML file format is:transmission: meta: dictionary of metadata detector: filter: list of ACS filters t_para: list of parallel transmissions for each filter t_perp: list of perpendicular transmissions for each filter correction: list of transmission leak correction factors for each filter efficiency: meta: dictionary of metadata detector: filter: list of ACS filters pol0: list of POL0 coefficients matching each filter pol60: list of POL60 coefficients matching each filter pol120: list of POL120 coefficients matching each filter
The meta elements will pass a dictionary of metadata to the output tables. Any metadata can be included, but at minimum a description of the origin of the table values should be provided. Multiple detectors can be contained in a single YAML file. An example is shown below:
transmission: meta: {'description': 'Descriptive message.'} wfc: filter: ['F475W', 'F606W'] t_para: [0.42, 0.51] t_perp: [0.0, 0.0] correction: [1.0, 1.0] hrc: filter: ['F330W'] t_para: [0.48] t_perp: [0.05] correction: [1.21] efficiency: meta: {'description': 'Descriptive message.'} wfc: filter: ['F475W', 'F606W'] pol0: [1.43, 1.33] pol60: [1.47, 1.36] pol120: [1.42, 1.30] hrc: filter: ['F330W'] pol0: [1.73] pol60: [1.53] pol120: [1.64]
- Parameters:
input_dict (dict) –
Examples
To use the default values supplied in the acstools package (which come from the ACS Data Handbook section 5.3):
>>> from acstools.polarization_tools import PolarizerTables >>> tables = PolarizerTables.from_package_data() >>> print(tables.wfc_efficiency) filter pol0 pol60 pol120 ------ ------ ------ ------ F475W 1.4303 1.4717 1.4269 F606W 1.3314 1.3607 1.3094 F775W 0.9965 1.0255 1.0071
To supply your own YAML file of the appropriate format:
>>> from acstools.polarization_tools import PolarizerTables >>> tables = PolarizerTables.from_yaml('data/polarizer_tables.yaml') >>> print(tables.wfc_transmission) filter t_para t_perp correction ------ ------------------ ---------------------- ------------------ F475W 0.4239276798513098 0.00015240583841551956 1.000719276691027 F606W 0.5156734594049419 5.5908749369641956e-05 1.000216861312415 F775W 0.6040891283746557 0.07367364117759412 1.2777959654493372
>>> print(tables.wfc_transmission.meta['description']) WFC filters use MJD corresponding to 2020-01-01. HRC filters use MJD corresponding to 2007-01-01.
Methods Summary
Use the YAML file contained within the acstools package to retrieve the polarizer calibration data.
from_yaml(yaml_file)Read in a YAML file containing polarizer calibration data.
Methods Documentation
- classmethod from_package_data()
Use the YAML file contained within the acstools package to retrieve the polarizer calibration data.
- Returns:
pol_tables
- Return type:
PolarizerTables