Filter Photometry

The following Filter and Wheel classes can be used to simulate coronagraph observations in imaging mode.

class coronagraph.imager.Filter(name=None, bandcenter=None, FWHM=None, wl=None, response=None, notes='')

Filter for telescope imaging mode.

Parameters
  • name (string) – Name of filter

  • bandcenter (float) – Wavelength at bandcenter (um)

  • FWHM (float) – Full-width as half-maximum (um)

  • wl (array) – Wavelength grid for response function (um)

  • response (array) – Filter response function

  • notes (string) – Notes of filter, e.g. ‘Johnson-Cousins’

class coronagraph.imager.Wheel

Filter Wheel. Contains different filters as attributes.

add_new_filter(filt, name='new_filter')

Adds new filter to wheel

Parameters
  • filt (Filter) – New Filter object to be added to wheel

  • name (string (optional)) – Name to give new filter attribute

plot(ax=None, ylim=None)

Plot the filter response functions

Parameters

ax (matplotlib.axis (optional)) – Axis instance to plot on

Returns

ax – Axis with plot

Return type

matplotlib.axis

Note

Only returns an axis if an axis was not provided.

coronagraph.imager.read_jc()

Read and parse the Johnson-Cousins filter files.

Returns

  • filters (numpy.ndarray) – Array of filter response functions

  • filter_names (list) – List of string names for the filters

  • bandcenters (numpy.array) – Wavelength bandcenters for the filters [microns]

  • FWHM (numpy.array) – Full-width at half max for the filters

class coronagraph.imager.johnson_cousins

Instantiate a filter Wheel with the Johnson-Cousins filters (U, B, V, R, I).

Example

>>> jc = cg.imager.johnson_cousins()
>>> jc.plot(ylim = (0.0, 1.2))
coronagraph.imager.read_landsat()

Read and parse the LANDSAT filter files.

Returns

  • wl (list) – List of wavelength grids for each filter [microns]

  • response (list) – Filter responses for each filter

  • LANDSAT_names (list) – Names of each LANDSAT filter

  • FWHM (numpy.array) – Full-width at half max for the filters

  • bandcenters (numpy.array) – Wavelength bandcenters for the filters [microns]

class coronagraph.imager.landsat

Instantiate a filter Wheel with the LANDSAT filters.

coronagraph.imager.read_jc2()

Read and parse the Johnson-Cousins Bessel filter files.

Returns

  • filters (numpy.ndarray) – Array of filter response functions

  • filter_names (list) – List of string names for the filters

  • bandcenters (numpy.array) – Wavelength bandcenters for the filters [microns]

  • FWHM (numpy.array) – Full-width at half max for the filters

class coronagraph.imager.johnson_cousins2

Instantiate a filter Wheel with the Johnson-Cousins Bessel filters (U, B, V, R, I).