Channel#

class aiapy.response.Channel(channel: Unit('Angstrom'), *, instrument_file=None)[source]#

Bases: object

Interface to AIA channel properties and response functions.

This class provides an interface to the AIA channels and methods for calculating the effective area and wavelength response functions as a function of wavelength.

Parameters:
  • channel (Quantity) – Wavelength of AIA channel.

  • instrument_file (str, optional) – Path to AIA instrument file. If not specified, the latest version will be downloaded from SolarSoft.

Examples

>>> import astropy.units as u
>>> from aiapy.response import Channel
>>> c = Channel(171 * u.angstrom)  
>>> c.telescope_number  
3
>>> c.name  
'171'
>>> c.channel  
<Quantity 171. Angstrom>

Attributes Summary

channel

Nominal wavelength at which the bandpass of the channel is centered.

contamination

crosstalk

Contamination of effective area from crosstalk between channels.

effective_area

Uncorrected effective area as a function of wavelength.

entrance_filter_efficiency

focal_plane_filter_efficiency

gain

Gain of the CCD camera system.

geometrical_collecting_area

is_fuv

Returns True for UV and visible channels 1600, 1700, 4500 Å.

name

plate_scale

primary_reflectance

quantum_efficiency

secondary_reflectance

telescope_number

Label denoting the telescope to which the given channel is assigned.

wavelength

Array of wavelengths over which channel properties are calculated.

Methods Summary

eve_correction(obstime, correction_table)

Correct effective area to give good agreement with full-disk EVE data.

wavelength_response(*[, obstime, ...])

The wavelength response function is the product of the gain and the effective area.

Attributes Documentation

channel#

Nominal wavelength at which the bandpass of the channel is centered.

contamination#
crosstalk#

Contamination of effective area from crosstalk between channels.

On telescopes 1, 3, and 4, both channels are always illuminated. This can lead to contamination in a channel from the channel with which it shares a telescope. This impacts the 94 and 304 Å channels as well as 131 and 335 Å. See Section 2.2.1 of [1] for more details.

References

effective_area#

Uncorrected effective area as a function of wavelength.

According to Section 2 of [boerner], the effective area is given by,

\[A_{eff}(\lambda) = A_{geo}R_P(\lambda)R_S(\lambda)T_E(\lambda)T_F(\lambda)D(\lambda)Q(\lambda),\]

where,

  • \(A_{geo}\): geometrical collecting area

  • \(R_P\), \(R_S\): reflectances of primary and secondary mirrors, respectively

  • \(T_E\), \(T_F\): transmission efficiency of the entrance and focal-plane filters, respectively

  • \(D\): contaminant transmittance of optics

  • \(Q\): quantum efficiency of the CCD

The effective area contains information about the efficiency of the telescope optics and its sensitivity as a function of wavelength. All of the telescope properties are read from the AIA instrument files available in SolarSoft.

References

[boerner]

Boerner et al., 2012, Sol. Phys., 275, 41

entrance_filter_efficiency#
focal_plane_filter_efficiency#
gain#

Gain of the CCD camera system.

According to Section 2 of [boerner1], the gain of the CCD-camera system, in DN per photon, is given by,

\[G(\lambda) = \frac{hc}{\lambda}\frac{g}{a}\]

where \(g\) is the camera gain in DN per electron and \(\approx 3.65\) eV per electron is a conversion factor.

References

[boerner1]

Boerner et al., 2012, Sol. Phys., 275, 41

geometrical_collecting_area#
is_fuv#

Returns True for UV and visible channels 1600, 1700, 4500 Å.

name#
plate_scale#
primary_reflectance#
quantum_efficiency#
secondary_reflectance#
telescope_number#

Label denoting the telescope to which the given channel is assigned.

See crosstalk for context of why this is important.

wavelength#

Array of wavelengths over which channel properties are calculated.

Methods Documentation

eve_correction(obstime, correction_table)[source]#

Correct effective area to give good agreement with full-disk EVE data.

The EVE correction factor is given by,

\[\frac{A_{eff}(\lambda_n,t_0)}{A_{eff}(\lambda_E,t_e)}\]

where \(A_{eff}(\lambda_n,t_0)\) is the effective area at the nominal wavelength of the channel (\(\lambda_n\)) at the first calibration epoch and \(A_{eff}(\lambda_E,t_e)\) is the effective area at the `obstime` calibration epoch interpolated to the effective wavelength (\(\lambda_E\)).

Note

This function is adapted directly from the aia_bp_corrections.pro routine in SolarSoft.

Parameters:
Return type:

Quantity

wavelength_response(*, obstime=None, include_eve_correction=False, include_crosstalk=True, correction_table)[source]#

The wavelength response function is the product of the gain and the effective area.

The wavelength response as a function of time and wavelength is given by,

\[R(\lambda,t) = (A_{eff}(\lambda) + A_{cross}(\lambda))G(\lambda)C_T(t)C_E(t)\]

where,

  • \(A_{eff}(\lambda)\) is the effective area as a function of wavelength

  • \(A_{cross}(\lambda)\) is the effective area of the crosstalk channel

  • \(G(\lambda)\) is the gain of the telescope

  • \(C_T(t)\) is the time-dependent correction factor for the instrument degradation

  • \(C_E(t)\) is the time-dependent EVE correction factor

Parameters:
  • obstime (Time, optional) – If specified, a time-dependent correction is applied to account for degradation.

  • include_eve_correction (bool, optional) – If true and obstime is not None, include correction to EVE calibration. The time-dependent correction is also included.

  • include_crosstalk (bool, optional) – If true, include the effect of crosstalk between channels that share a telescope

  • correction_table (Table) – Table of correction parameters. See aiapy.calibrate.util.get_correction_table for more information.

Return type:

Quantity