1.64. doSidebandGain

Full Name: herschel.hifi.pipeline.generic.DoSidebandGainTask
Alias: doSidebandGain
Type: Java Task - Java Task
Import: from herschel.hifi.pipeline.generic import DoSidebandGainTask
Category

HIFI/Pipeline/Level 2 Pipeline

Description

Apply the sideband gain coefficients to the flux values.

Using the 'sidebands' parameter you can specify to what sideband the data should be transformed to. The output products can be retrieved from the task as parameters 'htp' and/or 'image'. Note that the original timeline product 'htp' is modfied under this operation. The sideband gain coefficients are retrieved from the helper object of type {@link CalSidebandCoeff} that typically is composed by the {@link MkSidebandGainTask}-task. Note that this helper object does not explicitly on band or date information. Hence this information should (typically) be passed to the provider of the helper object (i.e. {@link MkSidebandGainTask}-task which accepts the {@link HifiTimelineProduct} as input). In case no such helper class is provided the default coefficients 0.5 are applied.

It changes the label for the intensity axis to "Antenna Temperature" or "Main Beam Temperature" - depending on whether the Antenna Temperature correction (default) or Main Temperature correction has been, respectively.

The gains applied to the data are written to the metadata of the level 2 spectra and are denoted by usbGain and lsbGain for the upper and lower sidebands, respectively. Intensity scales HIFI is a double sideband (DSB) instrument. In consequence, application of sideband gains mean that the detected lines are calibrated to single sideband (SSB) scale, while the continuum contains contribution from both sidebands and remains at the DSB scale. If the gains are unity then the continuum is at twice the SSB scale. Beware, however, that the introduction of sideband gain coefficients at the low frequency end of band 2a mean that is not the case there.

Example

Example 1: In HIPE
doSidebandGain = DoSidebandGain()
htpUpper = doSidebandGain(htp=spec, cal=gains)
htpLower = doSidebandGain.image
doSidebandGain(htp=spec, cal=gains, sideband='upper')
htpUpper = doSidebandGain.htpUpper

API details

Properties

HifiTimelineProduct htp [INOUT, MANDATORY, default=no default value]

The input timeline product to be processed. In case both sidebands should be returned, we here return the upper sideband.

HifiTimelineProduct image [OUTPUT, OPTIONAL, default=no default value]

The timeline product with flux values corrected as lower sideband values (in case both sidebands have been selected).

String sideband [INPUT, OPTIONAL, default='both']

Specify the sideband the spectra should be transformed to. Possible values are 'both', 'lower', 'upper'. Default value is 'both'.

CalSidebandCoeff cal [INPUT, OPTIONAL, default=no default value]

Object that allows to obiatn gains coefficients to be applied to the flux values. The information on sideband, LO frequency and the IF frequency grid is provided so that IF frequency dependent gain coefficients can be obtained.

PipelineConfiguration params [INPUT, OPTIONAL, default=no default value]

Pipeline configuration parameters that can be passed to the task.

Boolean ignore [INPUT, OPTIONAL, default=no default value]

If set to True task is not executed.

See also

History

  • 2009-04-01 - Melchior: Initial implementation.
  • 2009-06-24 - Melchior: Remove change in frequency scale.
  • 2009-08-28 - Melchior: New way of passing / retrieving the sideband gains coefficients.
  • 2011-08-14 - Melchior: Renamed to DoSidebandGainTask