1.106. mkRef

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

HIFI/Pipeline/Level 1 Pipeline

Description

A task to extract emission in reference positions.

For DBS Modes this task calculates the difference in emission between the two chop positions. The resulting spectra give(s) a rough idea of whether or not the user chopped onto a region with emission.

To make the description easier, we use the following definitions: At level 0 and 0.5, we have the following spectra:

  • ON_src : ON spectra - source position: telescope pointing to the source, chop phase from source position

  • ON_ref : ON spectra - reference position: telescope pointing to the source, chop phase from reference position (ref1)

  • OFF_src : OFF spectra - source position: telescope pointing to reference position (ref2), chop phase from source position

  • OFF_ref : ON spectra - source position: telescope pointing to the reference position (ref2), chop phase from reference position (ref2)

Note that the ON_src and OFF_src point to the same source in sky.

During the level 1 pipeline, the reference and off subtraction are carried through. The reference subtraction leads to the two 'NOD' spectra:

  • NOD_ON = ON_src - ON_ref

  • NOD_OFF = OFF_src - OFF_ref

The off subtraction, finally, averages NOD_ON and NOD_OFF, i.e. ON = (NOD_ON + NOD_OFF) / 2. These spectra will be included as science ON (isLine=True) spectra in the level 1 timeline products. The science OFF spectra, on the other hand (isLine=False), will contain the NOD_OFF spectra.

Now, a simple calculation shows that

REF = 2*(NOD_OFF-ON) = (ON_ref-OFF_ref) + (OFF_src-ON_src).

Assuming that OFF_src and ON_src are (within noise) the same, we should see noise in the REF if the two reference positions do not show emission.

The task is designed to work only after applying doRefSubtract and doOffSubtract .

Example

Example 1: Simple example.
refHtp = mkRef(htp=htp)

API details

Properties

HifiTimelineProduct htp [INPUT, MANDATORY, default=No default value]

The HTP to process.

HifiProduct cal [OUTPUT, OPTIONAL, default=No default value]

The output reference spectra - with one dataset per LO group / raster point.

Boolean doAvg [INPUT, OPTIONAL, default=True]

Specify whether to average the spectra in ON and the spectra in NOD_OFF.

Boolean doResample [INPUT, OPTIONAL, default=No default value]

Specify whether to resample the spectra in ON and the spectra in NOD_OFF per group on a common frequency scale. The scale is picked from the first ON spectrum. If the doAvg option is set to True resampling is always performed. By default, if the doAvg option is set to False, no resampling is done.

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]

Flag to indicate whether the execution of the module should be ignored.

See also

History

  • 2011-01-01 - CB: Converted to a task and distributed to ICC.
  • 2011-01-01 - CB: Changed to work with level 1 instead of level 0.5
  • 2012-08-06 - Melchior: First java implementation