StepOpacity

class sofia_redux.instruments.hawc.steps.stepopacity.StepOpacity

Bases: StepParent

Apply an atmospheric opacity correction.

This step corrects for atmospheric transmission based on a standard model of the atmosphere, the altitude/ZA in the header, and the instrument response by band. The correction factor is multiplied into the flux images, and propagated to the variance and covariance images.

Opacity correction factors are calculated and applied by algorithms in the sofia_redux.calibration package:

• sofia_redux.calibration.pipecal_config: pipecal_config

• sofia_redux.calibration.pipecal_util: get_tellcor_factor, apply_tellcor

Input for this image must contain either STOKES and ERROR images, as produced by the sofia_redux.instruments.hawc.steps.StepStokes pipeline step, or else PRIMARY IMAGE and NOISE images, as produced by the sofia_redux.instruments.hawc.steps.StepScanMap pipeline step. For polarimetry data, covariance images (COVAR Q I, COVAR U I, and COVAR Q U) are also expected. The output DataFits has the same extensions as the input.

Methods Summary

run()	Run the data reduction algorithm.
setup()	Set parameters and metadata for the pipeline step.

Methods Documentation

run()

Run the data reduction algorithm.

Because this step is single-in, single-out (SISO), self.datain must be a DataFits object. The output is also a DataFits object, stored in self.dataout.

The process is:

1. Retrieve an opacity correction factor from the sofia_redux.calibration package.

2. Multiply flux and error images by the correction factor. Multiply covariance images by the correction factor squared.

setup()

Set parameters and metadata for the pipeline step.

Output files have PRODTYPE = ‘calibrate’, and are named with the step abbreviation ‘CAL’.

No parameters are currently defined for this step.