CALWEBB_TSO3

The algorithms for CALWEBB_TSO3, the 3rd stage of the JWST calibration pipeline for all Time Series Observations (TSO) data, are described.  These algorithms process the data from calibrated slope images to extracted photometry and spectroscopy for each integration.

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The CALWEBB_TSO3 module is the 3rd stage in the calibration pipeline for the all Time Series Observation (TSO) data. The inputs to this stage are the calibrated slope images (CALWEBB_IMAGE2 and CALWEBB_SPEC2 output) and the outputs are extracted photometry and spectroscopy as appropriate.The steps are listed in Figure 1 with the flow from the top to the bottom.

Unless otherwise stated, the algorithms described are the baseline version.

Figure 1. CALWEBB_TSO3

The steps in the CALWEBB_TSO3 module are shown. The common steps are shown in cyan with the Imaging and Spectroscopy specific steps shown in yellow and purple respectively.


Common steps

Outlier detection

A 2nd pass at outlier detection is done using the image stack. The majority of the outliers will be due to cosmic rays undetected during the 1st pass at outlier detection done in CALDETECTOR1. An iterative sigma clipping algorithm is used in pixel coordinates on the image stack. The presence of an outlier results in a pixel flag being set.

Create exposure level products

The exposure level products are re-created at this stage to provide the highest quality products that include the results of the ensemble processing (a 2nd pass outlier detection). These products are for the archive and include the unrectified 2D images and rectified 2D images.



Imaging steps

Extract photometry

Aperture photometry with a predefined aperture is performed for each integration providing the time series photometry. 



Spectroscopy steps

Extract spectroscopy

The extraction is done using a boxcar for each integration providing time series spectroscopy.

White-light photometry

The 1D extracted spectra are collapsed to create time series white-light photometry for the spectral observations.




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