abscal.wfc3.reduce_grism_coadd

Extract and co-add a group of WFC3 grism spectra.

This submodule

  • Takes an input exposure table (from preprocess_table_create)

  • Groups the exposures by grating

  • Finds and extracts the standard star spectrum from each exposure

  • Groups the extracted spectra by program and visit

  • Co-adds together each group

While it can produce substantial output, both in logging and plots, it can also run without user intervention. User intervention is only asked for in choosing the best centroid fit for the zeroth order image.

Authors

  • Brian York (all python code)

  • Ralph Bohlin (original IDL code)

Use

This module can be run from the command line (although one of the abscal.commands or abscal.idl_commands scripts would be preferred for that), but is mostly intended to be imported, either by binary scripts or for use from within python:

from abscal.wfc3.reduce_grism_coadd import coadd

output_table = coadd(input_table, command_line_arg_namespace, override_dict)

The override dict allows for many of the default input parameters to be overriden (as defaults – individual per-exposure overrides defined in the data files will still take priority). Parameters that can be overriden in coadd are:

width: default 22

The width (in pixels) of the cross-correlation search region

wbeg: default 7500 (G102), 10000 (G141)

The lowest valid wavelength

wend: default 11800 (G102), 17500 (G141)

The highest valid wavelength

regbeg_m1: default -13500 (G102), -19000 (G141)

The start of the -1st spectral order region

regend_m1: default -3800 (G102), -5100 (G141)

The end of the -1st spectral order region

regbeg_p1: default -3800 (G102), -5100 (G141)

The start of the 1st spectral order region

regend_p1: default 13500 (G102), 19000 (G141)

The end of the 1st spectral order region

regbeg_p2: default 13500 (G102), 19000 (G141)

The start of the 2nd spectral order region

regend_p2: default 27000 (G102), 38000 (G141)

The end of the 2nd spectral order region

Module Contents

Functions

coadd(input_table, **kwargs)

Co-adds grism data

additional_args(**kwargs)

Additional command-line arguments.

parse_args(**kwargs)

Parse command-line arguments.

main(**kwargs)

Run the coadd function.
abscal.wfc3.reduce_grism_coadd.coadd(input_table, **kwargs)

Co-adds grism data

Takes the input table, and

  • filters out the grism exposures, then for each

    • looks for an extracted spectrum

    • if none is found, call reduce_grism_extract to make one

  • groups the grism exposures by program/visit/grism, then for each group

    • co-adds the spectra in that group

    • creates a FITS file (and an ASCII table) for each co-added spectrum

  • writes out a new version of the input table with updated values (if any)

Parameters:
Returns:

input_table – The updated table of exposures

Return type:

abscal.common.exposure_data_table.AbscalDataTable

abscal.wfc3.reduce_grism_coadd.additional_args(**kwargs)

Additional command-line arguments.

Provides additional command-line arguments that are unique to the co-add process.

Returns:

additional_args – Dictionary of tuples in the form (fixed,keyword) that can be passed to an argument parser to create a new command-line option

Return type:

dict

abscal.wfc3.reduce_grism_coadd.parse_args(**kwargs)

Parse command-line arguments.

Gets the custom arguments from co-add and extract, and passes them to the joint command-line option function.

Returns:

res – parsed argument namespace

Return type:

namespace

abscal.wfc3.reduce_grism_coadd.main(**kwargs)

Run the coadd function.

Runs the co-add function if called from the command line, with command-line arguments added in.

Parameters:

kwargs (dict) – Dictionary of parameters to override when running.