modules.extract_spectrum
Functions for extracting the echelle spectra.
Created by DMK on 10/22/2023
Last updated by DMK on 11/6/2023
Module Contents
Functions
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Function to pull a postage stamp image of a single order block from a full frame echellogram. |
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Function to extract a 1D spectrum from a single order's 2D spectrum image using simple sum extraction. |
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Function to extract a 1D spectrum from a single order's 2D spectrum using optimal extraction. |
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Main function to run to extract 1D spectra from the processed 2D image of the echellogram. It writes out the extracted spectrum as a FITS file. |
- modules.extract_spectrum.get_order_image_block(full_image, order_trace, order_width)
Function to pull a postage stamp image of a single order block from a full frame echellogram.
- Parameters:
full_image (array) – The full frame flux image.
order_trace (array) – The order trace to define the center of the order block. The array is 1D with size (number of dispersion pixels).
order_width (int) – The cross dispersion pixel width of an order.
- Returns:
output_image_block – The postage stamp image of an order around its trace. The array has shape (number of dispersion pixels, order_width).
- Return type:
array
- modules.extract_spectrum.sum_extraction(flux_image, err_image, num_pixels, order_width, background_option)
Function to extract a 1D spectrum from a single order’s 2D spectrum image using simple sum extraction.
- Parameters:
flux_image (array) – The 2D spectrum (image block) of a single order to extract.
err_image (array) – The 2D error spectrum (image block) of a single order to extract.
num_pixels (int) – The number of dispersion pixels in an order.
order_width (int) – The cross dispersion pixel width of an order.
background_option (str) – A config entry that sets what to do with background subtraction. Must be either ‘subtract’ or ‘none’.
- Returns:
flux_sum_extract (array) – The 1D extracted flux spectrum for the input order.
err_sum_extract (array) – The 1D extracted flux error spectrum for the input order.
- modules.extract_spectrum.optimal_extraction(flux_image, err_image, num_pixels, order_width, background_option)
Function to extract a 1D spectrum from a single order’s 2D spectrum using optimal extraction.
- Parameters:
flux_image (array) – The 2D spectrum (image block) of a single order to extract.
err_image (array) – The 2D error spectrum (image block) of a single order to extract.
num_pixels (int) – The number of dispersion pixels in an order.
order_width (int) – The cross dispersion pixel width of an order.
background_option (str) – A config entry that sets what to do with background subtraction. Must be either ‘fixed’ (background value is fixed based on the edges of the order image) or ‘fit’ (where it is a free parameter in the pixel slice fitting).
- Returns:
flux_opt_extract (array) – The 1D extracted flux spectrum for the input order.
err_opt_extract (array) – The 1D extracted flux error spectrum for the input order.
- modules.extract_spectrum.extract_spectrum(file_indices, trace, header_df, extraction_method, background_option, config)
Main function to run to extract 1D spectra from the processed 2D image of the echellogram. It writes out the extracted spectrum as a FITS file.
- Parameters:
file_indices (array) – List of indices (in the header information file) for frames to extract.
trace (array) – The order trace as created with “trace_echelle” and read in from the “trace.fits” file.
header_df (pandas DataFrame) – The compiled information from the file headers.
extraction_method (str) – The extraction method to use, taken from the main config file. Currently must be either ‘optimal_extraction’ or ‘sum_extraction’.
background_option (str) – A config entry that sets what to do with background subtraction. For optimal extraction must be either ‘fixed’ or ‘fit’. For sum extraction must be either ‘subtract’ or ‘none’.
config (dict) – The overall config file defined using YAML with all parameters for running the reduction and analysis pipeline.
- Return type:
None.