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data_reduction [2013/09/05 22:25]
mjc [Flux Calibration] 		data_reduction [2025/07/03 00:31] (current)
onken Update for v2
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 ==== PyWiFeS Data Reduction ==== ==== PyWiFeS Data Reduction ====
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 +**The processes in version 2 of PyWiFeS largely build upon the excellent work of the previous PyWiFeS developers. Thus, we retain the original documentation here, but note that several aspects have undergone significant revision in the current version, described in Onken et al. (in prep). Documentation for the new processes may also be found in [[https://pywifes-pipeline.readthedocs.io/en/latest/index.html| our ReadTheDocs site]] or in the README and CHANGELOG files in [[https://github.com/PyWiFeS/pywifes| the GitHub repository]] **
  
 This page details the algorithms and techniques employed in PyWiFeS data reduction procedures.  For details on how to actually run the reduction script, see the [[documentation| main documentation]] page. For the ordered list of reduction steps in the default reduction script, see the [[default_reduction| default reduction steps]] page. This page details the algorithms and techniques employed in PyWiFeS data reduction procedures.  For details on how to actually run the reduction script, see the [[documentation| main documentation]] page. For the ordered list of reduction steps in the default reduction script, see the [[default_reduction| default reduction steps]] page.
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 ==== Flux Calibration ==== ==== Flux Calibration ====
-links to stdstar catalogs...+After WiFeS data have undergone standard image processing steps (e.g., bias subtraction, cosmic ray rejection, flat-fielding), the absolute flux scale of the data must still be assessed.  This is done by observing spectrophotometric standard stars and comparing their observed fluxes to reference spectra.  In PyWiFeS this is done with the procedure outlined schematically in the Figure below, using routines defined in the 'wifes_calib' sub-module.
  
 {{ :wiki:flux_cal_wifes.png?600 |}} {{ :wiki:flux_cal_wifes.png?600 |}}
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 +The flux calibration step corrects for the smooth instrument throughput curve, as well as atmospheric extinction.  However sharp absorption features caused by molecules in the atmosphere (primarily O<sub>2</sub> and H<sub>2</sub>O) remain, and must be corrected in object spectra (bottom panel below) by measuring their structure in the spectra of flux-calibrated smooth spectrum stars (top panel below).
  
 {{ :wiki:telluric_wifes.png?400 |}} {{ :wiki:telluric_wifes.png?400 |}}
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