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Version: 1.10.1.dev3+g52d10edd

PypeIt is a Python package for semi-automated reduction of astronomical, spectroscopic data. Its algorithms build on decades-long development of previous data reduction pipelines by the developers. The reduction procedure - including a complete list of the input parameters and available functionality - is provided by this online documentation.

PypeIt is a set of commands designed to perform the reduction without any additional coding.

This release of PypeIt is designed to be used by both advanced spectroscopists with prior data reduction expertise and astronomers with no prior experience of data reduction. It is highly configurable and designed to be applied to any standard slit-imaging spectrograph, and can accommodate long-slit, multi-slit, as well as cross-dispersed echelle spectra.


If you use PypeIt in your research, please cite the following publications (PypeIt BibTeX Entries are provided below):

  • Prochaska et al. (2020, JOSS): arXiv, JOSS

  • Prochaska et al. (2020, Zenodo): Zenodo

If there is no place to include the relevant citations in the text of the publication, please include the following acknowledgement (provided in latex and using the provided PypeIt BibTeX Entries):

This research made use of \ttfamily{PypeIt},\footnote{\url{}}
a Python package for semi-automated reduction of astronomical slit-based spectroscopy
\citep{pypeit:joss_pub, pypeit:zenodo}.


PypeIt receives direct funding from the following sources:

  • NASA (ADAP-A20-0412)

  • W.M. Keck Observatory

  • University of California Observatories

We also rely on important in-kind contributions from individuals at Caltech, the Multiple Mirror Observatory, and elsewhere.

What this version provides

What this version is missing (i.e. what we are working on)

  • Full 2D coadd support

  • Additional QA outputs

  • A dashboard to monitor/control PypeIt

  • Keck/HIRES, Keck/ESI support


If you are mainly here to use PypeIt to reduce your observational data then this section is for you. Ideally, you will need to go not much further than the few links in this section take you.

If you have problems, we have a very active “PypeIt Users” Slack workspace. We periodically update the invitation here. If you find a bug or have a feature request, please submit an issue.

Standard outputs


PypeIt is an open-source, community developed package. Astronomers are encouraged to join the project and should review our Code of Conduct and PypeIt Development Procedures and Guidelines. We would also appreciate if you contact the lead developers (JXP, JFH) before beginning development activities.

The following persons have contributed substantially to the development of PypeIt.

  • J Xavier Prochaska

  • Joseph F. Hennawi

  • Kyle B. Westfall

  • Ryan J. Cooke

  • Feige Wang

  • Tiffany Hsyu

  • Frederick B. Davies

  • Emanuele Paolo Farina

  • Debora Pelliccia

  • James Reichwein

PypeIt BibTeX Entries

       author = {{Prochaska}, J. Xavier and {Hennawi}, Joseph F. and {Westfall}, Kyle B. and
         {Cooke}, Ryan J. and {Wang}, Feige and {Hsyu}, Tiffany and
         {Davies}, Frederick B. and {Farina}, Emanuele Paolo},
        title = "{PypeIt: The Python Spectroscopic Data Reduction Pipeline}",
      journal = {arXiv e-prints},
     keywords = {Astrophysics - Instrumentation and Methods for Astrophysics},
         year = 2020,
        month = may,
          eid = {arXiv:2005.06505},
        pages = {arXiv:2005.06505},
archivePrefix = {arXiv},
       eprint = {2005.06505},
 primaryClass = {astro-ph.IM},
       adsurl = {},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}

    doi = {10.21105/joss.02308},
    url = {},
    year = {2020},
    publisher = {The Open Journal},
    volume = {5},
    number = {56},
    pages = {2308},
    author = {J. Xavier Prochaska and Joseph F. Hennawi and Kyle B. Westfall and Ryan J. Cooke and Feige Wang and Tiffany Hsyu and Frederick B. Davies and Emanuele Paolo Farina and Debora Pelliccia},
    title = {PypeIt: The Python Spectroscopic Data Reduction Pipeline},
    journal = {Journal of Open Source Software}

       author = {{Prochaska}, J. Xavier and {Hennawi}, Joseph and {Cooke}, Ryan and
         {Westfall}, Kyle and {Wang}, Feige and {EmAstro} and {Tiffanyhsyu} and
         {Wasserman}, Asher and {Villaume}, Alexa and {Marijana777} and
         {Schindler}, JT and {Young}, David and {Simha}, Sunil and
         {Wilde}, Matt and {Tejos}, Nicolas and {Isbell}, Jacob and
         {Fl{\"o}rs}, Andreas and {Sandford}, Nathan and {Vasovi{\'c}}, Zlatan and
         {Betts}, Edward and {Holden}, Brad},
        title = "{pypeit/PypeIt: Release 1.0.0}",
         year = 2020,
        month = apr,
          eid = {10.5281/zenodo.3743493},
          doi = {10.5281/zenodo.3743493},
      version = {v1.0.0},
    publisher = {Zenodo},
       adsurl = {},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}