Folders and files

Name		Name	Last commit message	Last commit date
Latest commit History 5,758 Commits
.github		.github
docs		docs
extern		extern
helpers		helpers
notebooks		notebooks
recipes/conda		recipes/conda
scripts		scripts
sherpa-test-data @ 1b026cb		sherpa-test-data @ 1b026cb
sherpa		sherpa
.coveragerc		.coveragerc
.gitattributes		.gitattributes
.gitignore		.gitignore
.gitmodules		.gitmodules
CITATION		CITATION
CONTRIBUTING.md		CONTRIBUTING.md
COPYRIGHT		COPYRIGHT
LICENSE		LICENSE
MANIFEST.in		MANIFEST.in
README.md		README.md
RELEASE_NOTES		RELEASE_NOTES
conda_build_config.yaml		conda_build_config.yaml
pyproject.toml		pyproject.toml
pytest.ini		pytest.ini
readthedocs.yml		readthedocs.yml
setup.cfg		setup.cfg
setup.py		setup.py
test_requirements.txt		test_requirements.txt
versioneer.py		versioneer.py

Repository files navigation

Table of Contents

Sherpa

Sherpa is a modeling and fitting application for Python. It contains apowerful language for combining simple models into complex expressionsthat can be fit to the data using a variety of statistics andoptimization methods. It is easily extensible to include user models,statistics, and optimization methods. It provides a high-level UserInterface for interactive data-analysis work, such as within aJupyter notebook, and it can also be used as a library component,providing fitting and modeling capabilities to an application.

What can you do with Sherpa?

fit 1D (multiple) data including: spectra, surface brightness profiles, light curves, general ASCII arrays
fit 2D images/surfaces in Poisson/Gaussian regime
build complex model expressions
import and use your own models
use appropriate statistics for modeling Poisson or Gaussian data
import new statistics, with priors if required by analysis
visualize the parameter space with simulations or using 1D/2D cuts of the parameter space
calculate confidence levels on the best fit model parameters
choose a robust optimization method for the fit: Levenberg-Marquardt, Nelder-Mead Simplex or Monte Carlo/Differential Evolution.

Documentation for Sherpa is available atRead The Docsand also forSherpa in CIAO.

AQuick Start Tutorialis included in thenotebooks folder and can be opened with anipython notebook.

Acknowledging or Citing Sherpa

If you use Sherpa for work/research presented in a publication please cite the Sherpa papers:

Sherpa Paper 2024 (ADS BibTex)

Sherpa Paper 2007 (ADS BibTex )

Sherpa Paper 2001 (ADS BibTex)

If you are using AASTeX and plan to submit an article to one of the AAS journals, we recommend adding a \software{...} tag to your manuscript that cites Sherpa (see theAASTeX guide for more information), e.g.:

\software{Sherpa \citep{2001SPIE.4477...76F,2007ASPC..376..543D,2024arXiv240910400S}}

License

This program is free software: you can redistribute it and/or modify it underthe terms of the GNU General Public License as published by the Free SoftwareFoundation, either version 3 of the License, or (at your option) any laterversion. A copy of the GNU General Public License can be found in theLICENSE file provided with the source code, or from theFree Software Foundation.

How To Install Sherpa

Full installation instructionsare part of theRead The Docsdocumentation, and should be read if the following is not sufficient.

It is strongly recommended that some form ofvirtual environment isused with Sherpa.

Sherpa is tested against Python versions 3.10 and 3.11 with experimental support for Python 3.12.

The last version of Sherpa which supported Python 2.7 isSherpa 4.11.1.

Using Conda

Sherpa is provided for both Linux and macOS operating systems runningPython 3.10, 3.11, and (experimental) 3.12. It can be installed with thecondapackage manager by saying

$ conda install -c https://cxc.cfa.harvard.edu/conda/sherpa -c conda-forge sherpa

Using pip

Sherpa is also availableon PyPI and so can be installedwith the following command (which requires that the NumPy package isalready installed).

% pip install sherpa

Building from source

Source installation is available for platforms incompatible with thebinary builds, or for when the default build options are not sufficient(such as including support for theXSPEC model library).The steps are described in thebuilding from sourcedocumentation.

History

Sherpa is developed by theChandra X-rayObservatory to provide fitting and modellingcapabilities to theCIAO analysis package. Ithas been released ontoGitHub for users toextend (whether to other areas of Astronomy or in other domains).