Stingray: Next-Generation Spectral Timing

Stingray logo, outline of a stingray on top of a graph of the power spectrum of an X-ray binary

Stingray is a Python library designed to perform times series analysis and related tasks on astronomical light curves. It supports a range of commonly-used Fourier analysis techniques, as well as extensions for analyzing pulsar data, simulating data sets, and statistical modelling. Stingray is designed to be easy to extend, and easy to incorporate into data analysis workflows and pipelines.


If you use Stingray for work presented in a publication or talk, please help the project by providing a proper citation.


Current Capabilities

1. Data handling and simulation

  • loading event lists from fits files (and generally good handling of OGIP-compliant missions, like RXTE/PCA, NuSTAR/FPM, XMM-Newton/EPIC, NICER/XTI)

  • constructing light curves and time series from event data

  • various operations on time series (e.g. addition, subtraction, joining, and truncation)

  • simulating a light curve with a given power spectrum

  • simulating a light curve from another light curve and a 1-d (time) or 2-d (time-energy) impulse response

  • simulating an event list from a given light curve _and_ with a given energy spectrum

  • Good Time Interval operations

  • Filling gaps in light curves with statistically sound fake data

1. Fourier methods

  • power spectra and cross spectra in Leahy, rms normalization, absolute rms and no normalization

  • averaged power spectra and cross spectra

  • dynamical power spectra and cross spectra

  • maximum likelihood fitting of periodograms/parametric models

  • (averaged) cross spectra

  • coherence, time lags

  • Variability-Energy spectra, like covariance spectra and lags needs testing

  • covariance spectra; needs testing

  • bispectra; needs testing

  • (Bayesian) quasi-periodic oscillation searches

  • Lomb-Scargle periodograms and cross spectra

  • Power Colors

3. Other time series methods

  • pulsar searches with Epoch Folding, \(Z^2_n\) test

  • Gaussian Processes for QPO studies

  • cross correlation functions

Future Plans

We welcome feature requests: if you need a particular tool that’s currently not available or have a new method you think might be usefully implemented in Stingray, please get in touch!

Other future additions we are currently implementing are:

  • bicoherence

  • phase-resolved spectroscopy of quasi-periodic oscillations

  • Fourier-frequency-resolved spectroscopy

  • full HEASARC-compatible mission support

  • pulsar searches with \(H\)-test

  • binary pulsar searches

Platform-specific issues

Windows uses an internal 32-bit representation for int. This might create numerical errors when using large integer numbers (e.g. when calculating the sum of a light curve, if the lc.counts array is an integer). On Windows, we automatically convert the counts array to float. The small numerical errors should be a relatively small issue compare to the above.

Installation instructions

There are currently three ways to install Stingray:

  • via conda

  • via pip

  • from source

Below, you can find instructions for each of these methods.


A minimal installation of Stingray requires the following dependencies:

  • astropy>=4.0

  • numpy>=1.17.0

  • scipy>=1.1.0

  • matplotlib>=3.0,!=3.4.0

In typical uses, requiring input/output, caching of results, and faster processing, we recommend the following dependencies:

  • numba (highly recommended)

  • tbb (needed by numba)

  • tqdm (for progress bars, always useful)

  • pyfftw (for the fastest FFT in the West)

  • h5py (for input/output)

  • pyyaml (for input/output)

  • emcee (for MCMC analysis, e.g. for PSD fitting)

  • corner (for the plotting of MCMC results)

  • statsmodels (for some statistical analysis)

For pulsar searches and timing, we recommend installing

  • pint-pulsar

Some of the dependencies are available in conda, the others via pip. To install all required and recommended dependencies in a recent installation, you should be good running the following command:

$ pip install astropy scipy matplotlib numpy h5py tqdm numba pint-pulsar emcee corner statsmodels pyfftw tbb

For the Gaussian Process modeling in stingray.modeling.gpmodeling, you’ll need the following extra packages

  • jax

  • jaxns

  • tensorflow

  • tensorflow-probability

  • tinygp

  • etils

  • typing_extensions

Most of these are installed via pip, but if you have an Nvidia GPU available, you’ll want to take special care following the installation instructions for jax and tensorflow(-probability) in order to enable GPU support and take advantage of those speed-ups.

For development work, you will need the following extra libraries:

  • pytest

  • pytest-astropy

  • tox

  • jinja2==3.1.3

  • docutils

  • sphinx-astropy

  • nbsphinx>=0.8.3,!=0.8.8

  • pandoc

  • ipython

  • jupyter

  • notebook

  • towncrier<22.12.0

  • black

Which can be installed with the following command:

$ pip install pytest pytest-astropy jinja2<=3.0.0 docutils sphinx-astropy nbsphinx pandoc ipython jupyter notebook towncrier<22.12.0 tox black


Installing via conda

If you manage your Python installation and packages via Anaconda or miniconda, you can install stingray via the conda-forge build:

$ conda install -c conda-forge stingray

That should be all you need to do! Just remember to run the tests before you use it!

Installing via pip

pip-installing Stingray is easy! Just do:

$ pip install stingray

And you should be done! Just remember to run the tests before you use it!

Installing from source (bleeding edge version)

For those of you wanting to install the bleeding-edge development version from source (it will have bugs; you’ve been warned!), first clone our repository on GitHub:

$ git clone --recursive

Now cd into the newly created stingray directory. Finally, install stingray itself:

$ pip install -e "."

Installing development environment (for new contributors)

For those of you wanting to contribute to the project, install the bleeding-edge development version from source. First fork our repository on GitHub and clone the forked repository using:

$ git clone --recursive<your github username>/stingray.git

Now, navigate to this folder and run the following command to add an upstream remote that’s linked to Stingray’s main repository. (This will be necessary when submitting PRs later.):

$ cd stingray
$ git remote add upstream

Now, install the necessary dependencies:

$ pip install astropy scipy matplotlib numpy pytest pytest-astropy h5py tqdm

Finally, install stingray itself:

$ pip install -e "."

Test Suite

Please be sure to run the test suite before you use the package, and please report anything you think might be bugs on our GitHub Issues page.

Stingray uses py.test and tox for testing. To run the tests, try:

$ tox -e test

You may need to install tox first:

$ pip install tox

To run a specific test file (e.g.,, try:

$ cd stingray
$ py.test tests/

If you have installed Stingray via pip or conda, the source directory might not be easily accessible. Once installed, you can also run the tests using:

$ python -c 'import stingray; stingray.test()'

or from within a python interpreter:

>>> import stingray
>>> stingray.test()

Building the Documentation

The documentation including tutorials is hosted here. The documentation uses sphinx to build and requires the extensions sphinx-astropy and nbsphinx.

One quick way to build the documentation is using our tox environment:

$ tox -e build_docs

You can build the API reference yourself by going into the docs folder within the stingray root directory and running the Makefile:

$ cd stingray/docs
$ make html

If that doesn’t work on your system, you can invoke sphinx-build itself from the stingray source directory:

$ cd stingray
$ sphinx-build docs docs/_build

The documentation should be located in stingray/docs/_build. Try opening ./docs/_build/index.rst from the stingray source directory.

Using Stingray

A Spectral timing exploration

In this Tutorial, we will show an example spectral timing exploration of a black hole binary using NICER data. The tutorial includes a hardness-intensity diagram, the modeling of the power density spectrum, power colors, lag-frequency, lag-energy, and rms/covariance spectra.

Stingray fundamentals


Additional information

Indices and tables