Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time



PRESTO is a large suite of pulsar search and analysis software developed primarily by Scott Ransom mostly from scratch, and released under the GPL (v2). It was primarily designed to efficiently search for binary millisecond pulsars from long observations of globular clusters (although it has since been used in several surveys with short integrations and to process a lot of X-ray data as well). It is written primarily in ANSI C, with many of the recent routines in Python. According to Steve Eikenberry, PRESTO stands for: PulsaR Exploration and Search TOolkit!

PRESTO has discovered over 1000 pulsars, including approximately 400 recycled and/or binary pulsars!

New in Version 4.0:

  • This is a major release since it involves big changes to the Python portions of the codebase:
    • Python v3.7 or newer is now required.
    • A long-standing memory issue was fixed with Anaconda Python (running python tests/ will tell you if you have that issue or not).
    • Swig v4 is used to generate the Python wrappers of the PRESTO C library.
    • Big thanks to Shami Chatterjee and Bradley Meyers who helped me get to the bottom of this!
  • There is a FAQ with lots of information!
  • PRESTO has a dockerfile that allows it to build on Docker Hub automatically. Thanks to Nick Swainston for this! (more testing and improvements would be welcome)
  • makes it much easier to manually zap interference from simple searches (no need for copying ".inf" files and running both and zapbirds).
  • realfft and zapbirds can now be called on many files at once on the command line. This benefits HPC systems which often don't like many programs running serially on many small files.
  • A new python interface to the internal prepfold folding code (simplefold), as well as wrappers of fast C implementations of $\chi^2$ and $Z^2_N$ (thanks to Matteo Bachetti).
  • Many bug fixes and minor improvements, including one that would cause segfaults with very large dispersion sweeps in prepdata and prepsubband, and a problem with prepfold significance calculations.

In Version 3.0.1:

  • This is a minor release which fixes several issues and adds some minor improvements:
    • Fix of long-standing rfifind bug that could cause the program to hang if channels had zero variance
    • Multiple Python3-related bug fixes
    • Added -debug flag to prepfold to allow debugging of TEMPO calls to make polycos
    • can now read observation parameters from filterbank or PSRFITS input files. And you can write a dedisp_*.py dedispersion script, based on the plan, using the -w option
    • The rednoise program now writes a corresponding *_red.inf file
    • Update of the Tutorial document, including a new slide on red noise

In Version 3.0:

  • This major release of PRESTO includes a massive restructuring of python code and capabilities. Things should work with Python versions 2.7 and Python 3.6 and 3.7 at least. The installation of the python code has changed and has become more "pythonic" so that PYTHONPATH is not needed, and all of the various modules are now under a top-level "presto" module. For example, to use the psr_utils module you would now do:

    import presto.psr_utils as pu

    rather than

    import psr_utils as pu

    All of these changes will likely lead to code breakage and bugs!

    Please check your code and processing carefully and post issues (and hopefully pull requests) if you find them.

    The installation instructions have been updated in the INSTALL file.

    Huge thanks thanks go to Gijs Molenaar, Matteo Bachetti, and Paul Ray for the work that they have done helping with this!

  • There is also a new examplescripts directory where you will find some example code to do a lot of important things, like

    • Fully dedispersing an observation:
    • Fully searching a dedispersed observation:
    • Sifting the results of a full search:
    • Searching short chunks of a long time series:
    • Making a really nice P-Pdot plane:
    • and a few others.

Status of Version 2.2:

  • Version 2.2 was the last version of PRESTO to work with the old-style python interface which requires Python v2.7 or earlier and is "installed" in-place and used via having $PRESTO/lib/python in your PYTHONPATH. There will probably be occasional bug fixes for v2.2 in the v2.2maint branch of PRESTO. You can get it using:

    git checkout -b v2.2maint origin/v2.2maint

    and then installing as per the INSTALL file.

Improvements in Version 2.1:

  • accelsearch now has a "jerk" search capability (thanks to (then) UVA undergrad Bridget Andersen for help with this!). This makes searches take a lot longer, but definitely improves sensitivity when the observation duration is 5-15% of the duration of the orbital period. Typically -wmax should be set to 3-5x -zmax (and you probably never need to set -zmax to anything larger than 300).
  • Ability to ignore bad channels on the command line (-ignorechan) (see and


PRESTO is written with portability, ease-of-use, and memory efficiency in mind, it can currently handle raw data from the following pulsar machines or formats:

  • PSRFITS search-format data (as from GUPPI at the GBT, PUPPI and the Mock Spectrometers at Arecibo, and much new and archived data from Parkes)
  • 1-, 2-, 4-, 8-, and 32-bit (float) filterbank format from SIGPROC
  • A time series composed of single precision (i.e. 4-byte) floating point data (with a text ".inf" file describing it)
  • Photon arrival times (or events) in ASCII or double-precision binary formats

Notice that the following formats which used to be supported are not:

  • Wideband Arecibo Pulsar Processor (WAPP) at Arecibo
  • The Parkes and Jodrell Bank 1-bit filterbank formats
  • SPIGOT at the GBT
  • Berkeley-Caltech Pulsar Machine (BCPM) at the GBT

If you need to process them, you can either checkout the "classic" branch of PRESTO (see below), which is not being actively developed. Or you can use DSPSR to convert those formats into SIGPROC filterbank or (even better) PSRFITS search format. You can grab DSPSR here. If you really need to get one of these machines working in modern PRESTO, let me know and we can probably make it happen.

The software is composed of numerous routines designed to handle three main areas of pulsar analysis:

  1. Data Preparation: Interference detection (rfifind) and removal (zapbirds) , de-dispersion (prepdata, prepsubband, and mpiprepsubband), barycentering (via TEMPO).
  2. Searching: Fourier-domain acceleration (accelsearch), single-pulse (, and phase-modulation or sideband searches (search_bin).
  3. Folding: Candidate optimization (prepfold) and Time-of-Arrival (TOA) generation (
  4. Misc: Data exploration (readfile, exploredat, explorefft), de-dispersion planning (, date conversion (mjd2cal, cal2mjd), tons of python pulsar/astro libraries, average pulse creation, flux density estimation, and more...
  5. Post Single Pulse Searching Tools: Grouping algorithm (, Production and of single pulse diagnostic plots (,, and

Many additional utilities are provided for various tasks that are often required when working with pulsar data such as time conversions, Fourier transforms, time series and FFT exploration, byte-swapping, etc.

References: The Fourier-Domain acceleration search technique that PRESTO uses in the routine accelsearch is described in Ransom, Eikenberry, and Middleditch (2002), the "jerk" search capability is described in Andersen & Ransom (2018), and the phase-modulation search technique used by search_bin is described in Ransom, Cordes, and Eikenberry (2003). Some other basic information about PRESTO can be found in my thesis.

Support/Docs: I may eventually get around to finishing the documentation for PRESTO (or not), but until then you should know that each routine returns its basic usage when you call it with no arguments. I am also willing to provide limited support via email (see below). And make sure to check out the!

Tutorial: There is a tutorial in the "docs" directory which walks you through all the main steps of finding pulsars using PRESTO.

Getting it:

The PRESTO source code is released under the GPL and can be browsed or gotten from here in many different ways (including zipped or tar'd or via git). If you are too lazy to read how to get it but have git on your system do:

git clone git://

To update it on a regular basis do

git pull

and then re-make things in $PRESTO/src.

For more detailed installation instructions, see

If you don't want to mess with git (which means that you will need to re-install a tarball whenever there are updates) you can get it from the "Download Source" link on the github page.

If you want the "classic" branch, do the following:

git clone git://
cd presto
git checkout -b classic origin/classic

then build as per the (old) INSTALL file.


If you plan to tweak the code, I highly suggest that you use git and clone the directory (or fork it using an account on github). And if you want to contribute your changes back, please give me a "pull request"!

Code contributions and/or patches to fix bugs are most welcome!

Final Thoughts:

Please let me know if you decide to use PRESTO for any "real" searches, especially if you find pulsars with it!

And if you find anything with it, it would be great if you would cite either my thesis or whichever of the three papers listed above is appropriate.

Also note that many people are now citing software using the ASCL. PRESTO is there as well.



Big thanks go to Steve Eikenberry for his help developing the algorithms, Dunc Lorimer and David Kaplan for help with (retired) code to process BCPM, SCAMP, and Spigot data, among other things, Jason Hessels and Patrick Lazarus for many contributions to the Python routines, and (alphabetical): Bridget Andersen, Anne Archibald, Cees Bassa, Matteo Bachetti, Slavko Bogdanov, Fernando Camilo, Shami Chatterjee, Kathryn Crowter, Paul Demorest, Paulo Freire, Nate Garver-Daniels, Chen Karako, Mike Keith, Maggie Livingstone, Ryan Lynch, Erik Madsen, Bradley Meyers, Gijs Molenaar, Timothy Olszanski, Chitrang Patel, Paul Ray, Alessandro Ridolfi, Paul Scholz, Maciej Serylak, Ingrid Stairs, Kevin Stovall, Nick Swainston, and Joeri van Leeuwen for many comments, suggestions and patches!

Scott Ransom