Obit - Astronomy Software for Algorithm Development
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Obit is a group of software packages for handling radio astronomy data, especially interferometric imaging. This software is made available under the GNU General Public License in the hope that it might be useful but "as is" with NO GUARANTEE OR ASSURANCE of suitability, usability or correctness for any purpose. Obit is developed and maintained by Bill Cotton at The National Radio Astronomy Observatory in Charlottesville, Virginia, USA. Obit is intended primarily as an environment in which new data processing algorithms can be developed and tested but which can also be used for production processing of a certain range of scientific problems.

Obit is a Unix software environment with a limited set of developed applications. It is an object--oriented set of class and utility libraries allowing access to multiple disk--resident data formats. In particular, access to either AIPS disk data or FITS files. A number of low level applications are implemented such as imaging and deconvolving interferometer. High-level applications may be either compiled c programs or python scripts; most of the high-level operations have bindings to python. Obit applications are interoperable with Classic AIPS and the ObitTalk python interface gives access to AIPS tasks as well as Obit libraries and tasks.

A preprint of a paper describing the Obit package (PASP, 2008, 120, 439) is available.

NOTE: Python 3 upgrade

As of version 608 (Nov. 2019), the Obit python routines should work with either python version 2.7 or python 3, whichever is run using command "python" (or /usr/bin/python). Part of this upgrade is to require some python 3 features (e.g. parentheses in print statements) in existing scripts, even using python 2.7. This was a major revision of the python interface and it no longer works with older versions of python.

Binary Distribution of Obit

Periodic binary distributions of Obit are available here.

Obit Mac Installation using Homebrew

There is an installation package for Obit on Apple MacIntosh computers developed by Ludwig Schwardt ( at SARAO that, when it works, is very straightforward. There may be conflicts with other installation packages.
The instructions are:

Using homebrew to install Obit on Macs

# If you do not have Homebrew (,
# uncomment and run the following and follow the instructions
# ruby -e "$(curl -fsSL"
# Homebrew changes occasionally so you may need to check the site in future.
# This also needs git and curl.
# After that do:

% brew tap ska-sa/tap
% brew install --HEAD obit

Obtaining Development Obit

Github no longer supports the subversion server and now only git. The anonymous server allows you to get the most up-to-date version of software and then do updates to the software.

To checkout the Obit installation package from Subversion, including most third party software:
%git clone

This will checkout the installation package described below. This software can be installed as described in the README file.
Updates are then possible from the top level Obit directory using:
% git pull origin master
This should (hopefully) not require a passphrase.

Note: If you have a working linux installation build using the old NRAO svn server, a description of a relatively painless migration to the new server is available in a migration file.


Software Documentation

Obit Algorithmic Development Memos

Obit Development Memo Series

Presentations related to Obit

Obit Components

There are several components of Obit and related software. This and required third party software can be obtained as described above.
The (USA) National Radio Astronomy Observatory (NRAO) is operated by Associated Universities, Inc. and is a Facility of the (USA) National Science Foundation.

Comments? Questions? Problems?