Obit - Astronomy Software for Algorithm Development
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Obit is a group of software packages for handling radio astronomy data, especially interferometric and single dish OTF 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 or OTF data, 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.

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 SKA/SA 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

Obit Stable Releases

There is a system of stable releases of Obit for which bugs will be fixed but no further development activities will be done. These are available via Subversion but are very out of date.

This will create a directory with the release name (e.g. Obit-01JAN10) in the current working directory which is the root of the Obit installation. Once a copy is obtained fron Subversion, it can be installed using the shell script. See the README file for details. The third party software to be installed will be downloaded as part of the installation so internet access is required. Updates for bug fixes can be obtained by cding to the root directory and:
% svn update

Using Subversion to obtain Development Obit

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:
% svn checkout

This will checkout the installation package described below. This software can be installed as described in the README file.
Updates are then possible using:
% svn update

The Subversion server has a Web based browser that displays the current state of the repository.


Software Documentation

Obit Algorithmic Development Memos

Obit Development Memo Series

  • no. 45: pdf Note on Selfcalibration of EVLA Snapshot Imaging.
  • no. 46: pdf Note on Polarization Calibration of the EVLA.

    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?