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 GUAR`ANTEE 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
Obit is a Unix software environment with a limited set of developed
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
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
Obit Mac Installation using Homebrew
There is an installation package for Obit on Apple MacIntosh computers
developed by Ludwig Schwardt (firstname.lastname@example.org) at SARAO that,
when it works, is very straightforward. There may be conflicts with other
The instructions are:
Using homebrew to install Obit on Macs
# If you do not have Homebrew (http://mxcl.github.com/homebrew/),
# uncomment and run the following and follow the instructions
# ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
# 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 no further development activities will be done.
These are available via Subversion but are very out of date.
% svn checkout https://svn.cv.nrao.edu/svn/ObitInstall/StableReleases/Obit-20JAN09
% svn checkout https://svn.cv.nrao.edu/svn/ObitInstall/StableReleases/Obit-01JAN10
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
InstallObit.sh 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
% 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 https://github.com/bill-cotton/Obit/
This will checkout the installation package described below.
This software can be installed as described in the
Updates are then possible using:
% svn update
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
ObitTalk User documentation.
ObitTalk Software (python) architecture documentation.
Obit Software (c) architecture documentation.
Obit single dish (c) software architecture documentation.
doxygen generated Obit C language documentation.
doxygen generated Obit Single dish C language documentation.
Obit Algorithmic Development Memos
pdf Image Pixelization and Dynamic Range (EVLA memo 114).
pdf Automatic CLEAN Windowing (EVLA memo 116) .
pdf Beam Squint and Stokes V on the VLA (EVLA memo 113).
pdf Ionospheric Effects and Imaging and Calibration of the VLA (EVLA memo 118).
pdf Ionospheric Effects and Calibration of the VLA at 327 MHz (EVLA memo 117).
pdf Tools for Ionospheric Studies (EVLA memo 115).
pdf Users guide to Obit software for Mustang (GBT 3 mm bolometer
Obit Development Memo Series
- no. 1:
pdf Testing of multithreading implementation in Obit.
- no. 2:
pdf Testing of parallel processing of spectral line imaging.
- no. 3:
pdf Partial solution to wideband interferometric imaging problem.
- no. 4:
pdf Imaging Data From the MUSTANG Bolometer Array.
- no. 5:
pdf Multithreaded Image Interpolation.
- no. 6:
pdf Parallel Facet Imaging in Obit.
- no. 7:
pdf Simulating UV Data in Obit.
- no. 8:
pdf Testing Obit with a 100 GByte simulated dataset.
- no. 9:
pdf Performance Enhancement of the autoWindow technique.
- no. 10:
pdf User's Guide to Obit Software for the GBT/Mustang 3 mm
- no. 11:
pdf Tests on a High Frequency EVLA 100 GByte Simulated Dataset.
- no. 12:
pdf Tests on a High Frequency EVLA TeraByte Simulated Dataset
- no. 13:
pdf Effects of Baseline Dependent Time Averaging of UV Data.
- no. 14:
pdf A vector Fast Sine/Cosine Routine.
- no. 15:
pdf Multi-facet CLEANing in Obit.
- no. 16:
pdf Removal of Interference from Low Frequency VLA data.
pdf Measurements of, and corrections for, the EVLA beam pattern.
pdf Attempt to adapt Sault-Wieringa 1994 wideband deconvolution to high dynamic
pdf High dynamic range wideband imaging.
pdf Wideband phase and delay calibration.
pdf Efficacy of Obit Threading on an EVLA Dataset.
pdf Accurate Calibration of VLBI Measurements of Circular Polarization.
pdf Hanning smoothing and removal of strong, quasi-stationary,
narrow band RFI
pdf Multi-resolution CLEANing in Obit.
pdf False Detection Rate of Source Finding.
pdf Amplitude calibration of ALMA using polarized calibrators.
pdf A Fast Vector Exp Function.
pdf A New Method for Cross Polarized Delay Calibration of Radio Interferometers.
pdf EVLA Continuum Scripts: Outline of Data Reduction and Heuristics.
pdf [Draft] On-axis Instrumental Polarization Calibration for Circular Feeds.
pdf [Draft] On the Stability of EVLA C Band Polarization.
pdf On-axis Instrumental Polarization Calibration for Linear Feeds.
pdf Calibrating ALMA Phases with WVR Data.
pdf Polarization calibration and imaging of EVLA Demo Hercules A.
pdf Comparison of GPU and Multithreading for Interferometric DFT Model Calculation
pdf Comparison of GPU, Single- and Multi-threading for Interferometric Gridding
- no. 37:
pdf A Fast Sine/Cosine Routine: Revenge of the Vector Processors.
- no. 38:
pdf Wideband Widefield calibration models.
- no. 39:
pdf Differential Instrumental Polarization Calibration.
- no. 40:
pdf ALMA Continuum Scripts: Outline of Data Reduction and Heuristics.
- no. 41:
pdf Image Combination by Feathering.
- no. 42:
pdf Tiling the Field of View with Facets.
pdf False Detection Rate of Source Finding Revisited.
- no. 44:
pdf Simplified EVLA OTF Interferometry.
- no. 45:
pdf Note on Selfcalibration of EVLA Snapshot Imaging.
- no. 46:
pdf Note on Polarization Calibration of the EVLA.
- no. 47:
pdf EVLA Beam Holography take 2
- no. 48:
pdf Feathering vs. UV Data Combination.
- no. 49:
pdf AVX2: First Look.
- no. 50:
pdf Inner UV Taper Weighting for Synthesis Imaging.
- no. 51:
pdf ngVLA Dynamic Range.
- no. 53:
pdf Note on tuning the Middle autoWindow Loop: adding Deferents to Epicycles.
- no. 54:
pdf Manual Peeling in Obit.
- no. 55:
pdf Deep High Dynamic Range Imaging: A Case Study at S Band.
- no. 56:
pdf Confusion limited surveys with the ngVLA spiral configuration.
- no. 57:
pdf Efficacy of Double Buffered I/O.
- no. 58:
pdf Swimming Against the Current: DFT Imaging Revisited.
- no. 59
pdf The Ionosphere at L Band: MeerKAT.
- no. 60
pdf Source Finding in Crowded Fields.
- no. 61
pdf Notes on icc and AVX.
- no. 62
pdf MeerKAT L Band Polarimetric Calibration.
- no. 63
pdf Wide-band, Wide-field Imager MFImage.
- no. 64
pdf Distributed Processing in c in Obit.
Presentations related to Obit
pdf W. Cotton, Presentation giving high level description of Obit
and a discussion of the autoWindow feature.
J. Uson, Application of the Squint beam squint correction to
VLA HI observations of super thin galaxies.
J. Uson, Steps towards a VLA or ALMA pipeline.
There are several components of Obit and related software.
This and required third party software can be obtained as described above.
This is the basic Obit package supporting astronomical images and
radio interferometry data and applications.
Ths is a single dish "On-the-fly" (OTF) imaging addon to Obit.
Only FITS format files are supported.
ObitSD requires Obit.
This is a Unix/X-Windows program that serves as an Image display
Communications is through the xmlrpc protocol.
It is currently usable by Obit and ObitSD to display images and
interactively select CLEAN windows.
ObitView can browse and display FITS images or local AIPS images can
be displayed if requested via the xmlrpc interface.
ObitView requires Obit.
ParselTongue is a python-based scripting and interactive command line
interface to astronomical data processing packages.
ParselTongue can execute AIPS or Obit tasks (compiled programs) and use the
Obit python interface in a script.
ParselTongue is an EU funded component of RadioNet and is being
developed by the Joint Institute for VLBI in Europe (JIVE).
Information on ParselTongue is available
ObitTalk is derived from ParselTongue but with more interactive
User documentation is available
as well as in extensive on-line documentation.
The (USA) National Radio Astronomy Observatory
is operated by Associated Universities, Inc. and is a Facility of
the (USA) National Science Foundation.
Comments? Questions? Problems?