Omicron is a software analysis tool designed to perform the Q-transform of a time series. This type of time-frequency decomposition offers a multi-resolution spectrogram of the input signal. This spectrogram can be visualized in user-friendly web reports. Moreover, a signal-to-noise ratio threshold can be applied to the spectrogram pixels to produce "triggers".

Omicron has been derived from a well-known 'burst-type' search pipeline called Q-pipeline (a.k.a Omega). The original matlab code has been replaced by an optimized C++ architecture to offer a fast processing of the data. As a result, Omicron is able to process many data streams in parallel.

Omicron high-resolution spectrogram of GW170817.

User programs

The Omicron package comes with a collection of user programs using Omicron libraries:

omicron.cc: this is the main program to perform a Q-transform analysis of your data.
omicron-x.cc: this is the main program to search gravitational waves with omicron-x.
omicron-x-event.cc: this program generates an html page to characterize an Ox event.
omicron-print.cc: this program reads omicron trigger files and prints distributions of trigger parameters.
omicron-plot.cc: this program reads omicron trigger files and plots distributions of trigger parameters.
omicron-coinc.cc: this program compares two omicron trigger sets.
omicron-listfile.cc: this program discovers the list of Omicron trigger files.
omicron-scanfile.cc: this program scans a list of trigger files and detect corrupted files.
omicron-metric-print.cc: this program measures the so-called "omicron metric" for a given structure in the time-frequency plane.

Develop a project on top of Omicron libraries

Omicron offers a set of C++ classes to run and visualize Q-transform analyses. The corresponding libraries can be used to develop user programs or projects:

C++ classes: documentation for Omicron C++ classes.

Install Omicron (conda)

Install Omicron from the conda-forge channel:

conda create -c conda-forge --name omicron omicron

Simply activate your omicron environment to use Omicron libraries and programs:

conda activate omicron

Build Omicron from sources

First, define your source and installation directories. For example:

export OMICRON_SRCDIR=${HOME}/src
export OMICRON_INSTALLDIR=${HOME}/opt/Omicron
mkdir -p ${OMICRON_SRCDIR} ${OMICRON_INSTALLDIR}

You can download the Omicron source tarball from gitlab:

 cd ${OMICRON_SRCDIR}
 wget https://git.ligo.org/virgo/virgoapp/Omicron/-/archive/[X.Y.Z]/Omicron-[X.Y.Z].tar.gz
 tar -xzf Omicron-[X.Y.Z].tar.gz

where [X.Y.Z] is the Omicron version of your choice.

Alternatively, you can get a development copy of the Omicron software using git and select a release tag:

 cd ${OMICRON_SRCDIR}
 git clone https://git.ligo.org/virgo/virgoapp/Omicron.git
 cd Omicron/
 git checkout [X.Y.Z]

The Omicron package relies on several external packages which you must install on your machine:

GWOLLUM libraries offer many analysis tools needed by Omicron.
CMake is used to build Omicron.
Doxygen is used to build the Omicron documentation. This package is optional.

Here, we give step-by-step instructions to build Omicron for UNIX (bash/sh) systems.

# go to the source directory
cd ${OMICRON_SRCDIR}/Omicron/

# create the build directory
mkdir ./build/; cd ./build/

# configure Omicron
cmake -DCMAKE_INSTALL_PREFIX=${OMICRON_INSTALLDIR} ${OMICRON_SRCDIR}/Omicron

# compile Omicron
make

# install Omicron
make install

An environment script has been generated. It must be sourced before using Omicron:

source ${OMICRON_INSTALLDIR}/etc/omicron.env.sh

You can test that Omicron is correctly installed by typing:

omicron version

If you have the Doxygen software installed in your machine, you can access Omicron documentation with a web browser at file://${OMICRON_INSTALLDIR}/share/doc/Omicron/html/index.html.

Documentation and links

General

Omicron published paper (arXiv)
Omicron technical note
Omicron gitlab page: this is the code repository.
Omicron wiki: additional and specific documentation is provided there.
Omicron issue tracker: use this link to report bugs, request new features...
Laboratoire de Physique des 2 infinis Irène Joliot-Curie (IJCLab)

Related pages

See all documentation pages in the Related Pages

Authors

Florent Robinet - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab) Orsay, France - contact

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