Omicron  4.2.0
An algorithm to detect and characterize transient events in gravitational-wave detectors
Omicron

Table of Contents

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 The original matlab code has been replaced by an optimized C++ architecture to offer a fast processing of the data.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-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:

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:

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

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