gwdetchar-omega task

Documentation adapted from the GWDetchar documentation pages for gwdetchar-omega.

The gwdetchar.omega module provides a python implementation of the Omega gravitational-wave burst detection pipeline, used extensively for characterisation of transient noise in LIGO. This pipeline is designed around the Q-transform and is used to analyze hundreds of channels.

Requirements

This task requires the following packages that may not be included in the requirements list for dqrtasks:

• gwpy

• gwdetchar

Description

The gwdetchar.omega command-line interface is a Q-transform utility for generating omega scans. The simplest usage is as follows:

python -m gwdetchar.omega -i <interferometer> <gps-time>

For example,

python -m gwdetchar.omega -i L1 1126259461.5

Because this task was not originally designed for use wiht the DQR, this script must be paired with an additional task that creates the required data.json file once the gwdetchar-omega task is complete.

Example command-line

This is the help message:

$ gwdetchar-omega --help
usage: gwdetchar-omega [-h] [-V] [-i IFO] [-o OUTPUT_DIRECTORY]
                       [-f CONFIG_FILE] [-d] [-D] [-s] [-t FAR_THRESHOLD]
                       [-y FREQUENCY_SCALING] [-c COLORMAP] [-j NPROC]
                       gpstime

Produce an Omega scan for a list of channels around a given GPS time

This utility can be used to process an arbitrary list of detector channels
with minimal effort in finding data. The input should be an INI-formatted
configuration file that lists processing options and channels in contextual
blocks. For more information, see gwdetchar.omega.config.

positional arguments:
  gpstime               GPS time or datestring to scan

optional arguments:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  -i IFO, --ifo IFO     IFO prefix for this analysis, default: None
  -o OUTPUT_DIRECTORY, --output-directory OUTPUT_DIRECTORY
                        output directory for the Omega scan, default:
                        ~/public_html/wdq/{IFO}_{gpstime}
  -f CONFIG_FILE, --config-file CONFIG_FILE
                        path to configuration file to use, can be given
                        multiple times (files read in order), default: choose
                        a standard one based on IFO and GPS time
  -d, --disable-correlation
                        disable cross-correlation of aux channels, default:
                        False
  -D, --disable-checkpoint
                        disable checkpointing from previous runs, default:
                        False
  -s, --ignore-state-flags
                        ignore state flag definitions in the configuration,
                        default: False
  -t FAR_THRESHOLD, --far-threshold FAR_THRESHOLD
                        white noise false alarm rate threshold (Hz) for
                        processing channels, default: 3.171e-08
  -y FREQUENCY_SCALING, --frequency-scaling FREQUENCY_SCALING
                        scaling of all frequency axes, default: log
  -c COLORMAP, --colormap COLORMAP
                        name of colormap to use, default: viridis
  -j NPROC, --nproc NPROC
                        the number of processes to use when reading data,
                        default: 8

Example config

[omegascan]
description = stationarity test
librarian = derek.davis@ligo.org
include_in_dag = True
tier = 1
question = Are known sources of noise without auxiliary witnesses active?
executable = gwdetchar-omega
request_memory = 400MB
arguments = "${t_0} -i V1 -f V1-O3-llhoft-omegascan.ini -o ${outdir} -c viridis"

Note that an additional configurations file must be listed containing the channel information. The syntax for this configuration file is the same as on the command line.

Example results page

An example page for GW170817 can be found here.