Gravitational Wave Open Science Center

Event Portal Usage Notes

Overview

The Event Portal provides an interface for finding strain data for events discovered with LIGO and Virgo.

Catalogs

Catalogs are collections of events. You can see a listing of available catalogs on the Catalog List page.

Version numbers

Some events may be listed in the database with multiple version numbers. Different versions of the same astrophysical event may differ in one or more of the following:
  • Different versions of calibration applied to the associated strain data
  • Different cleaning techniques applied to the associated strain data
  • Different analysis results
  • Different publications
You can see all versions for a given event by entering the event's name in the Name Query Form. For example, try searching for GW150914.

Information for individual events

Individual event views (e.g. GW150914 v3) provide information about a given event entry. This includes:

  • Documentation: Documentation or reference to give context for a given event.
  • GPS: End time or merger time of the event in GPS seconds.
  • GraceDB: If available, a link to the corresponding entry in GraceDB, a database of preliminary results from low-latency searches.
  • GCN: Links to associated GCN notices and circulars, used to communicate low-latency results at the time of discovery.
  • Timeline: Link to segment and data quality information
  • Notes: Technical notes. In many cases, this gives details about which version of strain is included in this version.

Strain Data

Available strain data for the event are displayed on cards, with one card for each detector with data available. Detectors do not run at all times, so any given event may not have data from all detectors. Each card includes:
  • The detector code (H1 for Hanford, L1 for Livingston, V1 for Virgo, G1 for GEO)
  • A time-frequency plot showing the Q-transform of a small segment of data, centered on the merger time. These are proudced using the Q-transform method in gwpy. You can make similar plots using the Quickview notebook.
  • Data download links for strain data available in different durations (typically 32 seconds and 4096 seconds), different sampling frequencies (16384 Hz or 4096 Hz) and different file formats (GW frame files, HDF5, or ASCII text).

Technical details

A number of notes about GWOSC event releases and their use may be seen on the event release technical details page.

Image credit

Image on event portal home page is adopted from art by Aurore Simonnet at Sonoma State.