Source-linked AI summary
The LIGO Open Science Center
Michele Vallisneri, Jonah Kanner, Roy Williams, Alan Weinstein, Branson Stephens
TL;DR
The paper addresses how LIGO data can be released in a form usable by researchers outside the collaboration, students, and the public. It presents the LOSC’s archive, portal services, documentation, and tutorials, centered on the August 2014 release of Initial LIGO’s S5 dataset. The release provides a testbed for broader participation, education, and future data releases.
Problem
LIGO needed to make its publicly funded data comprehensible and usable beyond the LIGO Scientific Collaboration.
Method
The LOSC combines validated strain, data-quality, and injection products with web services, metadata, documentation, tutorials, and example code.
Results
In August 2014, the LOSC released Initial LIGO’s S5 dataset, its first large dataset from a design-sensitivity run.
Takeaways & Limitations
The S5 release serves as a testbed for broader participation, education, and discussion of useful LIGO data representations.
Abstract
from arXiv · showhide
The LIGO Open Science Center (LOSC) fulfills LIGO's commitment to release, archive, and serve LIGO data in a broadly accessible way to the scientific community and to the public, and to provide the information and tools necessary to understand and use the data. In August 2014, the LOSC published the full dataset from Initial LIGO's "S5" run at design sensitivity, the first such large-scale release and a valuable testbed to explore the use of LIGO data by non-LIGO researchers and by the public, and to help teach gravitational-wave data analysis to students across the world. In addition to serving the S5 data, the LOSC web portal (losc.ligo.org) now offers documentation, data-location and data-quality queries, tutorials and example code, and more. We review the mission and plans of the LOSC, focusing on the S5 data release.
1. Introduction
LIGO pursued open data to broaden access beyond the LIGO Scientific Collaboration and support discovery, reproducibility, collaboration, and education. Its roadmap distinguishes an early discovery phase from a later observational phase with delayed public releases.
- 1. Introduction: The planned audience extends beyond LSC researchers to amateur scientists, students, and the broader public.
- 1. Introduction: LIGO data openness was motivated by public ownership and by expected gains in discovery, reproducibility, collaboration, and education.The paper also connects open access with identifying problems more rapidly, multimessenger astronomy, and broader participation.
- 1. Introduction: During the early discovery phase, full data access remains restricted to the LSC while Advanced LIGO measurements and detections are still developing.Early candidate-event alerts are nevertheless broadcast to participating astronomers seeking electromagnetic counterparts.
- 1. Introduction: The observational phase begins after plentiful detections, a 3 × 10^7 Mpc3 yr surveyed volume, or 3.5 years after formal acceptance.The entire dataset is then released in six-month segments with 24-month latency to allow instrumental and environmental corrections.
2. The LIGO Open Science Center
The LOSC extends LIGO’s archival infrastructure to communities without the LSC’s tacit knowledge by combining validated data, metadata, web services, and learning materials. Its flagship achievement was the August 2014 public release of Initial LIGO’s S5 dataset.
- 2. The LIGO Open Science Center: The LOSC adapts LIGO data preservation and access for non-LSC scientists and the general public, whose needs differ from those of trained LSC members.
- 2. The LIGO Open Science Center: The team’s milestones covered S5 strain release, validation and annotation, a web portal, data-quality services, and tutorials with example code.
- 2. The LIGO Open Science Center: In August 2014, LOSC released Initial LIGO’s S5 dataset, containing 537, 546, and 457 science-data days from H1, H2, and L1.S5 ran from November 2005 through October 2007 and was Initial LIGO’s first design-sensitivity run.
- 2. The LIGO Open Science Center: The S5 dataset is intended as a testbed for useful data representations, a teaching resource, and a foundation for subsequent releases.The LOSC team planned continued support while preparing the S6 release.
3. The LOSC data archive
The LOSC archive reduces thousands of detector channels to three accessible time series: calibrated strain, data quality, and hardware-injection markers. These products are packaged with metadata, documentation, and tools that support search construction, interpretation, and reuse.
- 3. The LOSC data archive: The archive provides 4,096-Hz calibrated strain plus 1-Hz data-quality and hardware-injection time series.Initial LIGO generated approximately 6,600 channels, so these products simplify access for scientific and pedagogical use.
- 3. The LOSC data archive: LOSC files are packaged in HDF5 and frame formats, include interpretive metadata, and are published for browser and scripted download.
- 3. The LOSC data archive: The calibrated strain h(t) records gravitational-wave signals together with instrumental strain-equivalent noise; S5 data were essentially all noise because no events were found.
- 3. The LOSC data archive: Approximately 30% of the S5 data-taking period consists of gaps, represented by NaNs and identified by the one-second DATA marker.
- 3.2. Data quality: Data-quality bitmasks encode CATn veto status at 1 Hz, enabling users to construct search-specific segment lists.Different categories support different uses, including event candidates with CAT2 and upper-limit derivation with CAT3.
- 3.3. Injections: A separate 1-Hz bitmask identifies hardware-injection seconds and types, allowing users either to exclude injections or test algorithms on them.The portal also lists the times and parameters of all S5 hardware injections.
4. LOSC data services
The LOSC portal supplements downloadable files with catalogs, timeline visualizations, event-time detector queries, tutorials, and example code. These services expose data availability, quality, and context across LIGO and partner observatories.
- 4. LOSC data services: The portal catalog exposes file metadata and strain statistics, and supports queries for data between arbitrary GPS times.Results can be displayed as tables color-coded by data quality and injection presence.
- 4.2. Timeline: The Timeline tool visualizes data-quality and injection duty cycles from individual seconds to multiyear intervals using cached averages.
- 4.2. Timeline: The Timeline currently covers five detectors in three countries over 12 years, including GEO600 and Virgo alongside the three LIGO detectors.
- 4. LOSC data services: MySources identifies which LIGO, GEO, or Virgo detectors were collecting science data at user-specified event times and locations.
- 4. LOSC data services: Tutorials and example code in Python, MATLAB, and C teach users to download, parse, and manipulate LOSC files.They are intended as transparent starting points rather than a comprehensive replacement for LIGO Algorithm Library.
5. Summary
The LOSC makes LIGO data broadly usable by providing public data access alongside documentation, tutorials, and open software. The S5 release establishes a foundation for participation, education, future releases, and understanding gravitational-wave sources.
- The LOSC provides public LIGO data products with documentation, tutorials, and free open software for users inside and outside the collaboration.The service is designed to make the data comprehensible and usable by scientists, students, and others.
- The Initial LIGO S5 release supports participation by professional and amateur scientists and students, while also serving outreach and education.The associated web services and tutorials are used both by outside researchers and by new LSC students.
- Future LOSC releases will include data from the higher-sensitivity Advanced LIGO detectors, supporting studies of curved spacetime and gravitational-wave sources.The stated scientific uses include understanding source dynamics, origins, and properties.