GWTC-1 Documentation

A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs, 2015-2017.

Description

This catalog is described in: GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs.

The table of marginal triggers includes triggers from O1 and O2 that passed the initial threshold of a FAR less than one per thirty days in at least one of the two matched-filter searches, but were not assigned a probability of astrophysical origin of more than 50% by either pipeline.

Strain Data

Confident Detections Marginal Triggers

Parameter Values

Parameter values are sourced from Tables I, II, III, and IV in the GWTC-1 paper. The false alarm rates, SNR, and pastro values shown in the Event List view correspond to the search pipeline with the lowest false alarm rate. Values from additional pipelines are available by clicking the name of each event.

Updated Parameter Estimation Results

Updated parameter estimation results associated with the reanalysis of confident detections for all events in GWTC-1-confident/ except GW170817 (see documentation for details) appear under each event within the gray box with heading "GWTC-1 PE for GWyymmdd (GWTC-2.1)", where the "(GWTC-2.1)" distinguishes the results from the original GWTC-1-confident PE results that used the same strain data found on these event pages. These new values are the result of updated analysis methods only.

Associated Data Products

Special Cases

GW170817

L1 data near GW170817 contains a loud glitch. This glitch is included in the data released with GWTC-1. Special frames with the glitch removed may be found in DCC document T1700406 or in the previous GW170817-v2 event release. Note that these two versions of the glitch removed frames correspond to different publications, and so have differences in both the calibration version and the glitch model used.

GW170608

The H1 detector was nominally outside of observing mode at the time of this event. This data release includes H1 data around the time of this event, by using a modified segment list, as was done for the published analysis. For additional H1 data near the time of this event, see the GW170608 background data set.

Notes on Strain Data

Data files containing calibrated strain are available for 4096 seconds centered on each event. Note that LIGO and Virgo data contain a number of instrumental artifacts, many of which are noted on the strain data notes page.

Data are calibrated strain time series sampled 16384 Hz as well as a copy down-sampled to 4096 Hz. The down-sampled data were obtained using the scipy 'decimate' method. The anti-aliasing filter introduces errors up to a few percent in magnitude and a few milli-radians across the band, with larger errors close to the Nyquist frequency.

Advanced LIGO and Virgo strain data are not calibrated below 10 Hz, as noted on the strain data notes page. 


from scipy.signal import decimate
data4seg = decimate(data16seg, 4, zero_phase=True)

Reading Files

Channel names found inside GWF files
4096 Hz Sampling Rate 16386 Hz Sampling Rate
{ifo}:GWOSC-4KHZ_R1_STRAIN {ifo}:GWOSC-16KHZ_R1_STRAIN
{ifo}:GWOSC-4KHZ_R1_DQMASK {ifo}:GWOSC-16KHZ_R1_DQMASK
{ifo}:GWOSC-4KHZ_R1_INJMASK {ifo}:GWOSC-16KHZ_R1_INJMASK

Where {ifo} = H1, L1, V1, or G1

Older releases of O1 and O2 data

Strain data for some of these events have been previously released as:

Strain files for the same time period from different releases may have small differences due to different versions of calibration, data cleaning, and/or differences in how the down-sampling was applied to produce 4096 Hz files. Data quality segment information has also been updated, including times when low amplitude continuous wave injections were active.

Previously released parameter estimation samples include:

  • O1 Binary Black Hole Mergers: see T1800235
  • Binary Neutron Star Merger GW170817 - see results from two publications: P1800115 | P1800061

Segments / Data Quality

Data quality categories are as defined in the O1 data release. Continuous Wave injections (CW) are present during most events at a very low amplitude, and do not interfere with transient detection. Data availability, data quality, and hardware injection segments are available:

  • In the data files, through bit masks with this bitmask definition. This definition is consistent across all events in this catalog.
  • Through the Timeline web interface:

Hardware Injections

The data released around marginal trigger 151012A contains a number of transient hardware injections, which are simulated signals intentionally added. Details may be found linked from the O1 Hardware Injection Page. Segments for hardware injections at times around each event in this catalog are available through the Timeline interface (linked above).

Calibration Versions

The following channels and frame types are packaged as the public strain data. The 16 kHz strain vector exactly matches the source channels for times where DATA are available: 

Times during O1:
{   'H1':('H1:DCS-CALIB_STRAIN_C02', 'H1_HOFT_C02'), 
    'L1':('L1:DCS-CALIB_STRAIN_C02', 'L1_HOFT_C02'),  
    'V1':('V1:Hrec_hoft_V1O2Repro1A_16384Hz','V1O2Repro1A'),
    'G1':('G1:DER_DATA_H', 'G1_RDS_C01_L3') } 

Times during O2:
{   'H1':('H1:DCH-CLEAN_STRAIN_C02', 'H1_CLEANED_HOFT_C02'), 
    'L1':('L1:DCH-CLEAN_STRAIN_C02', 'L1_CLEANED_HOFT_C02'), 
    'V1':('V1:Hrec_hoft_V1O2Repro2A_16384Hz', 'V1O2Repro2A'), 
    'G1':('G1:DER_DATA_H', 'G1_RDS_C01_L3' ) }

The DOI for this page is https://doi.org/10.7935/82H3-HH23

Release Notes

  • First release: December 1, 2018
  • Add link to skymaps: December 20, 2018
  • Add links to PSDs & GCNs, and made cosmetic edits to documentation: January 22, 2018
  • Added DOI: February 5, 2019
  • Added link to Calibration Uncertainty: February 6, 2019
  • Added link for GW170817 glitch subtraction: February 22, 2019
  • Added note for special cases of GW170817 and GW170608: March 26, 2019
  • Added link to GW170608 background data set: May 31, 2019
  • Added links to previous PE results: December 16, 2019
  • Updated parameter values to match published version: February 19, 2020
  • Added link to search pipeline trigger data: February 25, 2020
  • Updated name for final mass to match current convention: October 15, 2020
  • Updated links to segment lists: July 15, 2021
  • Added p-astro values and updated docs: November 12, 2021
  • Added brief documentation for GWTC-2.1 reanalysis of PE results: January 19, 2022