Data release for event GW170817

This page has been prepared by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration.

The event occurred at GPS time 1187008882.43 = August 17 2017, 12:41:04.43 UTC.

The event was observed by data from the LIGO Hanford (H1), LIGO Livingston (L1) and Virgo (V1) detectors.

Because the Binary Neutron Star signal spends much more than 32 seconds in the detector's frequency band, data products of 32 seconds in duration are not being distributed with GW170817.

This page serves as a supplement to the paper GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral, available from LIGO DCC and doi:10.1103/PhysRevLett.119.161101.

Gravitational-Wave Strain Data

Strain data after noise subtraction

After data collection, several independently-measured terrestrial contributions to the detector noise were subtracted from the LIGO data using Wiener filtering. This subtraction removed calibration lines and 60 Hz AC power mains harmonics from both LIGO data streams. At times near GW170817, the sensitivity of LIGO-Hanford was particularly improved by the subtraction of laser pointing noise; several broad peaks in the 150 - 800 Hz region were effectively removed, increasing the Binary Neutron Star horizon distance of that detector by 26%. In addition, a short instrumental noise transient appeared in the LIGO-Livingston detector 1.1 s before the coalescence time of GW170817. This transient noise, or glitch, produced a very brief (less than 5ms) saturation in a digital-to-analog converter. This glitch has been removed from the noise subtracted data. For reference:

Notes:

  • Below are links to strain h(t) time series centered at GPS 1187008064.
  • All cleaned data files have been shortened to a total duration of 2048 seconds.
  • The H1 and L1 noise subtraction procedure introduces excess noise at frequencies below 20 Hz. Users should restrict analysis to frequencies above 20 Hz.
  • The H1 cleaned data include times corrupted by a window function used as part of the cleaning procedure. This impacts roughly the last 150 seconds of the H1 cleaned data.
  • Due to V1's smaller coupling factor to gravitational waves from the sky direction of GW170817, and the lower detector sensitivity, the signal is below the noise level and is thus not visible in the Virgo data.
  • These LIGO and Virgo data were used to produce parameter estimation results in the papers: arxiv:1805.11579 and arxiv:1805.11581
  • These LIGO data were used to produce parameter estimation results in the paper Phys. Rev. Lett. 119, 161101
  • The files and some technical notes may all be found in LIGO P1700349
  • md5 checksums may be used to ensure files are correctly downloaded.
After noise subtraction, 4096 Hz H1 L1 V1
2048 seconds (event signal reaches peak amplitude 1842.43 seconds ± 30 msec from start†) hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz
After noise subtraction, 16384 Hz H1 L1 V1
2048 seconds (event signal reaches peak amplitude 1842.43 seconds ± 30 msec from start†) hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz

† The ± 30 msec window for peak amplitude is due to different arrival time in each of the three detectors.

Strain data before noise subtraction

These files contain data before noise subtraction. These data were produced in low-latency, and used by the search pipelines to evaluate event significance. A short instrumental noise transient appeared in the LIGO-Livingston detector 1.1 s before the coalescence time of GW170817. This transient noise, or glitch, produced a very brief (less than 5ms) saturation in a digital-to-analog converter. This glitch is present in the strain data before noise subtraction. To evaluate the significance of GW170817, the CBC search analyses applied a window function to zero out the data around the glitch. This Tukey window uses the following parameters: zero the data +/- 0.1 seconds (0.2 seconds total in length) around the glitch time 1187008881.389 and the roll-off time is 0.5 seconds either side of the zeroed data. This inverse Tukey window is presented in Figure 2 of the GW170817 discovery paper. Some Burst searches may use a CAT2 data quality flag to remove this glitch from search results. There is an active Burst CAT2 data quality flag at LIGO-Livingston starting at 1187008880 and extending to 1187008884. In this case also GEO600 data are released. The GEO600 calibration uncertainty is estimated to be within 15% in amplitude and 15 deg in phase in the 1-4 kHz band.

Notes:

  • Below are links to strain h(t) time series centered at GPS 1187008882.
  • These Virgo data were used to produce parameter estimation results in the paper Phys. Rev. Lett. 119, 161101
  • The files and some technical notes for LIGO and Virgo may all be found in LIGO P1700337
  • GEO600 data files have the label "G1".
  • G1 files may be found in LIGO P1800187
  • md5 checksums may be used to ensure files are correctly downloaded (the md5 checksums for the G1 files may be found here).
  • In GEO600, the signal is below the noise level because of the lower detector sensitivity and is thus not visible in the G1 data. These data have not been used for the discovery of the GW170817 event and the subsequent parameter estimation analyses. However, GEO600 data were used in the paper arxiv:1805.11579 to place upper limits on the amplitude and spectral energy density of a possible post-merger signal. This analysis uses only the high-frequency signal component and only 1 s of data around the coalescence time of the merger.
  • GEO600 data are characterised by an excess noise at low frequency for about 100 seconds after the start of the second data segment (after GPS 1187008219).
  • For G1, the data quality flag 'DATA' refers to when the detector was UP. At the time of the event the detector was not in science mode. The reason for GEO data quality not being in Science mode is because of a software maintenance investigation regarding an issue with the squeezer phase loop error point which was introducing technical noise below 1kHz. Data quality above 1kHz (the relevant frequency band for the current study that used GEO data) was not compromised.
Before noise subtraction, 4096 Hz H1 L1 V1 G1
4096 seconds (event signal reaches peak amplitude 2048.43 seconds ± 30 msec from start†) hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz
Before noise subtraction, 16384 Hz H1 L1 V1 G1
4096 seconds (event signal reaches peak amplitude 2048.43 seconds ± 30 msec from start†) hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz hdf5 gwf txt.gz

† The ± 30 msec window for peak amplitude is due to different arrival time in each of the three detectors.

Sky Localization

Source localization data for GW170817 are available as LIGO G1701985

Rapid triggers from LIGO data are available as GCN notices for GW170817

Parameter Estimation Samples

Parameter estimation samples: P1800115 | P1800061

See the About the Detectors Page to learn about the instruments and collaborations.

The technical details provides detailed usage notes.

Feel free to contact us with any questions.

Revision History

  • October 19, 2017: Added note regarding glitch in L1 data.
  • June 1, 2018: Added note about window function visible in last 150 seconds of H1 cleaned data.
  • Aug 28, 2018: Added link to PE samples
  • Oct 23, 2018: Added GEO600 data and corresponding notes in the section "Strain data before noise subtraction"
  • Dec 16, 2019: Added links to PE samples