# Data release for event GW150914

This page has been prepared by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration to inform the broader community about a confirmed astrophysical event observed by the gravitational-wave detectors, and to make the data around that time available for others to analyze.
There is also a **technical details** page about the data linked below, and
feel free to **contact us**.
This dataset has the Digital Object Identifier (doi) https://doi.org/10.7935/K5MW2F23

## Summary of Observation

The event occurred at GPS time 1126259462 == September 14 2015, 09:50:45 UTC.
The false alarm rate is estimated to be less than 1 event per **203,000 years**, equivalent to a
significance of **5.1 sigma**.
The event was detected in data from the
LIGO Hanford and
LIGO Livingston
observatories.

How to Use this Page

**Click on the section headings below to show available data files.**- There are lots of data files available in the sections below, look for the word
**DATA**.

- Click on each thumbnail image for larger image.

- See the papers linked below for full information, references, and meaning.
- Many of the data files linked below have heterogeneous formatting; if you have any questions, please contact us.

*The G150914 detection paper:*

## Observation of Gravitational Waves from a Binary Black Hole Merger

See also the paper "Binary Black Hole Mergers in the First Advanced LIGO Observing Run", LIGO DCC, arXiv, or Phys. Rev. X.

The Estimated source parameters below have been updated to come from this latter paper.

These papers and all the companion papers can also be found at papers.ligo.org.

## Estimated source parameters

Quantity | Value | Upper/Lower error estimate | Unit |
---|---|---|---|

Primary black hole mass | 36.2 | +5.2 -3.8 | M sun |

Secondary black hole mass | 29.1 | +3.7 -4.4 | M sun |

Final black hole mass | 62.3 | +3.7 -3.1 | M sun |

Final black hole spin | 0.68 | +0.05 -0.06 | |

Luminosity distance | 420 | +150 -180 | Mpc |

Source redshift, z | 0.09 | +0.03 -0.04 | |

Energy radiated | 3.0 | +0.5 -0.5 | M sun |

TABLE I. Estimated source parameters for GW150914. We report the median value as well as the range of the 90% credible interval. Masses are measured in the source frame; to convert masses to detector frame, multiply by (1 + z). The source redshift assumes standard cosmology.

click for DATA |
click for DATA (L1 only) |

click for DATA (Numerical relativity) |
click for DATA (Numerical relativity) |

click for DATA |
click for DATA |

FIG. 1. The gravitational-wave event GW150914 observed by the LIGO Hanford (H1, left column panels) and Livingston (L1, right column panels) detectors. Times are shown relative to September 14, 2015 at 09:50:45 UTC. For visualization, all time series are filtered with a 35–350 Hz band-pass filter to suppress large fluctuations outside the detectors’ most sensitive frequency band, and band-reject filters to remove the strong instrumental spectral lines seen in the Fig. 3 spectra.

- Top row, left: H1 strain. Top row, right: L1 strain. GW150914 arrived first at L1 and 6.9 (+0.5 −0.4) ms later at H1; for a visual comparison the H1 data are also shown, shifted in time by this amount and inverted (to account for the detectors’ relative orientations).
- Second row: Gravitational-wave strain projected onto each detector in the 35–350 Hz band. Solid lines show a numerical relativity waveform for a system with parameters consistent with those recovered from GW150914 confirmed by an independent calculation. Shaded areas show 90% credible regions for two waveform reconstructions: one that models the signal as a set of sine-Gaussian wavelets and one that models the signal using binary-black-hole template waveforms. These reconstructions have a 95% overlap.
- Third row: Residuals after subtracting the filtered numerical relativity waveform from the filtered detector time series.
- Bottom row: A time-frequency decomposition of the signal power associated with GW150914. Both plots show a signal with frequency increasing with time.

Numerical relativity DATAReconstructed DATA |
separation DATAvelocity DATA |

FIG. 2. Left: Estimated gravitational-wave strain amplitude from GW150914 projected onto H1. This shows the full bandwidth of the waveforms, without the filtering used for Fig. 1. Right: The Keplerian effective black hole separation in units of Schwarzschild radii and the effective relative velocity.

Hanford DATA Livingston DATA |

FIG.3. The average measured strain-equivalent noise, or sensitivity, of the Advanced LIGO detectors during the time analyzed to determine the significance of GW150914 (Sept 12 - Oct 20, 2015). Hanford (H1) is shown in red, Livingston (L1) in blue. The solid traces represent the median sensitivity and the shaded regions indicate the 5th and 95th percentile over the analysis period. The narrowband features in the spectra are due to known mechanical resonances, mains power harmonics, and injected signals used for calibration.

Search Result C3 DATASearch Background C3 DATA Search Result C2 C3 DATA Search Background C2 C3 DATA |
Search Results DATA |

FIG. 4. Search results from the generic transient search (left) and the binary coalescence search (right). These histograms show the number of candidate events (orange markers) and the mean number of background events in the search class where GW150914 was found (black lines) as a function of the search detection statistic and with a bin width of 0.2. The scales on the top give the significance of an event in Gaussian standard deviations based on the corresponding noise background . The significance of GW150914 is greater than 5.1 σ and 4.6 σ for the binary coalescence and the generic transient searches, respectively. (Left): Along with the primary search (C3) we also show the results (yellow markers) and background (green curve) for an alternative search that treats events independently of their frequency evolution (C2+C3). The classes C2 and C3 are defined in the text. (Right): The tail in the black-line background of the binary coalescence search is due to random coincidences of GW150914 in one detector with noise in the other detector. (This type of event is practically absent in the generic transient search background because they do not pass the time-frequency consistency requirements used in that search.) The blue curve is the background excluding those coincidences, which is used to assess the significance of the second strongest event candidate.

*The data from the observatories from which the science is derived:*

## Gravitational-Wave Strain Data

**Data usage notes**Please Read This First!**The data are provided in three formats.**HDF5 , Frame (.gwf), and gzipped ascii text. Many data analysis environments can read in data from HDF5 files, including Python (see the h5py package), MATLAB, C/C++, and IDL.- The
**md5 checksums**provide a check for downloaders that they have received the right file: run the Unix command "md5" (or "md5sum", depending on your OS) on your file and compare to LOSC published values. If different, try downloading again, and if the problem persists, contact us. **Technical details**especially about data quality and injections**Tutorials**to work with the strain data.

### Strain Data at 4096 Hz

Strain h(t) time series centered at GPS 1126259462:Duration | Hanford | Livingston |
---|---|---|

32 seconds approx 1 Mbyte | DATA hdf5 DATA gwf DATA txt.gz |
DATA hdf5 DATA gwf DATA txt.gz |

4096 seconds approx 134 Mbyte | DATA hdf5 DATA gwf DATA txt.gz |
DATA hdf5 DATA gwf DATA txt.gz |

### Strain Data at 16384 Hz

Strain h(t) time series centered at GPS 1126259462:Duration | Hanford | Livingston |
---|---|---|

32 seconds approx 4 Mbyte | DATA hdf5 DATA gwf DATA txt.gz |
DATA hdf5 DATA gwf DATA txt.gz |

4096 seconds approx 536 Mbyte | DATA hdf5 DATA gwf DATA txt.gz |
DATA hdf5 DATA gwf DATA txt.gz |

### Tutorial on Signal Processing with Gravitational-Wave Strain Data

### About the Instruments and Collaborations

### Observing Gravitational-Wave Transient GW150914 with Minimal Assumptions

### GW150914: First Results from the Search for Binary Black Hole Coalescence with Advanced LIGO

### Properties of the binary black hole merger GW150914

### The Rate of Binary Black Hole Mergers Inferred from Advanced LIGO Observations Surrounding GW150914

### Astrophysical Implications of the Binary Black-Hole Merger GW150914

### Tests of general relativity with GW150914

### GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

### Calibration of the Advanced LIGO detectors for the discovery of the binary black-hole merger GW150914

### Characterization of Transient Noise in Advanced LIGO Relevant to Gravitational Wave Signal GW150914

### High-energy Neutrino Follow-up Search of Gravitational Wave Event GW150914 with IceCube and ANTARES

### GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

*Sky location probability maps*

### Localization and broadband follow-up of the gravitational-wave transient GW150914

### Audio Files

There is a **technical details** page about the data linked above, and
feel free to **contact us**.

**Revision History**

- July 18, 2017: Added note explaining NR waveform is not precisely tuned.
- May 15, 2019: Corrected error in Energy Radiated to be ± 0.5, consistent with publication.