Auxiliary Channel Three Hour Release

Data Set

A large number of sensors are used to record the state of the LIGO instruments and their enviornment. This data release contains sensor data recorded in around 500 channels at each LIGO site. These data represent three hours of time centered on GW170814 (GPS 1186736512 — 1186747264). Strain data from the same period are available in the O2 Data Release.

Download Data

The data are available as down-sampled HDF5 files [19 GB], or full sample rate GWF files [68 GB]:

HDF5 Data GWF Data

Data may also be accessed from a network data server (NDS2) using the NDS2 client or GWpy:

from gwpy.timeseries import TimeSeries
data = TimeSeries.fetch('L1:LSC-DARM_OUT_DQ', start=1186741850, end=1186741870, host='')

See the NDS2 Example Code for details.

Example Software

Example software is available in an associated git repo. To work with GWF files, see the software page.

Channel Descriptions

This data set is designed to be used for subtracting noise sources - especially controls noise - from LIGO data. Channels included in this set are those most likley to include a coupling to the gravitational wave strain channel, and so are possible sources of noise.

The Channel List shows each channel with a few properties:

  • Channel name
  • Desired sample rate: The sampling rate in the down-sampled, HDF5 data
  • Notes: A brief note explaining the meaning of the data in the channel
  • Calibration: Where available, a calibration factor is included. Most channels are not calibrated.
  • Units: Where available, the units corresponding to the calibration factor

In some cases, data for a given channel may not be available. These are marked "invalid" in the HDF5 files, and the corresponding channel may be absent from the GWF files. Unavailable channels may correspond to sensors that are not present at a particular site or not operational at a particular time.

Channel names including PEM are part of the "Physical Enviornment Monitoring" system, described at For information about other channel names, see the references below.



This data release is the first of its kind. Is it useful for your research? How could it be improved? Please send feedback to


The first release of these data included a bug in the down-sampling code, which led to transient artifacts at the boundaries between files in the HDF5 version. This has been corrected as of June 29, 2021, and "v2" of the HDF5 files are available for download. The GWF files and NDS2 streaming data were not impacted by this and have not been changed.

Version history:

  • First release: August 27, 2020
  • Fixed down-sampling bug in HDF5 files: June 29, 2021