O3 Auxiliary Channel Data Release

Data Set

The LIGO instrument at each site uses a large number of sensors to track the state of both the instrument and the surrounding environment.

A subset of those sensors (channels) are used as part of astrophysical analyses by the LIGO-Virgo-KAGRA collaboration. The particular subset of channels provided here in the main release (AUX_AR1) has been used to remove additional noise from LIGO data or to improve the quality of the astrophysical analyses.

A second set of channels (AUX_CLN) is also included in this data release. These channels were not used for an LVK analysis, but instead, were requested for an exploratory study of noise subtraction.

Channel Names

Each channel has a name using this structure: [IFO]:[SYSTEM]-[NAME], where:

  • [IFO] is the instrument (e.g., H1 refers to LIGO Hanford)
  • [SYSTEM] is an acronym for the instrument subsystem (e.g., PEM means "Physical Enviornment Monitor")
  • [NAME] is a name describing the channel (often containing more acronyms).

Channel List

This data set includes 40 channels from LIGO Hanford and 46 channels from LIGO Livingston, that were used in O3 astrophysical analyses. The data set has a total size of 13 TB. This data set includes channels that were used to create data quality flags, to subtract instrumental noise from the strain data, and to measure the amount of correlated noise between the gravitational-wave detectors. Additional details about how each of these channels was used in the data analysis can be found in the Channel List.

Channel List

Data Access


Data may be accessed from a network data server (NDS2) using the NDS2 client or GWpy. The following code can be used to download data (substitute any channel name that is a part of this data release):

from gwpy.timeseries import TimeSeries
data = TimeSeries.fetch('L1:ISI-GND_STS_ITMY_Z_BLRMS_30M_100M', start=1266624018, end=1266624618, host='nds.gwosc.org')

See the Data Access Example Code for additional examples.


This data release is also available via CernVM-FS, under the directory gwosc.osgstorage.org. If accessing large amounts of data, and/or working on a computing cluster, CernVM-FS is recommended as the preferred option for data access. This data release has frame type AUX_AR1.

cd /cvmfs/gwosc.osgstorage.org/gwdata/O3AUX/AUX_AR1


Data are available at times when the LIGO detectors are marked ANALYSIS_READY

Download Segment Lists:

Data for a small amount of time are missing, due to failures of the low-latency calibration pipeline. Data is not available during the following time segments (the start and stop times of each segement are listed as [start ... stop)):

  • Missing times for H1:
     [[1239130112 ... 1239134208)]
  • Missing times for L1:
     [[1247261568 ... 1247261824)
     [1266183936 ... 1266185600)
     [1267377472 ... 1267377600)
     [1267377664 ... 1267377728)
     [1267556672 ... 1267557056)
     [1267559296 ... 1267559424)
     [1267564160 ... 1267564480)
     [1268516633 ... 1268516672)]


Tutorials that show examples of different applications of this data set can be found in the Tutorials Git Repository.

Additional channels for noise cleaning (AUX_CLN)

In June of 2023, researchers at the Institute for Advanced Study requested a release of 16 additional channels from both LIGO instruments during O3, with the intent to study noise subtraction methods. These channels were added to the data release on January 31, 2024. These additional channels are available both via NDS2 and in CernVM-FS using the frame type AUX_CLN. The release covers a few months of O3.

References that describe the use of these channels

Additional references


This dataset has DOI: 10.7935/3bh6-0k98


This data release is the first of its kind. Is it useful for your research? How could it be improved? Please contact us with any feedback.

Revision History

  • Feb 21, 2023: First release
  • Jan 31, 2024: Adding AUX_CLN release