O1 Transient Hardware Injections
During Advanced LIGO's first observing run (O1),
simulated signals were added to the
LIGO detectors for testing and calibration. The simulated signals are
known as hardware injections, because they were created by manipulating
mirrors in the arms of the interferometers. Times of hardware injections
are marked in LIGO data files by injection data quality channels. See the
injection bit mask
Further details on hardware injections are in Validating gravitational-wave detections: The Advanced LIGO hardware injection system available from arXiv:1612.07864 [astro-ph.IM] and doi:10.1103/PhysRevD.95.062002.
Compact Binary Coalescence Injections
Compact Binary Coalescence (CBC) injections were added at planned
times throughout O1. Each CBC injection used a waveform
to approximate the signal expected from the inspiral, merger, and
ringdown of a binary
neutron star system, a neutron star with a black hole, or a binary
black hole. A spectrogram of a sample injection can be seen in the image
on this page.
Burst injections include ad-hoc transient injections, as described for
S6 burst injections
Stochastic and Detector characterization Injections
These injections all happened in times when GWOSC does not have data, i.e. the DATA bit is off.
Tables of Transient Injections
Each injection is listed with the following information:
- GPS: The GPS time of the end of the injection, or the "merger" time, in GPS seconds
- Mass1 / Mass2: The mass, in solar units, of each compact object
- Dist: The distance to the simulated source in Mpc.
- Exp. SNR: The expected SNR of the injection.
- Rec. SNR: The recovered matched-filter SNR of the injection,
as described in
Allen et al. (2011).
SNRs from 1-5 are typical for times with no signal.
- Type: The category of transient
- Waveform: The name of the waveform used internally by the LIGO Scientific Collaboration.
Tables of transient injections:
Lists of O1 transient injections:
Segment Lists when Injections are Not Present
In addition to the log files shown above, information about injection-free
times is available in segment lists
from the Timeline
- The NO_CBC_HW segment lists show times when CBC injections were
- The NO_BURST_HW segment lists show times when Burst injections were
- The NO_CW_HW segment lists show times when CW injections were
- The NO_STOCH_HW segment lists show times when stochastic injections were
- The NO_DETCHAR_HW segment lists show times when detector characterization injections were not present:
O1 Continuous Wave Hardware Injections
Continuous Wave Injections
Continuous Wave (CW) injections (also known as pulsar injections) were added
throughout O1. Each CW injection corresponds to a simulation
of a gravitational wave signal of the form expected from a rapidly rotating,
isolated neutron star (often observed as a radio pulsar).
The CW injection system was not active at all times during the run.
For a list of times when this system was NOT active, see the
O1 CW no-Injection Timelines, or the segment lists (
The parameters are defined as in
The parameters f0 and phi0 are both defined at a reference time (epoch)
which are chosen to be
to either the beginning of LIGO's 3rd science run (S3, GPS 751680013 == 2003-11-01T00:00:00 UTC), or at the start of Virgo's 2nd run (VSR2, GPS 930582085 == 2009-07-02T15:01:10). Two additional parameters are also listed for each simulated pulsar:
Aplus = 0.5*h0*(1 + cos2
Across = h0*cos(iota)
For more information: