R. Stone

The LSC glitch group: monitoring noise transients during the fifth LIGO science run

The LIGO Scientific Collaboration (LSC) glitch group is part of the LIGO detector characterization effort. It consists of data analysts and detector experts who, during and after science runs, collaborate for a better understanding of noise transients in the detectors. Goals of the glitch group during the fifth LIGO science run (S5) included (1) offline assessment of the detector data quality, with focus on noise transients, (2) veto recommendations for astrophysical analysis and (3) feedback to the commissioning team on anomalies seen in gravitational wave and auxiliary data channels. Other activities included the study of auto-correlation of triggers from burst searches, stationarity of the detector noise and veto studies. The group identified causes for several noise transients that triggered false alarms in the gravitational wave searches; the times of such transients were identified and vetoed from the data generating the LSC astrophysical results.

Environmentally induced nonstationarity in LIGO science run data

NoiseFloorMon is a data monitoring tool (DMT) implemented at the LIGO sites to monitor instances of non-stationarity in the gravitational-wave data that are correlated with physical environmental monitors. An analysis of the fifth science run is nearly complete, and test runs preceding the sixth science run have also been analyzed. These analyses have identified time intervals in the gravitational-wave channel that indicate non-stationarity due to seismic activity, and these intervals are referred to as data quality flags. In the analyses conducted to date the majority of time segments identified as non-stationary were due to seismic activity at the corner station and the x-arm end station. We present the algorithm and its performance, and discuss the potential for an on-site pipeline that automatically generates data quality flags for use in future data runs.