Figure 10:

Normalized spectrograms of GW150914 in LIGO-Hanford (left) and LIGO-Livingston (right) h(t) data with the same central GPS time. The data at both detectors exhibited typically low levels of noise around the time of the event; the signal, offset by ~7 ms between detectors, was recovered by a matched-filter CBC search with a combined detector signal-to-noise ratio of 24 [1, 2], by the coherent burst search with a coherent network SNR of 20 [3], and by Omicron with a single-detector SNR of 12 in Hanford and 9 in Livingston. The time-frequency morphology of the event is distinct from the known noise sources discussed in Section 3.