See the cross-correlation | See the bandpassed data cross-correlation
correlated_raw = np.correlate(data, template, 'valid') correlated_passed = np.correlate(data_pass, template, 'valid') plt.figure() plt.plot(correlated_raw) plt.figure() plt.plot(correlated_passed)
The time axis on the cross-correlation represents the off-set between the data start time and the filter start time. So, we look for a peak at the time when the start of the template matches the data. In contrast, plotting the band-passed data shows a peak at the time when the signal is loudest, near the end of the template. Typically in LIGO, we report the coalescence time when the binary crosses the inner-most stable circular orbit (ISCO), near the end of the template.