Hi all,

We are using cyclic_time_shift function in the tutorial 2.2 for shifting the wave-form(template). what is the science behind it how it calculate the approximate merger location, for calculating the SNR shifting is needed? i’m a bit confused about it anyone help me to understand it properly.

Hi @Rao , the use of cyclic_time_shift is required because of the way in which the matched_filter works. Using the cyclic_time_shift you ensure that the merger is at the beginning of your template so that the peak on the snr plot is at the time of the merger. If you don’t do the cyclic shift, the code will tell you that there is a match between tha data and the template at the starting of the template so about 1 s before the merger time.

A way to help the intuition is to calculate the snr both with hp and with tempate (i.e. hp after the cyclic_time_shift). You will find a similar plot but the time of the merger is different: 1126259462.4 s when you use the template and 1126259461.8 when you use hp, so earlier as expected.

Hope this helps :slight_smile: