# 4.6.1. bright_lights¶

Code to determine the brightness function of seismic data according to a three-dimensional travel-time grid. This travel-time grid can be generated using the grid2time function of the NonLinLoc package by Anthony Lomax which can be found here: NonLinLoc. NonLinLoc is not distributed within this package but it is a very useful stand-alone library for seismic event location.

This code is based on the method of Frank & Shapiro 2014.

 brightness Calculate the brightness function for a single day. coherence Determine the average network coherence of a given template or detection.
 _rms Calculate RMS of array. _rm_similarlags Remove nodes that have a very similar network moveout to another node. _resample_grid Resample the lagtime grid to a given volume. _read_tt Read in .csv files of slowness generated from Grid2Time. _cum_net_resp Compute the cumulative network response by reading saved energy .npy files. _node_loop Internal function to allow for brightness to be paralleled. _find_detections Find detections within the cumulative network response.