# 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.

copyright: | EQcorrscan developers.
license: | GNU Lesser General Public License, Version 3 (https://www.gnu.org/copyleft/lesser.html)

## 4.6.1.1. Classes & Functions

`brightness` | Calculate the brightness function for a single day.
`coherence` | Determine the average network coherence of a given template or detection.

## 4.6.1.2. Private Functions

Note that these functions are not designed for public use and may change at any point.

`_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.