The Echo Astronomical Timeclock (E-ATC) has a setting called Flickwarn. This feature will flash the lights in the Echo Space a short period of time before the Timeclock plays a Space Off event. By default, this is set to flash the lights two (2) minutes before the Space Off event is played. This allows plenty of time for a preset to be played from an Echo Preset or Inspire station, or an Echo Touch Controller, which will apply a Timed Hold on the Space Off event. This hold will last until the Hold Time has completed (default 120 minutes) and then the Echo Timeclock will sync the lights back to the current schedule.
During Flickwarn, the lights will drop to 0% for 500 milliseconds, or 1/2 second, then return to the previous state. The lights will only drop down once as a warning.
For more information, please see the Echo Timeclock Configuration Manual located here.