This attribute allows you to set the Set Mission Elapsed Time Epoch to Launch Epoch launch option.
Astrogator <Satellite Object Path> SetValue <Astrogator Object Path>.SetMETEpoch <Boolean>
Set this attribute to true to set the Mission Elapsed Time epoch to the Launch epoch when the MCS is run.
Astrogator */Satellite/Satellite1 SetValue MainSequence.SegmentList.Launch.Launch.SetMETEpoch true
STK Programming Interface 11.0.1