Editing Spacecraft Event Time (section)

===Calculating SCET===

Determining the Spacecraft Event Time involves taking the time at Earth and adding or subtracting the signal travel time, depending on whether the signal is being sent to or received from the spacecraft.  For events transmitted from the spacecraft to Earth, the SCET of an event on the spacecraft can be defined as equal to the ERT (Earth-Received Time) minus the OWLT (One-Way Light Time).<ref>Basics of Space Flight Glossary; JPL/NASA</ref>  For events transmitted from Earth to the spacecraft, the calculation is TRM (transmission time<ref>{{Cite web |title=Synonyms for Transmission Time |url=http://www.thesaurus.net/transmission%20time |website=Thesaurus.net |language=en}}</ref>) plus OWLT.  For example, if a signal were received on Earth at exactly 11:00 UTC from a spacecraft showing that it had just completed a maneuvering thrust, but the spacecraft was four light-hours away from Earth (the distance of the [[New Horizons]] spacecraft at one point as it approaches [[Pluto]]), the SCET time of the thrust maneuver would have been four hours earlier, at 07:00.

'''Spacecraft Event Time''' in [[Coordinated Universal Time|UTC]] is also known as '''Orbiter UTC''', and Earth-received time as '''Ground UTC'''.