4 ms·
GPS satellites comes to mind.
by treve 4y ago
GPS satellites comes to mind.
- PeterisP 4y agoYes, GPS satellites are a good example. We don't keep a "GPS time zone"[1] or define "GPS second" to account for that - we calculate the dilation the satellite gets due to relativity (e.g. https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Relativity https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...), treat that dilation as a predictable "error" from the correct (Earth) time, and adjust for that. [1] There actually is a time zone called "GPS time", however, that explicitly doesn't include the relativistic effects, it has the same second length as UTC, not what an atomic clock on a GPS satellite would measure, it differs from UTC only in how it counts days - in "GPS time" there's always 86400 seconds in a day and leap seconds are never added to adjust for Earth's rotation speed.
- zokier 4y agoThe same way it makes sense for GPS to use Earth-based timescale instead of something like TCG[1] or TCB[2], it makes sense for lunar positioning to use lunar based timescale. > There actually is a time zone called "GPS time", however, that explicitly doesn't include the relativistic effects It does include the relativistic effects of Earth [1] https://en.wikipedia.org/wiki/Geocentric_Coordinate_Time https://en.wikipedia.org/wiki/Geocentric_Coordinate_Time [2] https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time