Similar to IST

GA - Greenwich Atomic name used in UK for UTC prior to 1964
GBT - Great British Time
GCT - Greenwich Civil Time suggested replacement name, in 1925, for GMT
GeT - Greenwich Electronic Time British name for UTC
GMAT - Greenwich Mean Astronomical Time UT - 12 hours
GMT - Greenwich Mean Time replaced by Universal Time in 1928, and UTC in 1960
GST - Greenwich Sidereal Time

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