Add GMT (Greenwich Mean Time) to your list and use my-locations table to visually convert it's time to another timezone or city time.
Mouse over the colored hour-tiles and glance at the hours selected by the column.

Current time zone for GMT (Greenwich Mean Time) is GMT, whose offset is GMT+0 from Greenwich Mean Time (GMT).

The IANA timezone identifier for GMT, Greenwich Mean Time is "GMT"

It currently does not observe Daylight Savings Time.