Add GMT-12 (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-12 (Greenwich Mean Time) is GMT-12, whose offset is GMT-12 from Greenwich Mean Time (GMT).

The IANA timezone identifier for GMT-12, Greenwich Mean Time is "GMT-12"

It currently does not observe Daylight Savings Time.