Add Ha'atu'a (Tonga) 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 Ha'atu'a (Tonga) is Pacific/Tongatapu, whose offset is GMT+13 from Greenwich Mean Time (GMT).

The IANA timezone identifier for Ha'atu'a, Tonga is "Pacific/Tongatapu"

It currently does not observe Daylight Savings Time.