A quantity involved in the visual observation of a source of light when viewed directly from such a distance that the apparent diameter is inappreciable. The point brilliance is measured by the illuminance produced by the source on a plane at the observer's eye normal to the direction of the source.
Unit: lux (lx)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM