page_title: Light characteristic
section_title: Occulting light
hierarchical_section_title: Light characteristic / Light patterns / Occulting light
caption_attribution_description: English: The clockwork occulting mechanism from Coquet Island Lighthouse (which caused the lamp to appear to switch alternately off and on) is now on display at Souter Lighthouse.
context_page_description: A light characteristic is a graphic and text description of a navigational light sequence or colour displayed on a nautical chart or in a Light List with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. The graphic indicates how the real light may be identified when looking at its actual light output type or sequence. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing.
context_section_description: An occulting light is a rhythmic light in which the duration of light in each period is longer than the total duration of darkness. In other words, it is the opposite to a flashing light where the total duration of darkness is longer than the duration of light. It has the appearance of flashing off, rather than flashing on. Like a flashing light, it can be used for a single occulting light that exhibits only a single period of darkness or the periods of darkness can be grouped and repeated at regular intervals (abbreviated "Oc"), a group (Oc(3)) or a composite group (Oc(2+1)).
  The term occulting is used because originally the effect was obtained by a mechanism (e.g. a vertical or rotating shutter) periodically shading the light from view.
caption: Clockwork occulting mechanism formerly in use at Coquet Island Lighthouse.
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