Arc of visibility of navigation light.
<div style="display:inline-block;padding:0 3px;background-color:#CCF">Original:</div> <div style="display:inline-block;padding:3px 0;"><a href="//commons.wikimedia.org/wiki/User:Claudio_Elias" title="User:Claudio Elias">Claudio Elias</a></div> <div style="display:inline-block;padding:0 3px;background-color:#CCF">Vector: </div> <div style="display:inline-block;"><a href="//commons.wikimedia.org/wiki/User:ThelmOSO" title="User:ThelmOSO">ThelmOSO</a></div>
Own work based on: <a href="//commons.wikimedia.org/wiki/File:VisibilityArc.PNG" title="File:VisibilityArc.PNG">VisibilityArc.PNG</a>