periodical announces new nautical charts and publications, new editions, cancellations, and changes to nautical charts and publications. It also summarizes events of the week as they affect shipping, advise mariners of special warning or items of general maritime interest, and includes selected accounts of unusual phenomena observed at sea. Distribution of Notices to Mariners is made weekly to all U.S. Navy and Coast Guard ships and to most ships of the merchant marines. The classified chart and publication correction system is based on Classified Notices to Mariners, published on an as-needed basis by the DMAHTC to inform mariners of corrections to classified nautical charts and publications. HAND CORRECTIONS Corrections on charts in writing should be kept clear of water areas as much as possible unless the objects referred to are on the water. When you are inserting written corrections, be careful not to obliterate any of the other information already on the chart. When cautionary, tidal, and other such notes are to be inserted, they should be written in a convenient but conspicuous place where they will not interfere with any other details. The year and number of each Notices to Mariners from which corrections have been made are to be entered in ink at the lower left corner of the chart. Temporary changes should be made in pencil. For more information on chart corrections, visit your local Quartermaster. AIDS TO NAVIGATION LEARNING OBJECTIVES: Identify and explain the aids to navigation, including lights, lighthouses, buoys, daybeacons, ranges, and fog signals. In piloting, a ship's position is determined by bearings or ranges of objects whose exact location is shown on the area chart. Such objects are aids to navigation, and may be natural or man-made. Examples of natural objects are prominent hills, rocks, and mountains. Man-made objects include buildings, TV towers, and smokestacks that are coincidentally located where they can be of assistance to a navigator. Aids to navigation are lighthouses, lightships, minor lights, buoys, and daybeacons. Aids are placed so that, insofar as possible, they provide a continuous and unbroken chain of charted marks for coast and channel piloting. Most harbors and some coasts are well marked with man-made aids to navigation, yet no attempt has ever been made to mark every mile of the world's coastline. Such marking would be impractical because many regions are seldom navigated. In some areas, the lack of artificial aids makes it necessary to use landmarks. LIGHTS A ship cannot suspend piloting operations when darkness falls and daytime navigational aids no longer can be seen. For this reason, aids to navigation are lighted whenever it is necessary. For purposes of identification, lights have individual characteristics regarding color, intensity, and system of operation. Some of a light’s characteristics may be printed near its symbol on the chart. Detailed information, including the height—which, combined with intensity and observer's height, determines the light's visibility—is set forth in either List of Lights or Light Lists. The DMAHTC publishes seven volumes of List of Lights. The volumes are divided geographically, but exclude the United States and its possessions. This list contains a description of lighted aids to navigation (except harbor-lighted buoys) and fog signals. Storm signals, signal stations, radio direction finders, and radio beacons located at or near lights are also mentioned in this list. Lights located in the United States and its possessions are described in Light Lists, published by the U.S. Coast Guard. LIGHT CHARACTERISTICS White, red, green, and yellow are the four standard colors for lights on aids to navigation. The significance of the different colors is important chiefly with regard to channel buoys; this significance is discussed later in the sections dealing with buoys. Some navigational lights are fixed, meaning they burn steadily. The most important lights, however, go through repeated periods of systematic changes of light and darkness. Those characteristics of a navigational light are the most valuable for 9-7