Sec.  73.1720   Daytime.

   Operation is permitted during the hours between average monthly local
   sunrise and average monthly local sunset.

   (a) The controlling times for each month of the year are stated in the
   station's instrument of authorization. Uniform sunrise and sunset times are
   specified for all of the days of each month, based upon the actual times of
   sunrise and sunset for the fifteenth day of the month adjusted to the
   nearest quarter hour. Sunrise and sunset times are derived by using the
   standardized procedure and the tables in the 1946 American Nautical Almanac
   issued by the United States Naval Observatory.

   (b) [Reserved]

   [ 43 FR 45849 , Oct. 4, 1978]