% time of local noon % Computed from your time zone and longitude: % 1.Compute your longitude in decimal form: degrees + (minutes/60) + (seconds/3600). If % you're in the Eastern Hemisphere, make this a negative number. dms=input('type in degrees, minutes and seconds'); deg=dms(1); min=dms(2); sec=dms(3); e=input('Are you in the Eastern Hemisphere? (yes - 1, no - 0) '); long=deg+min/60+sec/3600; % 2.Compute your "standard meridian" (the longitude of the center % of your time zone): % difference in hours between your time and "Universal time" % (Greenwich or Zulu time) % times 15 (for example, the US Central time zone is six hours different, % times 15 means that % the "standard meridian" for the Central Time Zone is 90 degrees). % Make this a negative number if you're in the Eastern Hemisphere. tz=input('time zone: 1: eastern, 2: central, 3: mountain, 4: pacific '); sm=(tz+4)*15; % 3.Subtract the standard meridian from your longitude. dif=long-sm; % 4.Divide that difference by 15 to get the longitude deviation time % (the amount that your local % time is ahead or behind the clock time for your time zone) % 5.Add 0.123 to that time (the correction for the deviation between % the way our clocks/calendars work and the way the earth/sun work: % this is found in the current Almanac % For a given date - in this case, 0.123 for March 20th) dev=dif/15+0.123 % 6.Add the resulting number to 12 (or subtract it from 12 if it is % negative) to get the time of your local noon. noon=12+dev % 7.Convert the decimal number to hours, minutes, and seconds. whole=fix(noon) % 1.The whole number is the hours. % 2.Multiply the fraction by 60. The whole number is the minutes. left=(noon-whole)*60; min=fix(left); sec=(left-min)*60; % 3.Multiply the fraction by 60. The results is the seconds. disp('whole min sec'); disp([whole min sec]); % (Crazy system we have for time!) % % For example, in the case of Lancaster Pennsylvania, at longitude % 76 degrees, 17 minutes, and 0 seconds in the Eastern Standard Time % zone (5), the decimal longitude is 76.28, the standard meridian % is 75 degrees, the deviation in longitude is +1.28 degrees, % the deviation in time is +0.08, the correction is +0.12, the % local noon time is 12.20, which is 12:12 PM. So their Noon % Observations should start before 12:12 and end after that in order % to capture local noon.