1. Airport ID: specify a 3- or 4-letter designator for a U.S. or International Airport. Capitalization is not important.
2. Airport name. Several names are stored for some airports.
If an exact match cannot be found then the closest match will be used, where "close" means exact except "Muni" instead of "Int'l", "Field" instead of "Executive", etc.
3. City, State: city and state separated by a comma.
The State is optional. For airports outside of the U.S., specify the country in the State field. Use the two-letter abbreviation for US states. Presently only Cities with airports are recognized.
4. Latitude, Longitude: Either of the following formats will work:
N42-44 W071-35 or S42.74 E071.6.
Seconds are accepted and some other formats are accepted.
If there are several time zones for the state or country that sunrise and sunset are to be computed for and "Automatic" returned the wrong one (it defaults to Eastern) then try selecting "Central", "Pacific/West", or "Mountain/Other" in order.
A Custom time zone may entered. Modern UNIX time zone syntax is recognized. This includes ("GMT+x" or "GMT-x", where x is hours west (+) or east (-) of GMT (England). Alternatively, it may be "ABCxDEF", where ABC are any letters displayed for standard (winter) time and DEF are displayed if summer time, and x is described above. US daylight saving time (summer time) rules will be used in this case.
Note: in some cases US or European rules for when to be on daylight saving time (summer time) will be used inappropriately for other countries.
You also can use the Custom time zone box to have the sunrise/sunset times for some other place given in your time zone. For example, if you are in the US Eastern time zone specify "US/Eastern" as the Custom time zone. (Note that this is one of the time zones listed below.)
If Custom time zone is specified then the other time zone buttons are ignored.
Custom time zone may also be any of the following:
WET CET EET GB-Eire US/Alaska US/Central US/Hawaii US/Pacific US/Aleutian US/East-Indiana US/Michigan US/Pacific-New US/Arizona US/Eastern US/Mountain US/Samoa Canada/Atlantic Canada/East-Saskatche Canada/Mountain Canada/Pacific Canada/Central Canada/Eastern Canada/Newfoundland Canada/Yukon Australia/LHI Australia/North Australia/South Australia/Victoria Australia/Yancowinna Australia/NSW Australia/Queensland Australia/Tasmania Australia/West
"Republic of" and similar are removed when they are not universally used.
The word "Island" or "Islands" usually is retained when commonly used and should not be abbreviated. Sometimes "Island" and "Islands" have been accidentally swapped in the database.
The words "Saint" and "Sainte" usually is abbreviated as "St" or "Ste" or "St." or "Ste." but sometimes is spelled out. Most combinations are recognized.
"Fort" frequently is abbreviated as "Ft" or "Ft.", depending on local custom. Most combinations are recognized.
Compass directions that are parts of names should be spelled out.
Therefore, at these high latitudes some events are listed as Does not occur. Since the various events (sunset, end of civil twilight, etc.) are officially defined as when the sun is at various positions in the sky, it is possible for some of these events to occur and some not to. (The sun may dip down enough for sunset but not for the end of civil twilight.)
If the sun "just barely" rises on a given day it might have shifted just enough to "just barely not" set that day, and likewise for other "mirror image" events. It is also possible for rounding errors to cause one and not the other to be listed. (You can try a date 15 days before and after to verify these.)