The data recorded in the nautical almanac is usually recorded against UT (universal time or GMT). This is for convenience sake and when looking up any of the information one has to convert the zone time to GMT. In the case of the predicted times of sunrise, sunset, morning and evening twilight as well as the time of meridian passage of the sun, the times are tabulated in LMT.
Conversion of time.
The following is offered as a memory aid when converting from one time category to another:
“longitude west, Greenwich is best”. This means that when converting from LMT or Zone time in the western hemisphere to GMT you must add the difference.
For example: You are in zone P (+3) and your longitude is 45° W. Zone time is 1200 P. What is the GMT?
“longitude east Greenwich is least”. This means that when converting from LMT or Zone time in the eastern hemisphere to GMT you must subtract the difference.
For example: You are in zone C (-3) and your longitude is 45° E. Zone time is 1430 C. What is the GMT?
When converting from GMT to either LMT or Zone time, the opposite of the above applies.