- Although days start at midnight in the Gregorian Calendar, other calendars can use different times to start their days. Start times often relate to dawn, mid-day, dusk or mid-night
- Some calendars have leap-days (e.g. Gregorian Calendar day 29th February,) whilst others have leap-months (e.g. Adur I in Hebrew Calendar.)
- Month numbers are usually expressed as the number of months (starting at 1) since the first day of that calendars year. This means that during a leap year, in a calendar with leap months, every month number on/after the leap month will have a month number "one more" than the same month name in a normal year.
- Non-Gregorian Calendar years are unlikely to start on 1st January of the Gregorian year. Lunar Cycles "drift" in relation to solar calandars, hence, the Gregorian date associated with the first day of a lunar calendar year will change annually.
- Some (but not all) of the Lunar calendars use a physical sighting of the new moon to confirm the start of some/all their months. Whilst you can use maths to calculate teh approximate date a new moon will be visible, it is currently impossible to predict the precise date of these sightings. This makes it impossible to precisely convert future dates until the relevant sighting is confirmed.
- Some calendars use a simple count of days (or hours, minutes, seconds etc.) since an specific event (known as an epoch.) e.g.Unix Timestamp = seconds since midnight on Gregorian day 1st Jan 1970. The start date for an Epoch basec calendar can be either Day 1 or Day 0, depending on the calendar.
Convert Gregorian to Standard CalendarThe Gregorian Calendar is used by the UK, North America and Europe. VB.Net has built in functions to convert Gregorian calendars into several other world calendars. This function deonatrates one methed of using these ready-made calendar conversions.
Convert Gregorian to Epoch Calendar
Convert Epoch Calendar to Gregorian
Julian and Modified Julian
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