Muhammad Shahid Qureshi, Nasiruddin Khan.
A comparative study of arithmetic, observational and predicted lunar calendar for Pakistan for years 2000-2004.
J Basic Applied Sci Jan ;2(2):91-103.

Arithmetic Lunar Calendar is based on the concept of Leap Years and the average motion of the Moon. However, the actual motion of the Moon varies greatly due to various factors which cause the observational calendar to be different from the arithmetic calendar. Whereas, the Calendars based on prediction criterion of Yallop are the closest to the observational calendar. In this work, we compare these calendars with the actual observational calendar in practice in Pakistan for the years 2000 to 2004. It is found that on average 95% observations are according to the Yallop’s criterion. The disagreement is the result of either the bad weather due to which the new Lunar crescent could not be sighted and the Lunar month began one day late, or too optimistic claims of observation and the Lunar month began one day earlier than predicted. On the other hand the disagreement between the Arithmetic Calendar and the observational one is 54%.

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