Relevansi penggunaan umur bulan sebagai syarat alternatif dalam kriteria imkanur rukyah

The Imkanur rukyah criteria can be defined as the minimum limits for expecting the new moon’s visibility to determine the beginning of Hijri months. It has been used in Hijri calendar development of Malaysia since 1992. According to the criteria, the new moon is considered visible if the altitude at sunset is at least 2o and elongation between moon and sun is at least 3o, or at moonset, the age of the moon is at least 8 hours. The altitude limit of 2o and elongation limit of 3o indeed was determined according to the observation data of new moon visibility made in Indonesia, whereas there is no clear written source of 8 hours moon’s age. The use of moon’s age criterion as an alternative to geometry criteria can lead to confusion if both conditions give different results. Therefore, this study was performed to assess the relevance of using moon’s age as an alternative in Imkanur rukyah criteria used in Malaysia. The study utilize the data of sun and moon’s positions, time of sunset, time of moonset and also time of conjunction (new moon). These data are calculated by developing a program named i-Hijri. Based on the analysis for determining Hijri dates from 1996 to 2015, there are 22 discrepancies found between the moon’s age and geometry criteria, in which 5 of them occur for the month of Ramadan, Syawal and Zulhijjah. This condition shows that moon’s age criterion is not always consistent to geometric criteria. Therefore, the use of moon’s age as an alternative criterion for determining the beginning of Hijri month is considered irrelevant and should be reviewed