Determining the beginning of Islamic lunar month is the most important thing, because it relates to celebrate the various festivals in Islam. Multiculturalism those happen in Indonesia are also happened in method to determine the beginning of Islamic lunar month. They are Naqsabandiyah and Syattariyah Congregations in West Sumatera. Although they use same almanac and starts counting from Thursday, they have different result and have their own characteristic.
This study purposes to compare the method used by these congregations and finding the advantages and disadvantages. The study included qualitative research and also type of field research. Primary data of this research was taken from hand writing note of both congregations and interviewing some people who are involved directly with this activity observed. Secondary data of this research are books, journal, and official archive. Analysis data method used interactive data analysis to research the methods used by and comparative to compare the result.
This research found that both of congregations use same almanac but they differ in counting their first letter based on their almanac. Naqsabandiyah starts counting from second dal while Syattariyah starts counting from ha of year letters. In case of rukyah (sighting crescent), they use naked eyes and data input of their almanac is formed of alphabet and numeral revolution from time to time. Then advantages of Naqsabandiyah are their calculating is more accurate while the disadvantages is their rukyah place is unrecommended. The advantages of Syattariyah is recommended place of rukyah while disadvantages is their calculating is lower 2 untul 3. Both of them has very simple calculation method.