The method of determining the Hijri calendar at Al-Falah Islamic Boarding School Kediri: An astronomical and phenomenological analysis

This study examines the distinctive approach to determining the Hijri calendar (particularly for Ramadan, Shawwal, and Dhu al-Hijjah) practiced by Al-Falah Ploso Kediri Islamic Boarding School, which frequently differs from both government rulings and Nahdlatul Ulama's positions. Employing empirical research methods through structured interviews with key informants, the investigation pursues two primary objectives: first, to analyze the methodological framework employed by Al-Falah in establishing the Hijri calendar; and second, to evaluate this practice through astronomical and phenomenological lenses. The findings reveal that while Al-Falah utilizes multiple calculation methods, its primary reference is the Sullam al-Nayyiroin system, employing a lunar altitude criterion of 2 degrees. Astronomically, this approach falls under the category of hisāb taqrībi (approximate calculation), which demonstrates limited accuracy in light of contemporary astronomical advancements. Phenomenologically, the boarding school's adherence to this traditional method serves to preserve the institutional sanad (chain of transmission) established by its founders, maintaining both scholarly continuity and practical application. This practice holds particular significance for the school's students, alumni, and affiliated communities, while other segments of the population follow government determinations due to limited understanding of the technical considerations. The study highlights the complex interplay between traditional Islamic scholarship, astronomical precision, and community dynamics in contemporary Hijri calendar determination, offering insights into the ongoing discourse surrounding Islamic timekeeping methodologies.