Contemporary Haqiqī Calculation: Analysis of Rinto Anugraha's Lunar Eclipse Calculation Methods

Abstract

Classical Islamic astronomy literature that discusses eclipse calculations still uses the ḥaqiqī bi al-taqrīb method with low accuracy. In its development, Islamic astronomical literature studies the calculation of lunar eclipses with high accuracy, including Mekanika Benda Langit work by Rinto Anugraha. This article aims to analyze the calculation method and accuracy of the Rinto Anugraha lunar eclipse and compare it with Jean Meeus, Bao Lin Liu, and Alan D. Fiala's calculations NASA (National Aeronautics and Space Administration). Using bibliographic research and descriptive-comparative methods, the author finds that the method of calculating the lunar eclipse of Rinto Anugraha is contemporary haqiqī. The calculation of the lunar eclipse proposed by Rinto Anugraha is based on Jean Meeus' lunar eclipse calculation, and slight modifications are using NASA data. Rinto Anugraha's lunar eclipse calculation has a high level of accuracy because it has the most significant average difference of 3 minutes 36 seconds in the penumbral eclipse begins stage with the results of the lunar eclipse calculations from Jean Meeus, Bao Lin Liu and Alan D. Fiala, and NASA. Anugraha's contemporary calculation method has implications for simplifying the lunar eclipse calculation formula and the range of lunar eclipses that can be calculated further.