<![CDATA[Abstrak: Permasalahan penentuan awal bulan kamariah di Indonesia kerap menimbulkan perbedaan di antara organisasi masyarakat (ormas) Islam akibat tidak adanya keseragaman dalam kriteria visibilitas hilal. Untuk menjembatani hal tersebut, kriteria imkanur rukyat MABIMS diharapkan menjadi solusi yang menyatukan pendekatan hisab dan rukyat. Namun, kriteria awal MABIMS (2-3-8) dinilai terlalu rendah dan sulit diaplikasikan secara empirik di wilayah tropis. Oleh karena itu, disepakati kriteria baru MABIMS (IR 3-6,4), yakni tinggi hilal minimal 3 derajat dan sudut elongasi 6,4 derajat. Meski demikian, masih terdapat perdebatan mengenai keakuratannya. Penelitian ini menganalisis usulan batas bawah visibilitas hilal berbasis parameter fisis pada saat kontras maksimum, yang lebih sesuai dengan kondisi tropis Indonesia. Ditemukan bahwa pada saat kontras maksimum (sekitar 25–30 menit setelah matahari terbenam), hilal memiliki ketinggian rata-rata 2° dan elongasi 13°, yang bila ditarik ke waktu ghurub setara dengan ketinggian 5°. Hal ini menunjukkan bahwa hilal sulit terlihat pada ketinggian di bawah 3° tanpa alat bantu. Oleh karena itu, usulan parameter visibilitas hilal ini layak dipertimbangkan sebagai koreksi terhadap kriteria MABIMS di wilayah tropis.Kata kunci: Visibilitas hilal, MABIMS, kontras, wilayah tropis, imkanur rukyat. Abstract: The problem of determining the beginning of the month of Ramadan in Indonesia often causes differences among Islamic community organizations (CSOs) due to the lack of uniformity in the criteria for the visibility of the new moon. To bridge this, the criteria for imkanur rukyat MABIMS are expected to be a solution that unites the hisab and rukyat approaches. However, the initial criteria of MABIMS (2-3-8) were considered too low and difficult to apply empirically in the tropics. Therefore, it was agreed that the new criteria for MABIMS (IR 3-6.4), namely the height of the hilal is at least 3 degrees and the elongation angle is 6.4 degrees. However, there is still debate about its accuracy. This study analyzes the proposed lower limit of hilal visibility based on physical parameters at the time of maximum contrast, which is more in line with Indonesia's tropical conditions. It was found that at the time of maximum contrast (about 25–30 minutes after sunset), the hilal had an average height of 2° and an elongation of 13°, which, when pulled to the ghurub time, was equivalent to a height of 5°. This shows that the hilal is difficult to see at an altitude below 3° without aids. Therefore, this proposed hilal visibility parameter is worthy of consideration as a correction to the MABIMS criteria in the tropics.Keywords: Visibility of the hilal, MABIMS, contrast, tropical regions, imkanur rukyat. ]]>
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