<![CDATA[Abstract: Determination of the beginning of the prayer time is very important for Muslims because it is one of the prayer pillars. However, the determination of beginning morning prayer is still difficult, because the sun is below the horizon. The determination of the beginning of dzuhur, ashr, and maghrib times are easier since the sun's shadow is still clearly visible. The sun position is determined by sun declination. The sun declination value is given a positive sign (+) when it is north of the sky equator and negative sign (-) when it is to the south of the celestial equator. This research method uses the experimental method. The determination of the subuh time has been done by measuring sky brightness level that was measured by SQM. There is a difference between the beginning of morning prayer time between the Accurate Times software calculation and the measurement. In the sun declination variation, difference data ranged from 21 - 36 minutes. From this study, it was concluded that the value of sun declination affected the beginning of dawn time.Abstrak: Penentuan awal waktu salat yang tepat penting bagi umat muslim, karena merupakan salah satu rukun salat. Namun, penentuan awal waktu salat subuh masih sulit, karena matahari berada di bawah horizon. Penentuan awal waktu zuhur, asar, dan magrib lebih mudah karena bayangan matahari masih terlihat jelas. Posisi matahari ditentukan oleh deklinasi matahari, nilai deklinasi matahari diberi tanda positif (+) ketika berada di sebelah utara ekuator langit dan negatif (-) ketika berada di sebelah selatan ekuator langit. Metode penelitian ini menggunakan metode eksperimen. Penentuan awal waktu subuh dengan menggunakan pengukuran Tingkat Kecerahan Langit (TKL) ini diukur dengan Sky Quality Meter (SQM). Terdapat selisih awal waktu salat subuh antara perhitungan Software Accurate Times dan pengukuran. Pada variasi deklinasi matahari diperoleh data selisih berkisar antara 21-36 menit. Dari penelitian ini disimpulkan bahwa nilai deklinasi matahari berpengaruh terhadap awal waktu subuh.]]>
