Towards the Compilation of the Global Twilight Pattern
DOI:
https://doi.org/10.33102/uij.vol33no1.269Keywords:
global twilight pattern, sun depression angle, sky brightness, polynomial regression model, image processing and analysisAbstract
This paper summarizes ISRN’s 3-years research on the occurrence of dawn and dusk to mark the timings of the Fajr and Isha prayers. We acquired the astronomical data not only in Indonesia but also in Malaysia, the US, Egypt, and Turkey. It will be an attempt to compile a global twilight pattern in the future. The main instrument used is a Sky Quality Meter (SQM) that records the sky brightness data. For quality assurance, ISRN-UHAMKA employed dozens of imaging sensors ranging from an All Sky Camera, different types of DSLR, and gadget cameras. From hundreds of astronomical data, we have collected; it seems that the occurrence of the real twilight to mark the Fajr prayer throughout the world is the same. That is when the sun is at its depression angle of around 120-130. Likewise, the dusk to mark the end of the Maghrib prayer also occurs when the sun is at a solar depression angle around 120-130. Meanwhile, Muslims in the world use different solar depression angles ranging from -150 to -200.fields.
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Copyright (c) 2021 Harry Ramza, Zamah Sari, Bunyamin Bunyamin, Tono Saksono, Mohd Haris Md Khir
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