Red-to-White Transition of Dusk Horizon

This paper attempts to uncover the background theory of twilight. It has a direct association with Islamic prayer times i.e. c Ishā" and Ṣubḥ whereby shafaq (afterglow or remnant of sunset at certain degree) and fajr (first light before sunrise) both are astronomical phenomena part of twilight stage respectively. The recital of prayer times or ṣalāt within its time set by Islamic law code should be a main solicitude for all Muslims. The definitions of the times of prayer were outlined in al-Qur'ān and al-Ḥadīth (prophetic statement). Those outlined prayer times were interpreted by fiqh (Islamic jurisprudence) which has numbers of school of thought (madhhāb), consequently it affect the parameter on establishing the beginnings and the endings of c Ishā" and Ṣubḥ. The set parameter is then understands by delving background of twilight scientifically.

2018

The indication of began to enter the shubuh prayer time is when emerge the morning dawn and lasted until the sun rises. The sun position when emerge the morning dawn is below the intrinsic horizon marked with a minus sign (-) with the value of a certain height. The Ministry of Religious Affairs has set the sun altitudes of dawn in the shubuh prayer time with minus (-) 19° + sunrise/sunset altitudes as standard is the reference time of dawn prayers in Indonesia. However, this provision in fact reap discourse in some quarters because it is not in accordance with the phenomenon of morning dawn emergence at the beginning of the shubuh prayer time empirically. This study aims to decide the morning dawn, as the beginning of dawn determinant. The tool used in this study is the Sky Quality Meter (SQM), to detecting the morning dawn emergence as a sign of the beginning of the shubuh prayer time. The results of this study found that the brightness of the sky throughout

2020

The Subh time specified in the prayer schedule has been considered as early as 20 to 30 minutes, whereas prayer must be done on time. This study aims to verify the phenomenon of dawn shadiq (astronomical twilight) as a mark of dawn time. The research was carried out by observation method using Sky Quality Meter technology and the results will be analyzed with the approach of ushul fiqh science, astronomy, and mathematics. The approach to the science of ushul fiqh is to analyze the normative aspects, the approach of astronomy is to analyze the phenomenon of dawn, and the approach of mathematics to analyze the results of dawn observations with Sky Quality Meter. The results of the study showed that at dawn Shadiq can be observed factually at a depression angle of 15 ° to 18 ° below the equivalent horizon of 60 to 72 minutes before sunrise. The magnitude of the depression angle is different from the determination of the Ministry of Religion of the Republic of Indonesia and Islamic Organizations that is equal to 20 ° below the horizon equivalent to 80 minutes before sunrise. The implication of the findings of this study is the shift of dawn time, imsak time and the start time of fasting 8 to 20 minutes from the time specified in the prayer time schedule.

Studia Geophysica Et Geodaetica, 1964

Indonesian Review of Physics, 2021

Measuring the brightness of the night sky and determining the start of Fajr prayer times can be done using SQM. Observations were made at OIF UMSU with coordinates 3o 34' 55.06" N and 98o 43' 17.09" E. The sky brightness was measured using three SQMs mounted facing the zenith, eastern horizon, and western horizon. The night sky brightness values for SQM directed to the zenith, eastern horizon, and western horizon are 18.23 mpsas, 15.82 mpsas, and 15.47 mpsas. The beginning of fajr prayer time produced by SQM is after the beginning of fajr prayer time obtained using the Accurate Times concerning the Sun's altitude 18o below the horizon. The difference obtained by SQM directed to the zenith, eastern horizon, and western horizon is 29.5 minutes, 36.7 minutes, and 39.5 minutes. In other words, the beginning of Fajr prayer time used in Indonesia is earlier than it should be.

NRIAG Journal of Astronomy and Geophysics, 2014

Twilight observations were carried out in the period between 1984 and 1987 in different seasons at different sites of Egypt (Baharia, Matrouh, Kottamia and Aswan) through a cooperation project between Dar El-Iftaa' and the Egyptian Academy of Scientific Research and Technology. Naked eye observations of the first light of the dawn were done in parallel to the photoelectric measurements of the twilight phenomena. The depression of the sun below the horizon corresponding to the first light was calculated from the time of observations. Our estimates show that the normal eye can just discriminate the dawn (the first white light thread) at a depression of 14.7°with a maximum value of 15.08°and a minimum value of 12.01°. This result agrees with result obtained by our previous photoelectric measurements.

International Journal of Sustainable Lighting

Muslims has differentiated between new moon and Islamic new moon (hilal). The determination of first day of months based on visibility of Islamic new moon (hilal) i.e. sightings of the first sliver of the waxing moon marking the start of each month. One major issue that has affected hilal visibility for many years is misdirected, excessive and obtrusive artificial light. The objective of this research is to study the impact of light pollution on the visibility of hilal. The data were taken using Sky Quality Meter (SQM) which records the visual magnitudes per square arcsecond (mpsas) to measure sky limiting magnitude. Result showed that reading between 16-22 mpsas, the chances to witness hilal is high. Any lower than 16mpsas, the hilal is not visible. The main result of this research is to find out a vital parameter of hilal observations which leads to propose a new criterion i.e. sky limiting magnitude.

NRIAG Journal of Astronomy and Geophysics, 2016

Results of unaided eye observations of the morning twilight phenomenon at Tubruq of Libya are recorded. These results are an average of 623 observing twilights carried out at Tubruq ( = 32° 05´ N, = 23°5 9´ E) for the desert background in the time interval (2010)(2011)(2012)(2013). The average enabled us to get an average depression of the sun below the horizon of about 13.144° which lies in a range between (11.13° Do 14.7°). The results show that there is about 4° difference between our obtained value and that currently used in Libya which is 18.25°. The azimuthally range of observation in the solar vertical direction ranges from 0° to 10°, while the phenomenon was followed from 0° to 20° along the altitudinal range. The results indicate that the dawn (first light) occurs according to normal eye estimates at Tubruq at sun vertical depression angle D = 14.7°.

In this paper, the determination of Islamic prayer time using scientific method has been extensively investigated. We focused on optical sky brightness at dusk from May 2007 through April 2008 intermittently. The measurements of twilight sky brightness were covered at two (2) different sites covering East and West coast of Peninsular Malaysia. Based on Islamic law code's requirement, the measurements were done using human eye and electronic device (Sky Quality Meter) as the detectors which is Sunnah (qualitative) and scientific (quantitative) approaches respectively. Results showed that there are clear indications of changes of the receipt of light when Sun at certain degree below horizon that manifest itself by plateau form in twilight sky brightness dependences versus solar zenith angle. Interestingly, statistical analysis is also showed 1-2 minutes of differences compare with theoretical calculation of each data. It is also clarified that the yearly averages of solar depression by observation are best correlated within the range of 17.3 o -19.5 o for Isha'.

Results of unaided eye observations of the morning twilight phenomenon at Tubruq of Libya are recorded. These results are an average of 623 observing twilights carried out at Tubruq (= 32° 05´N, = 23° 59É) for the desert background in the time interval (2010-2013). The average enabled us to get an average depression of the sun below the horizon of about 13.144° which lies in a range between (11.13° Do 14.7°). The results show that there is about 4° difference between our obtained value and that currently used in Libya which is 18.25°. The azimuthally range of observation in the solar vertical direction ranges from 0° to 10°, while the phenomenon was followed from 0° to 20° along the altitudinal range. The results indicate that the dawn (first light) occurs according to normal eye estimates at Tubruq at sun vertical depression angle D = 14.7°. o