Naked eye determination of the dawn for Sinai and Assiut of Egypt

Hassan, A.H.; Issa, Islam; Mousa, Mohammed Saleh; Abdel-Hadi, Yasser A.

doi:10.1016/j.nrjag.2016.02.001

Cited by 5 publications

(2 citation statements)

References 12 publications

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“…The results of D o agree with a study done by Dani (2016) which used photoelectric techniques in Yogyakarta, Indonesia (The result of D o by Dani was -17°). The D o values differ from the observations using the naked eye technique in a study done by Hassan et al (2016) at Sinai, Egypt. The result at Sinai for D o was -14.61° which is higher than this study.…”

Section: Resultscontrasting

confidence: 95%

Measuring the Sun Depression Angle of Dawn with a DSLR Camera

Bahali¹,

Samian²,

Muslim³

et al. 2018

JSM

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The first visibility of the dawn occurs at a definite angle of the sun depression, D o which is used to calculate the fajr (dawn) prayer time. Dawn observations were carried out using Digital Single-lens Reflex (DSLR) camera in the period from February to December 2017 at several locations in both Malaysia and Indonesia (Lat. between 2.0°-7.0° N, Long. 95.0°-106.0°E). Within the observational period, 64 days of the dawn luminance at horizon were recorded with backgrounds of both sea and land. The purpose of these observations was to determine the sun depression angle D o at the first moment when the dawn is seen using a DSLR camera. The results indicated that D o can be determined using a DSLR camera. The value of D o is between-14.5° and-18.5° with a mean value of-16.67° and standard deviation of 0.9992. This suggests that the new sun depression angle D o for dawn prayer is-17.0°.

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Section: Resultscontrasting

confidence: 95%

Measuring the Sun Depression Angle of Dawn with a DSLR Camera

Bahali¹,

Samian²,

Muslim³

et al. 2018

JSM

View full text Add to dashboard Cite

show abstract

“…In addition to the observations of several different sites deep in the desert (see Table 3). To convert the local time of true dawn (B.T N ) to Sun vertical depressions, D o , the equations of Hassan et al (2009Hassan et al ( , 2016, were used and the results were checked by Moon calculator 6.0 (Monzur Ahmed, http:// www.starlight.demon.co.uk/mooncalc). The depth of the desert means that these places are far from civil activity with their airborne pollutants, light pollutants or any human activity.…”

Section: Methodology and Sit Observationsmentioning

confidence: 99%

Twilight observation by the naked eye of the dawn sincere at Hail and other areas in Saudi Arabia

Khalifa

Hassan

Taha

2018

NRIAG Journal of Astronomy and Geophysics

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Naked eye observations of morning twilight phenomenon at Hail and other areas of Saudi Arabia are recorded. During the interval from 2014 to 2015, about 80 morning twilight observations were carried out in Hail at longitude λ = 41°42′E and latitude φ = 27°31′N for a desert background. The phenomena was followed over azimuth angles ranged from 0°to 20°of solar vertical direction and from 0°to 10°along the altitudinal range. By selecting 32 days with a very good visibility, it was found that Sun depression, D o , lies in a range between 13.48°a nd 14.69°with an average of 14.014°± 0.317. The difference between our obtained value and that one which is currently applicable in Saudi Arabia is about 4°. The results indicate that dawn (white thread browser) occurs at a sun vertical depression angle D o = 14.66°(mean + 2SD) according to the normal eye estimations. The results at different areas in the deep desert in KSA showed that the beginning of morning twilight and true dawn is at sun vertical depression D o = 14.88°(mean + 1SD). The current study shows significant results, which are comparable with both naked eye observations and photoelectric measurements of true dawn in both Egypt and Libya for desert background.

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Pseudo dawn and true dawn observations by naked eye in Egypt

Semeida

Hassan

2018

Beni-Suef University Journal of Basic and Applied Sciences

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Naked eye determination of the dawn for Sinai and Assiut of Egypt

Cited by 5 publications

References 12 publications

Measuring the Sun Depression Angle of Dawn with a DSLR Camera

Measuring the Sun Depression Angle of Dawn with a DSLR Camera

Twilight observation by the naked eye of the dawn sincere at Hail and other areas in Saudi Arabia

Pseudo dawn and true dawn observations by naked eye in Egypt

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