True Dawn: the defi nition by the Sharia and the terminology of astronomers

2021 ◽  
Vol 14 (3) ◽  
pp. 625-644
Author(s):  
M. Z. Maghomedov
Keyword(s):  
Visual Observation ◽  
Arab Countries ◽  
The Sun ◽  
Exact Time ◽  
Mathematical Calculation ◽  
The Republic ◽  
Morning Prayer

The object of the research is the problem of determining the exact time of the True Dawn onset (al-fajr as-sadik), with which the rituals of fasting and praying begin in Islam, as well as the completion of the rite of standing (wukuf) on Mount Arafat during the Great Pilgrimage (hajj), and its diff erence from the so-called “False” Dawn. (al-fajr al-kazib).  The paper presents the Hadiths describing the signs of these two astronomical phenomena and reveals the results of visual observation of the onset of the True Dawn’s exact time in a number of Arab countries and in the Republic of Dagestan according to the mathematical calculation of the angle of the Sun inclination and the degree of the Sun position (azimuth) towards the horizon of the observed terrain during the true dawn.  The study was based on the determination of the onset of the morning prayer exact time according to the methodology of mathematical calculations by astronomers of the early and late periods, and of the authoritative Muslim jurists (faqihs) as well.

scholarly journals PENENTUAN AWAL WAKTU SUBUH MENGGUNAKAN SKY QUALITY METER PADA VARIASI DEKLINASI MATAHARI

2019 ◽  
Vol 3 ◽  
pp. 184 ◽  
Author(s):  
Mustofa Ahyar ◽  
Yudhiakto Pramudya ◽  
Abu Yazid Raisal ◽  
Okimustava Okimustava
Keyword(s):  
Experimental Method ◽  
Research Method ◽  
Negative Sign ◽  
Positive Sign ◽  
The Sun ◽  
Brightness Level ◽  
Celestial Equator ◽  
Sky Brightness ◽  
Morning Prayer

<p class="AbstractEnglish"><strong>Abstract:</strong> 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.</p><p class="KeywordsEngish"><strong>Abstrak:</strong> 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 <em>Sky Quality Meter (SQM)</em>. Terdapat selisih awal waktu salat subuh antara perhitungan <em>Software Accurate Times</em> 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.</p>

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

HADIS KURAIB DALAM KONSEP RUKYATUL HILAL

1970 ◽  
Vol 13 (2) ◽  
Author(s):  
Muslih Husein
Keyword(s):  
The West ◽  
The Earth ◽  
New Moon ◽  
The Republic

Hisab dan rukyat, hakikatnya, adalah cara untuk mengetahui pergantian bulan. Kajian ini memperlihatkan beberapa temuan. Pertama, korelasi antara hadis Kuraib dan terjadinya perbedaan penetapan awal Ramadan, Syawal, dan Dzul Hijjah di Indonesia. Kementerian Agama Republik Indonesia telah menetapkan bahwa Indonesia secara keseluruhan menjadi satu wilayah hukum (wilayatul hukmi). Kedua, tentang keberhasilan rukyat al-hilal di satu kawasan yang diberlakukan bagi kawasan lain di muka bumi. Perlu diketahui bersama bahwa visibilitas pertama hilal tidak meliputi seluruh muka bumi pada hari yang sama, melainkan membelahnya menjadi dua bagian: (1) bagian sebelah Barat yang dapat melihat hilal dan (2) bagian sebelah Timur yang tidak dapat melihat hilal.Hisab and rukyat is a way to know the turn of the month. This study shows several findings. First is the correlation between Kuraib traditions and differences in the determination of the beginning of Ramadan, Shawwal, and Dhul-Hijjah in Indonesia. Ministry of Religious Affairs of the Republic of Indonesia has stated that Indonesia as a whole into a single jurisdiction (wilayatul hukmi). Second, on the success rukyat alhilal in one area that applied to other regions of earth. Important to know that the first visibility of the new moon does not cover the entire face of the earth on the same day, but splitting it into two parts: (1) part of the West to see the new moon, and (2) part of the East were not able to see the new moon.

scholarly journals Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

2017 ◽  
Vol 12 (S330) ◽  
pp. 148-151 ◽  
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Sun ◽  
Thick Disc ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

scholarly journals Solar structure and evolution

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Solar Surface ◽  
Solar Neutrinos ◽  
Solar Interior ◽  
Stellar Structure ◽  
The Sun ◽  
Physical Processes ◽  
Solar Evolution ◽  
Internal Properties ◽  
Atmospheric Phenomena

AbstractThe Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

Determination of integral indicators characterizing the possibility of accommodating the evacuated population in the territory of the Republic of Kazakhstan

2020 ◽  
pp. 154851292097028
Author(s):  
Yernar Zh Akimbayev ◽  
Zhumabek Kh Akhmetov ◽  
Murat S Kuanyshbaev ◽  
Arman T Abdykalykov ◽  
Rashid V Ibrayev
Keyword(s):  
Statistical Data ◽  
Armed Conflicts ◽  
Security Issues ◽  
Inaccurate Information ◽  
The Subject ◽  
The Republic ◽  
The Impact ◽  
Integrated Indicators ◽  
Selection Of

Studying the historical facts of past wars and armed conflicts and natural and man-made emergencies, today in the Republic of Kazakhstan one of the most important security issues is the preparation and organization of the evacuation of the population from possible dangerous zones, taking into account the emergence of new threats to the country’s security. The paper presents an algorithm for constructing universal scales of the distribution function of opportunities by types of support and rebuilding them into subject scales using display functions. The purpose of the paper is to determine the integral indicators characterizing the possibility of accommodation of the evacuated population and the impact on resources during relocation. On the subject scales of cities and districts of the region, indicators of the possibility of relocation of a certain amount of the evacuated population by types of support and indicators characterizing the impact on the district’s resources during resettlement of a certain amount of the evacuated population are determined. It was concluded that the use of integrated indicators allows the selection of areas to accommodate the evacuated population without the use of statistical data, in conditions of incomplete and inaccurate information. The presented method does not replace traditional methods based on classical methods of territory assessment by the level of life sustenance, but also allows their reasonable combination with the experience of specialists in this field, taking into account the incompleteness, uncertainty, and inconsistency of the initial data of the study area, which does not allow the application of existing methods.

scholarly journals Lithium Observations in the Sun

1968 ◽  
Vol 1 ◽  
pp. 243-246
Author(s):  
Edith A. Müller
Keyword(s):  
Unknown Origin ◽  
Absorption Feature ◽  
The Sun ◽  
Degree Of Ionization ◽  
Lithium Abundance ◽  
Resonance Doublet ◽  
Lower Temperature ◽  
Central Depth ◽  
The Continuum

The determination of the lithium abundance in the solar atmosphere is essentially based on the LiI resonance doublet at λ 6707·761 and 6707·912 Å. These two lines form a very faint absorption feature, the central depth of the stronger component being of the order of 1% of the continuum. The violet component, which is also the stronger of the two, occurs near the red wing of a faint solar line of unknown origin, and the lines appear to be blended with other faint lines including possibly the doublet of the Li6 isotope (the isotopic shift being 0·160 Å). No other line of LiI has been detected in the Fraunhofer spectum of the undisturbed solar disk. This is nothing surprising, because practically all lithium is expected to be ionized in the photosphere on account of its low ionization potential (Xion = 5·37 e.v.). In sunspot spectra the lower temperature reduces the degree of ionization of lithium and causes a strengthening of the LiI lines. In fact, the LiI resonance lines which appear as a very faint absorption feature on disk spectra are about 50 times stronger in spot spectra. Furthermore, the very weak feature at λ 6103·6 Å was identified by Dubov (1964) and by Schmahl and Schröter (1965) as due to the 2s 2S–3d 2D transition of LiI. Both the resonance doublet and the faint feature at 6103·6 Å have been used by the above-mentioned authors to derive the lithium abundance in spots.

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