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The first visibility of the lunar crescent

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Abstract

The problem of predicting the moment when, after conjunction, the new crescent will become visible is both astronomical and physical. Although realized already by Ptolemy, the actual solution never did go much beyond the well-established Babylonian rule of thumb that the moon cannot be seen earlier than one day after conjunction.This paper first discusses the importance of the sighting to the peoples of Islam and then mentions the criteria which control the phenomenon. This is followed by an outline of the theoretical solution given by the early Arab astronomers. It then proceeds to give a more accurate treatment, according to modern methods, which leads to rules by which the appearance and disappearance of the crescent can be predicted to within five minutes of time.The second part of the paper presents translated extracts on the subject from the oldest sources, using modern astronomical nomenclature. These are taken from the Hindu compendia Surya Siddhanta and Pancha Siddhantika, and from al-Battani's Handbook of Astronomy.

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... Another criterion, used by Tabarı -, states that the new lunar crescent will not be seen if the Sun depression is less than 9°·5 at moonset 5 . These two criteria are based on one variable, but Al-Battanıused several variables 6 because, when using one condition, the crescent will not be sighted according to one arc but to many arcs. Al-Battanıincluded the azimuth of the Moon relative to the Sun, the Earth-Moon distance, and the width of the lunar crescent as conditions for thin-lunar-crescent visibility. ...
... The Maunder criterion is similar to the socalled Indian criterion, published in the Indian Astronomical Ephemeris 9 . In 1977, Bruin published a new approach addressing the earliest-lunar-crescent visibility 6 , using new observations on factors such as lunar-crescent width (W ), solar depression, and the necessary contrast for naked-eye observations of the lunar crescent. The criterion adopted a minimum lunar-crescent width (W = 0 ·5), which represents the limit of lunar-crescent visibility 6 . ...
... In 1977, Bruin published a new approach addressing the earliest-lunar-crescent visibility 6 , using new observations on factors such as lunar-crescent width (W ), solar depression, and the necessary contrast for naked-eye observations of the lunar crescent. The criterion adopted a minimum lunar-crescent width (W = 0 ·5), which represents the limit of lunar-crescent visibility 6 . In 1981, Ilyas estimated that Bruin's visibility threshold was an overestimate, and calculated the minimum lunar width as W = 0 ·25, subsequently determining a new approach based on dividing (ARCV-DAZ) curve, which shows good agreement with Maunder's criterion 10 . ...
Article
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Predicting the visibility of thin lunar-crescents following the new moon is diffcult and challenging for several technical reasons. The visibility of the earliest new moon has long been used to determine the lunar-crescent calendar and is still used today. Many criteria exist for the frst visibility of the lunar crescent. Here, we test the most-commonly-used criteria for thin-lunar-crescent visibility. We used 545 observations, including both positive and negative sightings, made by professional and highly-trained astronomers over a duration of 27 years (1988 – 2015) and from different locations at latitudes between 20° N and 29° N (within Saudi Arabia). We developed a new criterion for lunar-crescent visibility using lunar-crescent width (W arc of vision (ARCV). This new model can be used to predict the visibility of the lunar crescent by naked eye or aided eye, which is fundamental for the lunar-crescent calendar followed by several cultures and religions. ) and the
... Observation and the visibility of very young lunar crescent near the Sun at western horizon after sunset are indispensable important factor in determining important religious Islamic calendar (Bruin 1977;Schaefer 1993;Dogget, Schaefer 1994;Hoffman 2003; Taufiq et al. 2010). However, in an advanced scientific and technological based, the observation of lunar crescent near the Sun can be undertaken in broad daylight. ...
... The Muslim year as a lunar based calendar contains twelve lunar months, each starting at least one day after the new moon, at sunset of the evening of the first sighting of the lunar crescent. While the mean lunar month (the synodic month) has 29.53 mean solar days, then if there are no clouds, the new crescent can always be seen 29 or 30 days after the previous one (a comple te month), but in almost half of the cases, it is seen already on the 29 th day (an incomplete month) (Bruin 1977). Observation of lunar crescent near the sun at western horizon after sunset is indispensable important factor in determining important religious dates Proceedings of the Third International Conference on Mathematics and Natural Sciences (ICMNS 2010) (Dogget, Schaefer 1994). ...
... The length of baffle depends on the objective or aperture diameter and angle of incoming light. The simple formula is tan (alpha) = aperture diameter / length of baffle (1) So if the aperture diameter is 102 mm and the angle of incoming light is 5 degree, then length of baffle will be 116 cm. We have made a 150 cm long baffle and incoming light angle in about 4 degree. ...
Article
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Observation and the visibility of very young lunar crescent near the Sun at western horizon after sunset are indispensable important factor in determining important religious Islamic calendar (Bruin 1977; Schaefer 1993; Dogget, Schaefer 1994; Hoffman 2003; Taufiq et al. 2010). However, in an advanced scientific and technological based, the observation of lunar crescent near the Sun can be undertaken in broad daylight. The project will develop some additional observing tools and image acquisition/processing procedures that one enable to observe the very young crescent in broad daylight to prove that one can see it at horizon after the sunset as this is the less stringent condition. The main problem is how to minimize the atmospheric and instrumental stray light that can obscure the information from the very young crescent image from the daylight background. We have developed and tested a simple extended telescope baffle that can reduce the incoming stray light from the sky and environment. Hence, it will increase the contrast of the lunar crescent. Some requirements and optimization have been applied for the observing system (telescope and its mounting) and image acquisition/processing procedures. The main constraint was the cloudy sky near and on the first day of lunar calendar in the evening during the first semester of this year. The results will be reported.
... Throughout history, dating back to Babylonian times, the first appearance of the New Moon has been used to determine the calendar. Hindu, Hebrew and Muslim calendars are based on the visual sighting of the first cresent Moon after conjunction with the Sun at the beginning of each month (Bruin 1977). Today, most lunar calendars are based on calculation with a mean lunar synodic period of 29.35 solar days. ...
... Diagram of the telescope detection system as implemented for the New Moon observations. (Bruin 1977;Ilyas 1994;Yallop 1997;Hoffman 2003). ...
... The time of New Moon is defined as the time of minimum elongation of the Moon from the Sun in celestial coordinates (Bruin 1977;Hoffman 2003;Ilyas 1994). for 16 hr 36 min UT and 16 hr 26 min UT respectively. ...
Article
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Sighting and detection of the New Moon at sunset is of importance to communities based on the lunar calendar. This is traditionally undertaken with visual observations. We propose a radio method which allows a higher visibility of the Moon relative to the Sun and consequently gives us the ability to detect the Moon much closer to the Sun than is the case of visual observation. We first compare the relative brightness of the Moon and the Sun over a range of possible frequencies and find the range 5–100 GHz to be suitable. The next consideration is the atmospheric absorption/emission due to water vapour and oxygen as a function of frequency. This is particularly important since the relevant observations are near the horizon. We show that a frequency of ∼10 GHz is optimal for this programme. We have designed and constructed a telescope with a full width at half-maximum resolution of 0$_{.}^{\circ}$6 and low sidelobes to demonstrate the potential of this approach. At the time of the 2012 May 21 New Moon, the Sun/Moon brightness temperature ratio was 72.7 ± 2.2 in agreement with predictions from the literature when combined with the observed sunspot numbers for the day. The Moon would have been readily detectable at ∼2° from the Sun. Our observations at 16 h 36 min ut indicated that the Moon would have been at closest approach to the Sun 16 h 25 min earlier; this was the annular solar eclipse of 00 h 00 min ut on 2012 May 21.
... The work of a number of contributors and authors is reviewed. Yallop's comparison [29] of the Maunder's [13] , the Indian [11] and the Bruin's [3] methods is extended to include a q-test based on third degree polynomial fitted to data using Least Square Approximation. Moreover the possibility of better coefficients in the 2 nd degree curve is considered to be closer to real observations. ...
... A number of 20 th century astronomers have contributed towards the development of a mathematical model for the criterion of earliest visibility conditions on the new lunar crescent. The works of Maunder [13] , Schoch [25] and Bruin [3] are of fundamental importance. These works are mostly based on the observational records of the past two centuries. ...
... In literature, the minimum ARCL reported is 8.5 degrees when the crescent was seen with naked eye. Bruin [3] , considering the importance of Phase considered the observational data about the actual visible width W of the central part of crescent in arc minutes and the ARCV to develop a relation between the two as the criterion for earliest visibility of crescent. The data he used was: ...
Article
Basic techniques of Computational Astronomy are reviewed and presented as the essential tools for simulation of Lunar phenomena. The importance of accurate determination of Julian Date and the Local Sidereal Time is discussed that are essential to determine the local time of sunset and the local coordinates of any object at that time. During the 20th century, a number of authors have contributed towards the understanding of the problem of earliest sighting of crescent Moon. The work of Maunder, Schoch, Bruin and Schaefer has been crucial in the development of this understanding. More recently, the work of Yallop, Ilyas, Ahmed and Shaukat has received great recognition. The work of Ahmed and Shaukat has been based mostly on the Yallop's Criterion. However almost all the modesl are based on the observational data of Schmidt who made observations from Athens for over 20 years during the late 19th century. In this work, a model of q-values developed by Yallop is analyzed in view of Maunders and the Indian Criteria along with the actual semi-diameter of the crescent Moon. The basic criterion is modified on the basis of data more recently collected.
... Some considered the arc length of celestial degrees between the sun and the moon (elongation) at sunset. However, they could not predict the sighting perfectly because they did not consider the local conditions of the horizon at the time of observation, and they omitted the effect of changing the apparent width of the crescent moon and its relation with the brightness of the sky [4]. ...
... In 1977, Bruin [4] modified Fotheringham-Maunder's criterion. He considered the western sky, the moon's surface brightness, and the solar depression (the altitude of the sun below the horizon). ...
Article
Full-text available
Various theories have been proposed since in last century to predict the first sighting of a new crescent moon. None of them uses the concept of machine and deep learning to process, interpret and simulate patterns hidden in databases. Many of these theories use interpolation and extrapolation techniques to identify sighting regions through such data. In this study, a pattern recognizer artificial neural network was trained to distinguish between visibility regions. Essential parameters of crescent moon sighting were collected from moon sight datasets and used to build an intelligent system of pattern recognition to predict the crescent sight conditions. The proposed ANN learned the datasets with an accuracy of more than 72% in comparison to the actual observational results. ANN simulation gives a clear insight into three crescent moon visibility regions: invisible (I), probably visible (P), and certainly visible (V). The proposed ANN is suitable for building lunar calendars, so it was used to build a four-year calendar on the horizon of Baghdad. The built calendar was compared with the official Hijri calendar in Iraq.
... The Moslem year as a lunar based calendar contains twelve lunar months, each starting at least one day after the new moon, at sunset of the evening of the first sighting of the lunar crescent. While the mean lunar month (the synodic month) has 29.53 mean solar days, then if there are no clouds, the new crescent can always be seen 29 or 30 days after the previous one (a complete month), but in almost half of the cases, it is seen already on the 29 th day (an incomplete month) [1]. Observation of lunar crescent near the sun at western horizon after sunset is indispensable important factor in determining important religious dates [2], [5], and [6]. ...
... The length of baffle depends on the objective or aperture diameter and angle of incoming light (alpha). The simple formula is tan (alpha) = aperture diameter / length of baffle (1) So if the aperture diameter is 102 mm and the angle of incoming light is 5 degree, then length of baffle will be 116 cm. For 2 degree angle, the baffle length is about 300 cm. ...
... A visibility criterion has to provide a model for each of these parameters and combine them. For example, the Babylonians (about 2500 years ago) used the time since conjunction as a measure of the Moon's brightness and the lag time (time between Sunset and Moonset) as a measure of the brightness of the sky (Bruin 1977). According to this criterion, the Moon must be at least 24 h after conjunction to be bright enough to E-mail: roy@shum.cc.huji.ac.il see and the lag time must be at least 48 min for the sky to be dark enough for the Moon be seen. ...
... ination of geocentric difference in altitude and semitopocentric crescent width. The use of topocentric measures would be expected to yield more consistent results but little difference is observed. All the above criteria rely on angles between the Sun and the Moon and can all be expressed approximately in terms of altitude and azimuth differences. Bruin (1977) was the first to use photometric arguments to support his lunar visibility criterion based on astronomical angles. Schaefer (1988) was the first to attempt a fully photometric method for predicting visibility of the Moon. He calculated the brightness of the Moon and sky directly and compared the contrast with a known threshold contrast. ...
Article
The first appearance of the new Moon has been used throughout history and is still used today to determine religious calendars.Many methods for predicting the Moon's appearance have been proposed throughout history and new models are still being developed.All these models have to be tested against observations to test their validity.To this end, ancient and modern astronomers have collected observations of new and old crescent Moons.Here we present the results of 539 observations of the Moon made over several years by many experienced observers in good weather conditions.In addition to determining whether or not the Moon was seen, the times of its first and last appearance were also carefully recorded.The addition of the appearance time means that even an easily visible Moon, recorded when it can barely be seen, may be compared with a visibility criterion.The observational data base greatly expands on previously published reports.
... Examples of these astronomical phenomena lie in the use of astronomical phenomena to determine the exact and correct direction of the Qiblah [138,156,[158][159][228][229], also the use of sundials [230][231][232][233][234] and astrolabes [235][236][237][238][239] in mosques to adjust prayer times [240][241][242], as well as tracking and monitoring the movement of celestial objects in their cosmic cycles and astronomical phases [243][244], in addition to observing, tracking and monitoring the motion of the sun, as well as the orbits and phases of the moon [22, 129, 145-146, 183-185,187,192,245], this in order to be used in the process of timekeeping [145][146] and to be benefited from them in adjusting prayer times [167], where there is a need for determiningand adjusting the time of certain acts of worship in Islamic beliefs [246], such as prayer times associated with the movement of the sun, as well the length of shadows that were differentiated. It should be noted that some acts of worship in Islamic beliefs such as fasting or Sawm, Hajj, and Zakat (Zakah) [247][248] which were associated with monitoring the crescent, or the so-called crescent observation and also linked to determining the beginnings and ends of Arab months [249][250][251][252][253][254]. It is worth mentioning that during 15th century, it is believed that Samarkand was known as the astronomical capital of the world, where by the observations of astronomers in observatory of Samarkand and through the astronomical tables, it was clear that the planet of Saturn, the sixth planet from the sun in the solar system, takes about 29 years amongst the constellations and stars to come back to the same location, this was its revolution period, a period of 29 years around the Sun, and this was the expected length period of Saturn revolution as described by the astronomers and astronomical tables in the observatory of Samarkand [255][256][257]. ...
... That is, we look at certain values such that the moon is bright enough, or the sky is dark enough for the crescent moon to be seen. for example, the Babylonians used age and lag time as a measure of brightness of the moon and the sky, respectively (Bruin 1977). here the lag time is at least 48 min after sunset, and this value has changed since. ...
Article
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Many astronomers have studied lunar crescent visibility throughout history. Its importance is unquestionable, especially in determining the local Islamic calendar and the dates of important Islamic events. Different criteria have been used to predict the possible visibility of the crescent moon during the sighting process. However, so far, the visibility models used are based on linear statistical theory, whereas the useful variables in this study are in the circular unit. Hence, in this paper, we propose new visibility tests using the circular regression model, which will split the data into three visibility categories; visible to the unaided eye, may need optical aid and not visible. We formulate the procedure to separate the categories using the residuals of the fitted circular regression model. We apply the model on 254 observations collected at Baitul Hilal Teluk Kemang Malaysia, starting from March 2000 to date. We show that the visibility test developed based on elongation of the moon (dependent variable) and altitude of the moon (independent variable) gives the smallest misclassification rate. From the statistical analysis, we propose the elongation of the moon 7.28°, altitude of the moon of 3.33° and arc of vision of 3.74 at sunset as the new crescent visibility criteria. The new criteria have a significant impact on improving the chance of observing the crescent moon and in producing a more accurate Islamic calendar in Malaysia. ABSTRAK Ramai ahli astronomi telah mengkaji kebolehnampakan bulan sabit sepanjang sejarah. Kepentingannya tidak dapat dipertikaikan, terutama dalam menentukan kalendar Islam tempatan dan tarikh peristiwa penting Islam. Kriteria yang berbeza telah digunakan untuk meramalkan kemungkinan kebolehnampakan bulan sabit semasa proses pencerapan. Walau bagaimanapun, setakat ini, model kebolehnampakan yang digunakan adalah berdasarkan teori statistik linear, sedangkan pemboleh ubah penting dalam kajian ini adalah dalam sukatan membulat. Oleh itu, dalam kertas ini, kami mencadangkan ujian kebolehnampakan baru menggunakan model regresi berkeliling, yang akan membahagikan data menjadi tiga kategori kebolehnampakan; dapat dilihat dengan mata kasar, mungkin memerlukan bantuan optik dan tidak kelihatan. Kami memformulasi prosedur tersebut untuk memisahkan kategori menggunakan sisa model regresi berkeliling yang sesuai. Kami mengaplikasikan model tersebut dalam 254 pemerhatian yang dikumpulkan di Baitul Hilal Teluk Kemang Malaysia, bermula dari Mac 2000 sehingga kini. Kami menunjukkan bahawa ujian kebolehnampakan dibangunkan berdasarkan pemanjangan bulan (pemboleh ubah bersandar) dan ketinggian bulan (pemboleh ubah bebas) memberikan kadar salah pengkelasan terkecil. Daripada analisis statistik, kami mencadangkan pemanjangan bulan pada 7.28°, ketinggian bulan 3.33° dan aras penglihatan 3.74° ketika matahari terbenam sebagai kriteria baharu kebolehnampakan bulan sabit. Kriteria baharu ini memberi kesan yang besar dalam meningkatkan peluang melihat bulan sabit dan menghasilkan kalendar Islam yang lebih tepat di Malaysia studied.
... Naturally it is hard to unify a lunar crescent visibility. When the conjunction happened in the summer and winter solstices, then the hilal cannot be seen by some people in the northern or southern hemisphere [1], and when the conjunction happened in the summer and winter solstices, the lunar crescent visibility will be more than 24 hours after conjunction, the crescent visibility during the day time, the sky is extremely very bright [2]. The different sky brightness between aphelion and perihelion passage of the earth. ...
Article
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We present a preliminary result on criteria of a young moon crescent visibility and the beginning of new month in Hijri calendar. We present our study of all possibility of moon's astronomical position at sun-set time in one diagram. The altitude of the moon vs the elongation between the moon and the sun, and the azimuth differences between the sun and the moon plotted over the diagram. The purpose of constructing the diagram is to see easily all used/proposed criteria of the beginning of the Hijri' month on a single diagram, then the position of the new young crescent of the moon on the diagram can be analysed easily, whether it is included in criteria of young moon crescent (hilal) visibility or excluded. Some cases of Hijri calendar of 2017 – 2018 in Indonesia are examined and provided in this paper.
... Kriteria tersebut adalah daripada al-Qallas (King, 1987), al-Khawarizmi (Louay J. Fatoohi, 1998), Ibnu Yunus (King, 1988), Caldwell (Caldwell, 2011),Fotheringham (Fotheringham, 1910), Maunder (Maunder, 1911), Danjon (Danjon, 1936), Ilyas (M. Ilyas, 1988), McNally (McNally, 1983), Bruin (Bruin, 1977), Odeh (Odeh, 2004), ...
Article
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In the early stage of Islam, the Hijriah date is determined by new moon observation every 29 th day cycle of moon phase. However, the expansion of Islam to another civilization and its transition to the next age contribute to differentiating cultures and practices of determining the date of Hijriah that is unique from one to another. The instance for the differentiation of cultures and practices can be seen in diverse implementation of new moon visibility criteria in determining the date of Hijriah. The question is, how differentiation of practice in determining the date of Hijriah particularly the new moon visibility criterion exactly happens? To provide a clarification to this
... Kriteria tersebut adalah daripada al-Qallas (King, 1987), al-Khawarizmi (Louay J. Fatoohi, 1998), Ibnu Yunus (King, 1988), Caldwell (Caldwell, 2011),Fotheringham (Fotheringham, 1910), Maunder (Maunder, 1911), Danjon (Danjon, 1936), Ilyas (M. Ilyas, 1988), McNally (McNally, 1983), Bruin (Bruin, 1977), Odeh (Odeh, 2004), ...
... Dengan bertambahnya data empirik, nilai-nilai yang diperoleh secara teoretik tersebut akan dapat diverifikasi. Bruin (1977) Oleh Penulis kondisi saat Dm mencapai nilai positif terbesarnya ini didefinisikan sebagai best time. Sejauh cuaca mendukung (tidak ada liputan awan di arah pandang hilal atau tidak turun hujan), atmosfer yang bersih, dan tidak ada halangan objek-objek terestrial (gunung, gedung, dan lain-lain) di arah posisi hilal berada, besar peluang untuk dapat mengesani sosok hilal pada saat tersebut. ...
Article
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ABSTRAKPerbedaan dalam memulai dan mengakhiri ritual kolosal (puasa Ramadhan dan Idul Fitri ataupun Idul Adha) di kalangan umat Islam Indonesia masih berpotensi untuk terjadi pada masa depan selama belum disepakatinya suatu kriteria tunggal bagi visibilitas hilal yang memiliki landasan ilmiah kokoh. Dalam naskah ini diusulkan sebuah kriteria visibilitas hilal bagi wilayah Indonesia berdasarkan data kesaksian mengamati hilal yang dikompilasi oleh Kementerian Agama Republik Indonesia dan sumber lain yang telah dihimpun lembaga Rukyatul Hilal Indonesia. Kriteria yang diusulkan tidak semata berdasarkan konfigurasi geometri ketiga benda langit terkait (Matahari–Bumi–Bulan), namun turut mempertimbangkan faktor kecerahan langit senja dan langit malam. Agar dapat diamati, umur Bulan minimal pascakonjungsi dan elongasinya berturut-turut harus lebih besar dari 15 jam dan 80. Beda tinggi (ARCV) minimal sebesar 110 untuk beda azimut (DAZ) 00, dan berkurang dengan membesarnya beda azimut Bulan–Matahari. Selain itu berhasil diperoleh penjelasan teoretik atas kriteria ketinggian minimal hilal 20 yang selama ini dianut Kementerian Agama RI. Hasil yang diperoleh ini dapat menjadi pijakan sementara bagi sebuah kriteria visibilitas hilal di Indonesia yang valid secara keilmuan. Dengan terus bertambahnya data observasi dan semakin baiknya pemodelan matematis, penerimaan umat Islam terhadap suatu kriteria tunggal yang teruji akurat diharapkan dapat ABSTRACTWe proposed hilal visibility criteria for area near to equator. The criterion is not based on geometric configuration of the Sun–Earth–Moon only but considered the contribution of twilight and night sky brightness also. The data came from hilal observation reports compiled by Religion Ministry of Republic of Indonesia and Rukyatul Hilal Indonesia (Indonesia Hilal Observation) organization. In order to be observed, the age of the Moon after conjunction and its elongation should be greater than 15 hours and 80 respectively. The relative altitude (ARCV) is 110 for relative azimuth (DAZ) of 00, and decreases with larger relative azimuth. We also provide theoretical explanation for hilal minimum altitude criterion of 20 that have been adopted by the Ministry of Religious Affairs. Based on current available data, the proposed criteria can be used as the one of scientifically-based hilal visibility criterion. With the growing of hilal observation data comes from around Indonesia, we can improve and test the validity of the criteria based on model of Kastner. Then we can be optimistic about Muslims acceptance of unique criterion for hilal visibility in Indonesia.
... That is, we look at certain values such that the moon is bright enough, or the sky is dark enough for the crescent moon to be seen. for example, the Babylonians used age and lag time as a measure of brightness of the moon and the sky, respectively (Bruin 1977). here the lag time is at least 48 min after sunset, and this value has changed since. ...
Article
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The visibility of lunar crescent has been explained in Islamic Law (fiqh) by previous scholars. Until today, the explanations which were nuance in qualitative sense are still provide vacuum and need to be studied critically with different method particularly in quantitative approach. Therefore, this paper will present the application of scientific approach using sky illumination measurement to explain lunar crescent's visibility. The approach combines computational and observational technique will help fiqh in explaining the phenomenon explicitly and strengthen it with empirical descriptions. The sky illumination measurement was performed using a light meter in Teluk Kemang, Malaysia from 2007 until 2009. The authors employed the observational data to obtain the estimate values of sky illumination for the day which lunar crescent was seen from 1972 until 2009. The analyses of the values then were correlated with relative altitude and sun depression angle. The authors found that the range of sky illumination for lunar crescent to be seen is 2.95-92.80 lux. For the highest sky illumination value (92.80 lux), relative altitude should be. 5° and the depression angle should be. 0.5°.
... 6 The most commonly used criterion of this kind is the one of Schoch. 7 Bruin chose a different ansatz in 1977, 8 which was later modified by Schaefer. 9 Yallop tried to merge the approach of Bruin with the criterion of Schoch, 10 from whom he adopted the values for the minimal altitude of the Moon at a certain difference in azimuth. ...
Article
The aim of the present paper is to establish a lower boundary condition of a possible successful sighting of the lunar crescent based on Babylonian predictions and observations. This means that all Egyptian chronological options showing deviations in positive direction with visibilities below this boundary condition will be dismissed as impossible. Although a theoretical limit of 10° for the visibility criterion, i.e. a minimum lagtime between sunset and moonset of 40 minutes, is mentioned in text TU 11, the Babylonian Astronomical Normal Star Almanacs contain several predictions for first or last visibility with values smaller than 10° and the Astronomical Diaries a few such observations. Thus, a value of 10° for the lagtime is an inappropriate lower boundary condition which cannot be used as knock-out criterion for Egyptian chronological options based on lunar data.
... But in the long term, the database collected by the system may support for research on data processing techniques. Accordingly, research on the crescent visibility criteria can also be conducted (for more details, see for example, references4567). In addition, a more sophisticated system is now undertaken at the Bosscha Observatory. ...
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We present a progress report on the development of information system of lunar crescent astronomical observations which will be largely accessible for public domain. This consists of calculations of the Moon’s ephemeris as well as systematic real-time lunar crescent observations. A well suited small telescope, equipped with a simple digital detector, is connected to a server to provide information on lunar crescent observations. The system has been used and worked well. The only constraint is poor weather condition. Network of small telescopes, installed at various locations in Indonesia, are currently planned to provide plethora of data. In the long term, this will be used to help to determine the astronomical visibility criteria of lunar crescent for Islamic calendar.
... Another equivalent method is that the angle of separation of the Moon and the Sun should be at least 12 degrees at sunset. Several algorithms exist today to predict the first visibility of the crescent (Bruin 1977; Yallop 1998). Some of these algorithms use just the old criteria methods described above without taking into account the observing conditions. ...
Article
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The Islamic society has great ties to astronomy. Its main religious customs (start of the Islamic month, direction of prayer, and the five daily prayers) are all related to two main celestial objects: the Sun and the Moon. First, the start of any Islamic month is related to the actual seeing of the young crescent after the new Moon. Second, the direction of prayer, i.e., praying towards Mecca, is related to the determination of the zenith point in Mecca. Third, the proper time for the five daily prayers is related to the motion of the Sun. Everyone in the society is directly concerned by these customs. This is to say that the major impetus for the growth of Islamic astronomy came from these three main religious observances which presented an assortment of problems in mathematical astronomy. To observe these three customs, a new set of astronomical observations were needed and this helped the development of the Islamic observatory. There is a claim that it was first in Islam that the astronomical observatory came into real existence. The Islamic observatory was a product of needs and values interwoven into the Islamic society and culture. It is also considered as a true representative and an integral par of the Islamic civilisation. Since astronomy interested not only men of science, but also the rulers of the Islamic empire, several observatories have flourished. The observatories of Baghdad, Cairo, Córdoba, Toledo, Maragha, Samarqand and Istanbul acquired a worldwide reputation throughout the centuries. This paper will discuss the two most important observatories (Maragha and Samarqand) in terms of their instruments and discoveries that contributed to the establishment of these scientific institutions.
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Middle Age lunar crescent visibility criterion is criterion that was produced during 8 th until 17 th century. This includes al-Khawarizmi lunar crescent visibility criterion in 8 th century until al-Lathiqi lunar crescent visibility criterion in 17 th century. Numbers of review on mathematics and astronomy during the Middle Age, however the number of review that specifically written for Middle Age lunar crescent visibility criterion limited, with majority of review is written to study the historical of Middle Age science, astronomy, mathematics and geography as a whole, and not converge on lunar crescent visibility criterion.. Therefore, this article aimed to provide a review on Middle Age lunar crescent visibility criterion. The review is conducted using literature analysis, snowball literature search and specific inclusion and exclusion criteria. The review is performed based on 13 works on lunar crescent visibility criterion that pass the selection criteria. The review found out that most of the lunar crescent visibility criterion is based on al-Khawarizmi arc of separation and solar longitude, lunar crescent visibility criterion, with exception on Ibn Tariq, Ibn Qurra and Ibnu Yunus lunar crescent visibility criterion that adopt angular distance or elongation. The review suggest that a new outlook on Middle Age lunar crescent visibility criterion study can be done, by conducting an assessment on new data of moonsighting, and comparing with modern lunar crescent visibility criterion research.
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For the central zone of the Earth (approximately 50ºN-50ºS), Islamic months have lengths of 29 and 30 days depending on the place of Earth from where we observe the first lunar crescent. We verify that all the lunar months have two durations for the central zone, one of 29 days and the other of 30 days. For higher latitudes (50º N or S to 61.5º N or S), we find that months can have 28 and 31 days lengths. We determine the length of the lunar months using the Month Change Line concept, applying the extended Maunder criterion.
Research Proposal
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Brief report on how to calculate the first visibility of the Moon crescent. We warn against the misinterpretation of Blackwell's threshold visibility experiment. We state that the width of the first lunar crescent is less than the resolving power of the human eye, so the determining factor for visibility is the illuminance of the Moon and not its brightness.
Article
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The method used to determine the beginning of the Islamic month which refers to the hilal regularity is called rukyat. The central issue of rukyat disruption is the problem of visual contrast of sky twilight, namely the difference in light or the color between the object and the foreground. The hilal (the new crescent moon) is dim, thin, and its color is almost the same as the sky around it so it makes the human eyes in a normal state unable to see directly the hilal without using the tools. Moreover, the technology of rukyat has developed significantly by discovering the optical technology named the rukyat telescope. However, this telescope is not able to identify hilal (the new moon), because it is only functioned to collect the light; so, when the twilight (syafak) light is strengthened, the hilal light is also equally strengthened. Furthermore, rukyat technology that is possibly used is digital imaging assisted by software that works to increase the light contrast so that the hilal can be seen by the visual eyes. Finally, digital imaging technology has an important role as a media verifier of the testimony stated by someone seeing the hilal, contrarily, its validity is doubtful. In responding to the development of technology used for finding the new crescent (rukyatulhilal), both classical and contemporary fiqh scholars give positive responses related to the use of rukyat tools that aim to facilitate the process of seeing the crescent (rukyatulhilal), especially in terms of clarifying the crescent sight object so that the new moon can be seen with the visual eye.
Article
The first visibility of the lunar crescent signals the start of a new month in the Islamic calendar. The eminent astronomer Ḥabash al-Ḥāsib sib developed a method of uncompromising complexity for predicting the visibility of the lunar crescent. He derived his threshold value from a moonwatch carried out at different places in Iraq on November 17th, 860 CE. We will allude to a few modern visibility criteria as well and highlight the uncertainties of today’s calculations when converting historical Arabic into Julian or Gregorian dates. Tables of first visibility of the lunar crescent for different locations are provided for the purpose of date conversions. Since the Islamic calendar was based on the observation of the lunar crescent, historical dates imply information on positive and negative sightings of the lunar crescent. From such information estimations of cloudiness in different regions of the Islamic world can be extracted.
Article
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في هذه الدراسة تم التركیز في هذه الدراسة على معرفة المستوى المعرفي الفلكي لدى طلبة كلیات الشریعة وعلوم القران في محافظة الانبار بشكل عام ومن خلال المحاور التالیة )محور المفاهیم الأساسیة, ومحور الفتاوى, ومحور القرآن الكریم(. یتكون مجتمع الدراسة من طلبة كلیة العلوم الإسلامیة, وكلیة التربیة في جامعة الأنبار وكلیة الإمام الأعظم في دیوان الوقف السني, حیث تم اعتماد عینات عشوائیة في الكلیات أعلاه للمرحلتین الدراسیتین الأولى والرابعة بلغ عدد أفرادها ) ( 245طالبا وطالبة. وقد تم خلال هذه الدراسة إعداد استمارة استبیان, ومن ثم جمع البیانات وتحلیلها ومناقشة نتائجها. من خلال النتائج وجد أن مستوى المعرفة الفلكیة لدى طلبة العینة بشكل عام كان % 42.5لجمیع محاور وفقرات عینة الدراسة وهي اقل بكثیر من حد النجاح وقد تم بیان أسباب ذلك التدني في المستوى الفلكي. وأما نتائج محاور الاختبار الثلاثة )التعاریف والمفاهیم, الفتاوى والأحكام, القرآن الكریم( فقد كانت النتائج متفاوتة في إجابات الطلبة, حیث بینت النتائج أن أعلى الدرجات كانت في محور الفتاوى والأحكام بنسبة % 53وهي أعلى من حد النجاح, واقلها في محور التعاریف والمفاهیم بنسبة % 13ویعود ذلك أیضا إلى أسباب تم بیانها في هذه الدراسة. أوضحت الدراسة أیضا أن هناك فروق ذات دلالة إحصائیة حسب متغیرات الجامعة, التخصص في الثانویة, المستوى الدراسي, السكن, الجنس. كما تبین وبشكل عام إن المستوى المعرفي الفلكي لدى طلبة عینة الدراسة كان دون مستوى الطموح, وكان دور الجامعة ضعیف في رفع المستوى المعرفي الفلكي على الرغم من أن طلبة كلیات الشریعة هم بأمس الحاجة إلى المعرفة العلمیة الفلكیة
Article
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Setiap kaedah penentuan kenampakan anak bulan mempunyai fungsi tersendiri. Fungsi itu dapat dijelaskan berasaskan metodologi mengenal alam. Dalam penelitian ini, metodologi mengenal alam yang dikemukakan oleh Daud al-Fatani diaplikasikan untuk menjelaskan fungsi berkenaan. Pengumpulan data dalam kajian ini adalah berdasarkan metode dokumentasi, manakala analisis data adalah berasaskan metode analisis kandungan. Hasil kajian mendapati kaedah hisab adalah ẓannī yang lebih kuat berbanding kaedah rukyah tetapi ia lebih lemah berbanding kaedah istikmal. Sehubungan itu, fungsi kaedah hisab hanya sebagai pengesah dan penafi kepada laporan cerapan terutamanya apabila menentukan kenampakan anak bulan bagi bulan Ramadan, Syawal dan Zulhijjah. Each method of determining the crescent's visibility has its own function. The function can be explained based on the methodology to know the universe. In this study, the methodology to know the universe as presented by Daud al-Fatani is applied to elucidate the function. Data collection in this study is based on the documentation method, while data analysis is according on content analysis method. The study found that the calculation method is conjecture (ẓannī) which is stronger than the observational method but it is weaker than the rounding method (istikmal). Accordingly , the calculation method can be function only as a verifier and a disclaimer to the observation report primarily when determining the crescent's visibility for the month of Ramadan, Syawal and Zulhijjah.
Chapter
In this chapter, we deal with the ways in which the objects described in Chapter 2 can be observed and the conditions affecting those observations.
Article
This article considers three questions associated with Ptolemaic-Roman lunar chronology: did the temple service begin on Lunar Day 2; were lunar phases determined by observation and/or cyclically; how accurate were lunar observations? In the introduction, Babylonian and modern observations of old and new crescents are analyzed to obtain empirical visibility lines applicable to Egyptian lunar observations.
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For many years lunar crescent visibility has been studied by many astronomers. Different criteria have been used to predict and evaluate the visibility status of new Moon crescents. Powerful equipment such as telescopes and binoculars have changed capability of observations. Most of conventional statistical criteria made wrong predictions when new observations (based on modern equipment) were reported. In order to verify such reports and modify criteria, not only previous statistical parameters should be considered but also some new and effective parameters like high magnification, contour effect, low signal to noise, eyestrain and weather conditions should be viewed. In this paper a new method is presented for lunar crescent detection based on processing of lunar crescent images. Themethod includes twomain steps, first, an image processing algorithm that improves signal to noise ratio and detects lunar crescents based on circularHough transform(CHT). Second using an algorithmbased on image histogram processing to detect the crescent visually. Final decision is made by comparing the results of visual and CHT algorithms. In order to evaluate the proposed method, a database, including 31 images are tested. The illustrated method can distinguish and extract the crescent that even the eye can’t recognize. Proposed method significantly reduces artifacts, increases SNR and can be used easily by both groups astronomers and who want to develop a new criterion as a reliable method to verify empirical observation.
Article
The visibility of the thin crescent Moon is an important problem for the calendars of many societies, both ancient and modern. With roughly 1 × 109 people of the Islamic faith following the Islamic calendar, this problem is likely to be the one (nontrivial) problem in astronomy that has the greatest impact on our modern world. In the past decade, great advances have been made in the observation and theory of crescent visibility. This paper reports recent observations and analyses. New records have been set for the youngest Moon, with confident sightings at 15-0 hr by John Pierce with unaided vision and at 12-1 hr by Jim Stamm with telescopic assistance. These records can be significantly broken under optimal conditions. Various prediction algorithms are tested with the 294 collected individual observations plus the 1490 observations from the five Moonwatches. The age and moonset-lag criteria are found to be poor, the altitude/azimuth criteria can make a confident prediction only one-quarter of the time, while the best predictor by far is the modern theoretical algorithm.
Article
Science and technology (S&T) are necessary tool for Islamic jurist to examine related issues explicitly. On the crescent visibility issue, the implementation of S&T through astronomical calculation and technological observation is still debated, some accept while others reject. This paper examines the effects that arise from the implementation based on crescent visibility data for the year of 2010. It is identified that S&T can strengthen the method of rukyah, overcoming the indecision and reducing the fallibility both of the observation and of the witness, therefore the juristic result can be issued scientifically. Without the application of S&T, the result might be supported by weak testimonial though the witness is qualified.
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About 70 years ago “André Danjon” a French astrophysicist showed that as elongation of the moon decreases the arc length of crescent gets less too. By studying the recent observational data, he concluded that at 7 degree elongation, the length of arc (cusp to cusp) will reach zero degree. Today, this value is named as Danjon limit, which points to the limit at which the moon crescent is formed. Danjon believed that the effective factor for occurring this limit was the shadows of moon’s mountains. Later researchers have obtained different values for this limit. In this research based on the new data, the decreasing dependence of length of arc versus elongation was obtained. The results show that the Danjon limit is about 5 degrees. The effective factors to form the Danjon limit are then given and discussed. By considering the effects of astronomical seeing and shadows of lunar features, the values of the arc length were calculated and compared with the observational data curve. The results of this study show good agreement with the observational data. The present research shows that the above-mentioned effects can reduce the length of arc. The effect of libration and roughness of the lunar terrain of the moon in forming the moon crescent were also considered, and the possibility of observing thinner crescents by photometric model and breaking the Danjon limit were given.
Article
Earliest visibility of the lunar crescent is an important calendrical element. It was needed in all early calendars and remains in use on some lunar calendars today. An astronomical criterion of earliest lunar visibility was therefore evolved quite early, using observations, right from the Babylonian era. Recently, an improved and comprehensive global criterion of earliest visibility, developed by the author, has been used to generate an extensive inverted moonset lag data set. These data, as a function of latitude and season, all for the first time provide a useful comparison with the simple ancient criterion.
Article
Many methods for predicting lunar first visibility have been proposed throughout history and new models are still being developed. All these models have to be compared with the published observations to test their validity. In this paper, we use our photometric model to predict the naked-eye first visibility of the lunar crescent. We find that an elongation of about 7. 5° is the lowest naked-eye visibility limit. We also find that the lunar crescent may be seen - with a suitable telescopic magnification and ideal local conditions - when the Moon is about 5° from the Sun. Consequently, the thin lunar crescent may be seen in a telescope even at new moon when the Moon is at its greatest inclination.
Article
A review is presented of the lunar-calendar criteria for determining when a lunar month begins, from the oldest proposals to the most recent (the Saudi criterion). The new Saudi criterion, which depends on the probability of seeing the crescent rather than the capability (first visibility), reduces the errors that occurred with the old Saudi criterion and others.
Book
Exploring Ancient Skies uses modern science to examine ancient astronomy throughout the World, that is, to use the methods of archaeology and insights of modern astronomy explore how astronomy was practiced before the invention of the telescope. It thus reviews an enormous and growing body of literature on the cultures of the ancient Mediterranean, the Far East, and the New World, particularly Mesoamerica, putting the ancient astronomical materials into their archaeological and cultural contexts.
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The concept of "best time" for the first visibility of the thin crescent moon developed by Bruin, Schaefer and Yallop did not consider the elevation of the site of observation. Our first estimation -- after analyzing some documented observations -- is that "best time" is directly proportional to site elevation and inversely proportional to moon altitude. For moderate elevation sites (less than 1000m) the crescent could be first seen shortly after sunset. However, for higher elevations (around 2000m) the crescent could be first seen shortly before moonset. By using our first visibility photometric model, the extensive data of Blackwell 1946 experiment and the measured twilight sky brightness of our site (1990m), we find that the optimum lunar altitude for first visibility is about 2 degrees, no matter what the lunar elongation is.
Article
Celestial visibility is the study of the limits of observability of objects in the sky, with application to deducing the truth about historical events or to the derivation of astronomical information of modern utility. This study is based on what is seen by ordinary humans, either in their everyday lives or at times of historical events. The results of such studies have more relevance to non-scientists than does any other area of astronomy. Celestial visibility is a young discipline in the sense that the number of interesting applications with simple solutions outnumber the solved problems; it is a broad interdisciplinary field that involves work with astronomy, meteorology, optics, physics, physiology, history, and archeology. Each of these disciplines contribute specialized mathematical formulations which quantify the many processes that affect light as it leaves a source, traverses the atmosphere, and is detected by the human eye. These formulas can then be combined as appropriate to create mathematical models for the visibility of the source under the conditions of interest. These model results can then be applied a wide variety of problems arising in history, astronomy, archeology, meteorological optics, and archeoastronomy. This review also presents a dozen suggestions for observing projects, many of which can be directly taken for individual study, for classroom projects, or for professional research.
Article
MATHEMATICAL astronomy owes an enormous debt to the institution of lunar calendars. The apparently simple question whether a month will be full or hollow, i. e., whether the new crescent will be visible on the evening of the 29th or of the 30th day, led Babylonian astronomers of the fourth century b.c. to ingeniously constructed arithmetical devices which enabled them to compute ephemerides of great accuracy for the movement of the sun and the moon. We know practically nothing about the underlying concepts concerning the physical nature of the treated phenomena. In contrast, we are well informed about the geometrical interpretation which formed the basis of the corresponding theory of Greek astronomers, at least so far as reflected in the Almagest. Finally, Ptolemy himself brought the theory of the planetary movement to the same level which the lunar theory had reached centuries before.
Article
With a recording photometer of photopic sensitivity, measurements were made of many points in the sky during twilight for solar altitudes H = +5° to -15° for clear air and no clouds at two stations, one in Maryland, altitude 30 meters, and one on Sacramento Peak, New Mexico, altitude 2800 meters. The sky polarization on the meridian through the sun, and the illumination on a plane at various orientations exposed to the sky, were also recorded. For H from about -3° to -11° the entire sky changed in brightness at about the same rate of a factor of 10 for each 2° change in H. Except at the horizon the Sacramento Peak sky was about ⅔ to ½ as bright as the Maryland sky because of clearer air; at the horizon the two were about the same. At Sacramento Peak the ratio of the polarized components reached a minimum of about 0.06 at the zenith for H = -3°.