Dating Historical Arabic Observations (original) (raw)
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Islamic Historical Review on Middle Age Lunar Crescent Visibility Criterion
Journal of Al-Tamaddun
Middle Age lunar crescent visibility criterion is criterion that was produced during 8th until 17th century. This includes al-Khawarizmi lunar crescent visibility criterion in 8th century until al-Lathiqi lunar crescent visibility criterion in 17th 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 th...
Some early Islamic tables for determining lunar crescent visibility
Annals of the New York Academy of Sciences, 1987
When you've seen one, you've seen 'em all. U.S. President Ronald Reagan, in relation to the endangered redwood trees of California; also heard from Ted Kennedy after a lecture of mine on Islamic tables for timekeeping. 190 ANNALS NEW YORK ACADEMY OF SCIENCES TABLE 1 al-KhwiirizmTs Crescent Visibility Table A: MS Paris B.N. ar. 6913, fol.
Arc-Light. Application to the Islamic Calendar
We show techniques for finding the arc-light, or angle between the centers of the Sun and the Moon. We describe the periodicity of the Moon's ecliptic latitude and its effect on the arc-light. We verify that the arc-light at the New Moon time has a periodicity of approximately 173.5 days. We define the topocentric New Moon, which occurs when there is a relative minimum of the topocentric arc-light.
Eclipses in the Middle East from the Late Medieval Islamic
2013
This paper deals with the analysis of data obtained from observations of two sets of three lunar eclipses in the Late Medieval Islamic Period. The first trio consists of the lunar eclipses of 7 March 1262, 7 April 1270 and 24 January 1274, observed by Muḥyī al-Dīn al-Maghribī from the Maragha Observatory (in northwestern Iran), and the second includes those of 2 June and 26 November 1406, and 22 May 1407, observed by Jamshīd Ghiyāth al-Dīn al-Kāshī from Kāshān (in central Iran). The results are that al-Maghribī"s values for the magnitudes of these eclipses agree excellently with modern data, and his values for the times when the maximum phases occurred agree to within five minutes with modern values. Al-Kāshī"s values for the times of the maximum phases show a rather larger divergence from modern data, varying from about ten minutes to about one hour. The errors in all six values both astronomers computed from their own solar parameters for the longitude of the Sun at the instant of the opposition of the Moon to the Sun in these eclipses remain below ten minutes of arc. The motivation for doing these observations was to measure the lunar epicycle radius r in the Ptolemaic model. Al-Maghribī achieved r = 5;12 and al-Kāshī r ≈ 5;17, 1 in terms of the radius of an orbit of R = 60 arbitrary units. It is argued that comparing with modern theory, neither of these two medieval values can be considered an improvement on Ptolemy"s value of r = 5;15.
Are Islamic Legacy Calendars of the Lunar Type, Really? Measurement of the Deviation
JISC, 2024
Background and Purpose: This study aims to demonstrate that the so-called Islamic legacy calendars are of the Gregorian-like type far from corresponding to the properties of the synodic lunar month. This unexpected result provided the first stone from which the search for a coherent definition of legacy criterion has been undertaken in this work. Material and Methods: To this end, distributions of time lag (∆t 0), the time distance between the lunar conjunction (LC) and the first lunar day of the month, were processed and used to estimate the 1 st −Day rejection index (R I) for four computerized calendar paradigms used in Lausanne city, between1938 and 2038. Those estimates measured the deviations from the lunar synodic properties caused by the underlying hypotheses. In addition, new synoptic figures of the projected 2023/1444H Ramadan calendars in twelve pilot cities were computed to highlight the fundamental reason for mismatch along with specific assessment. Those figures also aimed to illustrate the competitive effects of four environmental parameters on final issues, namely: LC, latitude, time zone and season. Results: Several results were found: R I was ranging between 45% and 90% while the corresponding rejection thresholds were between 8h and 18h. The synoptic figures, while fully explaining the similarities and differences between the calendars in and between cities with all their respective 1 st −Day dates being summarized in "Confusion Tables", they also contributed to demonstrate that all the residual flaws of the Islamic calendars were caused by explicit and implicit assumptions of unfounded "day reference times" (DRT), as if the lunar context was assimilated to a Gregorian-like one. Conclusion: The results were finally analyzed within the framework of the "inclusive science approach" (ISA) and a new proposal was made in favor of a "single and universal" Islamic calendar legacy definition, which conforms on the one hand, to the properties of the lunar synodic month and on the other hand, to lunar Islamic requirements.
Timekeeping at Night by the Moon in 13th-Century Yemen and Beyond
Suhayl (International Journal for the History of the Exact and Natural Sciences in Islamic Societies), 2023
A joint paper with Petra G. Schmidl centered on al-Ashraf ῾Umar’s Tabṣira, Chapter xxiii. This article explores methods for determining moonrise and moonset as evidenced within a range of pre-and early modern sources originating from Islamicate societies (time-keeping, agriculture, anwa', zījes,...). The present article suggests a categorisation of the diverse methods predicated on various factors such as exactitude, complexity, state of completeness, literary formats, and audience.
This report briefly analyses two questions: “What is the ruling for sighting the moon in Ramadan according to the four madhabs?” and, “Is calculation enough or sighting the moon necessary according to the four madhabs?” Firstly, the religious source texts that were used by these four major Sunni schools of law to formulate their respective rulings will be described. The specific rulings of each of the four schools will then be compared and finally the place of calculation as a method for determining the start and end of a lunar month assessed.