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The aim of this paper is to discuss the dating recently proposed by Davoust (2024) for the astrolabe of the Preaching Friars in the Musée des Arts Précieux in Toulouse (France). The proposed dating (1550 +/- ?) is based on an assessment of precession. I show that a detailed study of the star positions on the rete, supplemented by various scientific and historical criteria, suggests that this dating is not acceptable; in fact, it remains uncertain, but we can assume that the instrument was made one or two centuries earlier [ABSTRACT FROM AUTHOR]

Instruments and tables in Regiomontanus' calendar published in 1474 are analysed and explained. It is shown that Regiomontanus used the Alfonsine Tables corrected for the longitude time difference between Toledo and Nuremberg. It is also shown that for the syzygy and eclipse times he used apparent solar times. The syzygy tables of George Peurbach may have been used to correct from mean to true syzygies. The calendar also contains an instrument for converting between equal and unequal times, a volvelle for finding the true longitude of the Moon, a quadrant tool for the construction of a horizontal sundial, and a universal vertical sundial. The construction and workings of these instruments are analysed. [ABSTRACT FROM AUTHOR]

Diego de Torres Villarroel publica en 1724 un almanaque titulado Melodrama astrológica: teatro temporal y político. El opúsculo, además de granjearle notoriedad al presuntamente vaticinar en él la muerte del rey Luis I, supone uno de los primeros intentos por insertar contenidos literarios en los pronósticos astrológicos. Este artículo trata de demostrar que, frente a las teorías que ven en el "modelo literario" un hallazgo original e inesperado, Torres se inspira en ciertas fórmulas que algunos autores de su tiempo practican con éxito en otras partes de Europa, concretamente en los Estados italianos. Diego de Torres Villarroel published in 1724 an almanac entitled Melodrama astrológica: teatro temporal y político. The chapbook, besides helping him to gain fame by having supposedly predicted the death of King Louis I, is one of his first attempts at incorporating literary content into astrological predictions. This article aims to demonstrate that, contrary to those critics who see in the "literary model" an original and fortuitous discovery, Torres is inspired by certain formulas that some other contemporary authors were successfully practicing in Europe, specifically in the Italian States. [ABSTRACT FROM AUTHOR]

The total solar eclipse on July 29, AD 1478, went unnoticed by most of Europe. Although several scholars accurately predicted it, very few observations made by professional astronomers have survived, and these contain very little relevant information. In contrast, several observations, many of which unknown or unpublished, made by casual eyewitnesses have reached our days from the different kingdoms of the Iberian Peninsula in the 15th century. We present six such observations. These descriptions, collected in observations, chronicles, or diaries, although not professional, provide interesting information that, in some cases, lead us to obtain valid values for the Δ T parameter. [ABSTRACT FROM AUTHOR]

The codex kept at the Arnamagnean Institute, in Copenhagen, with the number 805 4º (København, Det Arnamagnaeanske Institut, Københavns Universitet, AM 805 4º), contains a combination of texts featuring legal and short historiographic pieces. In the latter we find a few astronomical references, among them a contemporary mention of the solar eclipse of June 3, 1239 containing what seems to be a reference to the solar corona. This reference could be added to the only other commonly accepted timed report of the corona from medieval times in the Annales Sangallenses regarding the total solar eclipse of the year AD968. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Social Sciences (IJSS) / Uluslararasi Sosyal Bilimler Dergisi is the property of International Journal of Social Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article explores the works of four Jewish intellectuals who lived in or near Avignon at the end of the fourteenth century: Isaac de Lattes, Joseph Kimḥi, Eliezer Crescas, and Jacob Salomon. Each of these authors wrote a different type of rabbinic book, shedding light on shared themes and concerns that dominated their city. Their works express—sometimes explicitly, but often implicitly and through their very structure—deep-seated anxieties about the state of Jewish knowledge and communal memory in late medieval Provence. Their concerns with the construction of identity, magic, patronage, and the preservation of knowledge all set the stage for the enigmatic Moses Botarel. Shameless self-promoter and ingenious literary forger, Botarel served as a mirror of the achievements and vulnerabilities of late medieval rabbinic culture in Provence. [ABSTRACT FROM AUTHOR]

Dale Kedwards introduces Cluster 1 of Interfaces 8, on the topic of The Astronomical Imagination in Literature through the Ages.

This article is devoted to a thirteenth-century Latin text on how to construct, set up, and use a version of the so-called armillary instrument (instrumentum armillarum), which was first described in Ptolemy's Almagest as a tool for measuring ecliptic coordinates. Written in 1264 by Guillaume des Moustiers, bishop of Laon, this hitherto unstudied Tractatus super armillas survives in a single manuscript, where it is accompanied by a copious set of glosses. The text and its glosses jointly offer an unusually detailed account of the instrument's material aspects and methods of assembly. In addition, they reflect a keen awareness of the potential sources of error that may arise in the context of astronomical observation, while making suggestions on how these errors may be minimized or avoided. The Tractatus super armillas accordingly is a valuable source on the observational side of medieval European astronomy, which has often been minimized in modern historical accounts. [ABSTRACT FROM AUTHOR]

A unique source on the practical aspects of the scientia astrorum (astronomy and astrology) in medieval Europe has come down to us in the shape of a letter written shortly after 1246 by John of London, an astronomer based in Paris. John used the letter to answer eight questions on technical problems posed to him by his addressee, a certain R. de Guedingue, with subject matters ranging from the rate of precession to the dates of the so-called Dog Days. The article makes this source available via a critical edition (based upon three manuscripts) and an accompanying English translation. An introduction discusses the background and transmission of John's letter as well as the identities of the letter writer and addressee. The edition and translation are followed by commentaries elucidating the background to each of the eight questions and John's answers to them. [ABSTRACT FROM AUTHOR]

This article examines the role of memory techniques in medieval astronomy. Using a mnemonic written by a Franciscan friar c. 1330 as a case study, it shows how astronomers and astrologers simplified the sky for practical purposes, using verses and codes to make their science memorable. The article decodes the mnemonic and its underlying astronomical data, assessing its usefulness, memorability and adaptability alongside some other popular astronomical and calendrical mnemonics of the later Middle Ages. It argues that astronomical learning could be a creative, playful activity. And it situates the astrological practices of this particular friar, who made wide-ranging annotations in a 13th-century astronomical compendium, within the scientific and educational traditions of his order. [ABSTRACT FROM AUTHOR]

The historical evidence from the past two millennia show two problems concerning the star Algol (β Per): First, a critical variation in its brightness from a magnitude m ~ 2 in (1) Ptolemy's Almagest (2nd century AD) and reported by (2) al-Ṣūfī (10th ct.) through its diminution to m = 4 in (3) the star catalog prepared by the Persian astronomers in service of the Yuan dynasty of China in the 13th ct. to becoming brighter, m = 3, as reported by (4) Ibn al-Shāṭir (14th ct.) and (5) Tycho Brahe (16th ct.). In the early modern period, it returned back to m ~ 2, as reported, for example, by Hevelius and Flamsteed (17th ct.), before the discovery of its periodic variability in 1783. Second, al-Ṣūfī reports it as a red star. We present detailed analyses of the sources (3) and (4) for the test of their accuracy and reliability. Our conservative hypothesis concerning the first problem is that the past astronomers observed the star at various phases of its 3-day period of variability. We reject the reddening to have arisen from the extinction due to either the Earth's atmosphere or an interstellar medium. For resolving both problems, we instead speculate on astrophysical explanations for the observations. These are: copious dust produced as a result of arrested coronal mass ejections or pulverized planetary debris that resides close to the central binary before being dispersed; and a much-enhanced accretion rate that lead Algol into a W Ser-like state in which the primary was enveloped in an inflated accretion disk. We draw an analogy between the dimming of Algol and the recent dimming of Betelgeuse in order to highlight the value of historical observations for understanding astrophysical phenomena. [ABSTRACT FROM AUTHOR]

Copyright of Studia Bibliographica Posoniensia is the property of University Library in Bratislava and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The observatory of Ulugh Beg, erected in Samarqand in the 1420s, represents the culmination in the development of astronomical observatories in the Islamic world. After its rediscovery and excavation in the early twentieth century there have been several attempts to reconstruct its appearance and explain how it worked in detail, based on archaeological finds and the analysis of relevant manuscripts. A new look at illustrated copies of an important manuscript provides new, hitherto unmentioned details to the understanding of this instrument. Based on previous reports, we have created a virtual reconstruction of the observatory and the new version of the instrument, from which we have gained new insights. [ABSTRACT FROM AUTHOR]

Geographic and astronomical texts from late-medieval Central Europe frequently give 16 German miles, or miliaria teutonica , as the length of a degree of terrestrial latitude. The earliest identifiable author to endorse this equivalence is the Swabian astronomer Heinrich Selder, who wrote about the length of a degree and the circumference of the Earth on several occasions during the 1360s and 1370s. Of particular interest is his claim that he and certain unnamed experimentatores established their preferred value empirically. Based on an analysis of relevant statements in Selder's extant works and other late-medieval sources, it is argued that this claim is plausible and that the convention 1° = 16 German miles was indeed the result of an independent measurement. [ABSTRACT FROM AUTHOR]

We distinguish between method and methodology and propose to illustrate the claim that methodology is essential to the acquisition of scientific knowledge in all periods. The case in point is Levi ben Gerson (d. 1344) and his creative response to the methodologies in astronomy and cosmology implicit in the works of Ptolemy (second century). We begin by outlining Ptolemy's methodological framework in astronomy, in which one key point is his dependence on his own observations in the first instance, and then on those of others that are consistent with them. In cosmology Ptolemy sought to make his geometric models physical and to account for the transmission of motions to the planets. We then closely examine Levi's ingenious adaptation of Ptolemy's methodologies, which included new planetary models, new cosmological principles, as well as dependence on his own observations for determining planetary parameters, and descriptions of new observational instruments. Levi insisted that the planetary models had to account for observations of both positional data and physical characteristics, in contrast to the theories of his predecessors. We conclude with an analysis of Levi's methodology, emphasizing what made his practice so innovative. Methodology was (and is) the engine of scientific change. [ABSTRACT FROM AUTHOR]

The third book of Levi ben Abraham ben Ḥayyim's voluminous treatise, Livyat ḥen, is a compendium of astronomical and astrological knowledge. In its twelfth chapter, Levi describes a cosmological mechanism that ensures optimal thermal conditions for human life, thereby securing the persistence of the inhabited world. Levi identifies this mechanism with God's general providence, or at least one aspect of it. This article examines the mechanism in detail, and sheds light on Levi's views on the providential role of the celestial bodies. The article also shows that the mechanism was known to Gersonides, and compares it with Gersonides' naturalistic account of providence. In addition, the article identifies some of the scientific sources Levi drew on in compiling the astronomical-astrological section of Livyat ḥen, and provides insight into its overall profile. [ABSTRACT FROM AUTHOR]

This article presents the Hebrew edition and English translation of a treatise on the construction of an astrolabe composed by Joseph ben Solomon Ṭaiṭaṣaq in the last quarter of the fifteenth century, extant in a single manuscript never previously studied. This article ties the astrolabe described by Ṭaiṭaṣaq to a specific tradition of astrolabe construction, which is reflected in two components of the rete and is also witnessed in the Middle Ages in a single Latin/Catalan astrolabe preserved at the Museum of Fine Arts in Boston. Ṭaiṭaṣaq's instrument and the Catalan astrolabe share two remarkable and unique characteristics which may suggest a common literary source for their construction, a common astrolabe workshop, or a common craftsman tradition. [ABSTRACT FROM AUTHOR]

Isaac ben Solomon Ibn al-Ḥadib (or al-Aḥdab) emigrated from Castile to Sicily no later than 1396. In astronomy, his most important work, written in Hebrew, is The paved way (Oraḥ selula), a set of tables for the motions of the Sun and the Moon. Here, we focus attention on his unusual tables for finding the difference in time and the difference in longitude between mean and true syzygy, where syzygy refers to the conjunction and opposition of the Sun and the Moon. It is shown that he took into account the effect of Ptolemy's second lunar model on the velocity of the Moon at syzygy, which was done by very few astronomers in the Middle Ages. It is also noteworthy that he took some parameters from the zij of al-Battānī and others from the Parisian Alfonsine Tables, using them inconsistently in these tables. [ABSTRACT FROM AUTHOR]

Existing research dealing with astronomical observations from medieval Europe have extensively covered topics such as solar and lunar eclipses and sightings of comets and meteors, but no compilation of occultations of planets by the Moon has been carried out and, till now, the data have remained scattered in different publications. The main reasons for this are the small number of observations that has reached us, their limited use for calculation of parameters associated with the rotation of the Earth, and the fact that between the fifth and fifteenth centuries, the period that we consider, almost none of these observations were made scientifically, since they usually appear in narrative texts, be they chronicles or annals. Our purpose is to make a compilation of these phenomena, trying to shed light on some of the most controversial observations after examining them in their historical context. We will examine European sources, but, occasionally, we will also consider reports from other parts of the world to make comparisons, when necessary. [ABSTRACT FROM AUTHOR]

Since its founding, Centaurus has served as a journal of reference for the history of astronomy. To celebrate this tradition, our first virtual issue assembles ten articles from our archives and one article that is in currently in press. Together, these articles show off the range of contributions in history of astronomy that have appeared in the pages of Centaurus from the 1950s onward. Articles cover a number of contexts that have strongly informed the development of mathematical astronomy and celestial physics in Europe: from ancient (Babylonian, Greek, Roman) to medieval (Arabic, Jewish, Latin) to early‐modern. A second important theme of this issue arises naturally from these contributions placed side‐by‐side: the history of European astronomical development is one of trade, circulation, appropriation, innovation and continuity, over great differences in culture and geography. [ABSTRACT FROM AUTHOR]

Among the works by Jean des Murs that have yet to be printed are his Canones tabularum Alfonsii , which he wrote in 1339 during his last attested stay at the Collège de Sorbonne. One element of particular interest in this concisely worded text is Jean's discussion of the length of the solar year, which was the first to take into consideration the consequences of the Alfonsine precession model for the length of the tropical year. Another is his approach to finding the time of true syzygy, which can be compared with some of his earlier writings on the same topic. Taken together, these writings reveal something about Jean's development as an astronomer over time, as he adjusted his preferred method of syzygy computation in reaction to empirical data. The article concludes with a look at the chapters devoted to the calculation of eclipse times and magnitudes, which turn out to be strongly influenced by John of Genoa's Canones eclipsium , written in 1332. [ABSTRACT FROM AUTHOR]

A set of student activities is presented based on astronomical observations made by ancient and medieval astronomers. The activities are implemented using freeware planetarium software and can be accessed by astronomy educators or anyone with an interest in the history of astronomy. The use of planetarium software offers a unique possibility to reproduce landmark observations in a fun and interactive way. [ABSTRACT FROM AUTHOR]

Corsuno’s treatise on the astrolabe (Barcelona, 1378) is extant in only one Hebrew manuscript preserved at the Bayerische Staatsbibliothek in Munich. This text, which is a set of instructions for constructing an astrolabe, is, according to Corsuno’s words, a translation of the Arabic treatise that he devoted to the same topic in Seville in 1376, which is not extant. The text presents original traits in relation to contemporary astrolabe sources and certainly in relation to Hebrew sources on the astrolabe. The article analyses Corsuno’s contribution to the field of astrolabe literature in Hebrew and presents the Hebrew edition and translation of his astrolabe text (the Hebrew edition available in the Hebrew appendices, in the online version of JHA). [ABSTRACT FROM AUTHOR]

This article examines an unstudied set of astronomical tables for the meridian of Cambridge, also known as the Opus secundum, which the English theologian and astronomer John Holbroke, Master of Peterhouse, composed in 1433. These tables stand out from other late medieval adaptations of the Alfonsine Tables in using a different set of parameters for planetary mean motions, which Holbroke can be shown to have derived from a tropical year of 36514-1132 or 365.24¯ days. Implicit in this year length was a 33-year cycle of repeating solar longitudes and equinox times, which has left traces in other astronomical tables from fifteenth-century England. An analysis of the manuscript evidence suggests that Holbroke owed his value for the “true length of the year” to a certain Richard Monke, capellanus de Anglia, who employed this parameter and the corresponding 33-year cycle in an attempt to construct a perfect and perpetual solar calendar, leading to his Kalendarium verum anni mundi of 1434. [ABSTRACT FROM AUTHOR]

The author criticizes the arguments presented by Neil Postman in the book "Crazy Talk, Stupid Talk." Topics discussed include things that Postman says about astrology, reason that many of those who criticize astrology do so, and the problems with the causal model and suggestions about the noncausal basis for astrological judgments.

Copyright of Constantine's Letters / Konštantínove Listy is the property of Institute for Research of Constantine & Methodius's Cultural Heritage and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Historía da Sociedade e da Cultura is the property of Revista de Historia da Sociedade e da Cultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article examines the specific traits of the decline of astrology in a scholarly context at the end of the seventeenth century, specifically considering the case of the University of Valencia as a robust center of astrological learning during the sixteenth and seventeenth centuries. The tradition of these university professors of astrology is compared to the attitude of the 'novatores,' significant scholars at the beginning of the eighteenth century known for their insistence on introducing the 'new science' to Spain. This article ultimately analyzes to what extent there is evidence that the hostile attitude of the novatores of Valencia towards astrology could have led to its decline in the University. [ABSTRACT FROM AUTHOR]

This study seeks to determine the extent of the patronage of the science of the stars ('ilm al-nuǧūm) at the court of the eighth Ottoman sultan Bāyezīd II (r. 886/1481- 918/1512). Throughout the medieval and early modern Islamicate world munaǧǧims (astronomer-astrologers) offered rulers their expertise in calculating heavenly configurations and interpreting them with a view to predicting future events; here the Ottoman polity is no exception. In the case of Bāyezīd II, however, the sheer number of munaǧǧims employed and texts and instruments commissioned by or dedicated to the sultan unequivocally singles him out and makes it possible to further argue that his deliberate attempt to personally study and cultivate the science of the stars was inextricably related to the broader political, ideological, and cultural agendas at the time. The first part of the article provides statistical evidence on the exceptional nature of Bāyezīd's patronization of the science of the stars based upon a number of archival documents, taqwīms (annual almanac-prognostications) and related texts presented to the sultan. Here a number of key munaǧǧims active at his court will also be introduced. The second part focuses upon Bāyezīd's own learned interests and intellectual aspirations, and examine the celestial inquiries of the sultan in light of a few curious archival reports, textual evidence from surviving manuscripts, and testimonies of his contemporaries. [ABSTRACT FROM AUTHOR]

The third and last of Abraham Ibn Ezra's three Hebrew treatises on the astrolabe was composed in Béziers in 1148. In 1144 or soon after, a Christian scholar, Rudolph of Bruges, composed a Latin work the construction of an astrolabe, referring to an observation he had made in the same city on April 24 of that year. The present article assembles the evidence that Béziers was a place where Jews and Christians were working together to write about and practice the science of the stars; it also proposes the identification of a certain 'John David' as a patron of this activity. [ABSTRACT FROM AUTHOR]

Isaac Israeli (early fourteenth century) is best known for Yesod ʿolam(Berlin, 1846-1848), a treatise on astronomy and chronology. Here our focus is on his astronomical tables, mainly those in his unpublished Šaʿar ha-šamayim, which have not been studied previously. We present an analysis of some of these tables, preserved in various manuscripts, and find that they are largely dependent on similar sets of tables available at the time in Spain. Of special interest is that in the headings of a few of his tables he introduces an unusual term for 'table,' ʿarugah, whereas in others we find the usual luaḥ.Moreover, he uses ḥalaqimor 'parts' (that is, 1/1080 of an hour) in astronomical and geographical contexts having nothing to do with the treatment of the Hebrew calendar where they commonly occur. In Yesod ʿolamIsaac mentions Isaac ben Sid, an astronomer who worked under the patronage of Alfonso X of Castile (d. 1284) and one of the authors of the Castilian Alfonsine Tables (of which only the canons or instructions survive). Unfortunately, we have not found any trace of those tables in Isaac's tables. On the other hand, we have found evidence that, for the compilation of some of his tables, Isaac used the Toledan Tables (arranged for the Hijra calendar). [ABSTRACT FROM AUTHOR]

A characteristic hallmark of medieval astronomy is the replacement of Ptolemy's linear precession with so-called models of trepidation, which were deemed necessary to account for divergences between parameters and data transmitted by Ptolemy and those found by later astronomers. Trepidation is commonly thought to have dominated European astronomy from the twelfth century to the Copernican Revolution, meeting its demise only in the last quarter of the sixteenth century thanks to the observational work of Tycho Brahe. The present article seeks to challenge this picture by surveying the extent to which Latin astronomers of the late Middle Ages expressed criticisms of trepidation models or rejected their validity in favour of linear precession. It argues that a readiness to abandon trepidation was more widespread prior to Brahe than hitherto realized and that it frequently came as the result of empirical considerations. This critical attitude towards trepidation reached an early culmination point with the work of Agostino Ricci ( De motu octavae spherae, 1513), who demonstrated the theory's redundancy with a penetrating analysis of the role of observational error in Ptolemy's Almagest. [ABSTRACT FROM AUTHOR]

It is a long time since the last comprehensive compilation of meteoric observations from medieval European sources was published. Since then, the advances in information technology, search engines and, above all, the emergence and development of the Internet have facilitated the access to and search for these records for scholars, making their work easier and even avoiding the need to go to libraries that keep the documents. In this paper, we have significantly enlarged the list of reports of medieval European meteoric events, using mainly the current classical sources and also other local documents previously not considered by the authors that have dealt with this issue. [ABSTRACT FROM AUTHOR]

Research on medieval European astrolabes has hitherto been somewhat haphazard. Most pieces are unsigned and undated, many difficult to assign to a specific region. Some early ones cannot be understood without reference to the Islamic tradition from which they derive. What are perhaps the most important pieces from a historical point of view--the earliest-known astrolabe, from 10th-century Catalonia, and the astrolabe made by the leading astronomer of 15th-century Europe, Regiomontanus,-were declared fakes or suspicious before they could be studied seriously. A detailed study of groups of related instruments, for example, those with Hebrew inscriptions, is a most welcome contribution. A survey of the clearly-identifiable astrolabes made in medieval England (or France or Italy) has never been undertaken; maybe this list might encourage somebody willing to learn the language of instruments to undertake such a task. [ABSTRACT FROM AUTHOR]

The astrolabe of Petrus Raimundi, made in Barcelona in 1375, occupies a significant position in the set of medieval Spanish astrolabes with Latin inscriptions, as it is the only one signed and dated that has survived to the present day. A full description and study of the astrolabe is presented in the context of the support given to the manufacturing of scientific instruments by King Peter IV of Aragon. Although the astronomical and time reckoning features of the astrolabe are fully detailed, special attention is given to its artistic and decorative features. The relationships between Petrus Raimundi's astrolabe and those manufactured in al-Andalus, the region under Islamic rule within the Iberian Peninsula in the Middle Ages, are highlighted, as well as the links with astrolabe production in other European Christian kingdoms. The role played by astrolabes in medicine is considered and first steps are taken towards discovering the identity of Petrus Raimundi. [ABSTRACT FROM AUTHOR]

In the medieval Islamic world, many scholars engaged in astronomy composed books on astrolabe, especially treatises on how to operate it (called "Treatises on the Operation of the Astrolabe") such as Book of the Astrolabe (Kitāb al-Asṭurlāb) by Kūshyār ibn Labbān (fl. second half of the tenth century CE); however, most of them had similar contents. One might ask why these scholars sought to write their own treatises of this kind, even though they differed little from existing works on the subject? To answer this question, I compare Kūshyār's Book of the Astrolabe (Kitāb al-Asṭurlāb) and Athīr al-Dīn al-Abharī's (d. 1262 or 1265) Treatise on Knowing the Astrolabe (Risāla fī maʿrifat al-Asṭurlāb), which was written under the strong influence of Kūshyār's Book: a comparison between them reveals that they presupposed the use of their own astrolabes. This analysis shows that many Arabic treatises on the operation of the astrolabe had their novelty at least guaranteed by the uniqueness of a specific astrolabe presupposed by each author. [ABSTRACT FROM AUTHOR]

This article is dedicated to the obscure Computus of Magister Cunestabulus (England, 1175), which offers a unique spotlight on the way the twelfth-century 'Renaissance' in mathematical astronomy impacted the Latin computistical tradition. Armed with an unusually broad array of sources newly translated from Arabic, among them Ptolemy's Almagest, Cunestabulus applied his advanced knowledge in the service of traditional Latin learning and established Church doctrine, defending the non-existence of Antipodeans in the southern hemisphere as well as the astronomical foundations of the ecclesiastical computus. His intricate explanation of the error underlying the Julian calendar, which was based on the Arabic theory of the 'access and recess of the eighth sphere', makes for a technically sophisticated and conceptually intriguing case of Graeco-Arabic science being used for apologetic ends in twelfth-century Latin writing. [ABSTRACT FROM AUTHOR]

The Liber floridus is a medieval encyclopaedia, authored by a certain Lambert, Canon of Saint-Omer. The work was finished in 1121 and deals with a multitude of different topics, from religion and history to geography and astronomy. The Gent manuscript, which is the autograph, contains 287 folios of parchment. Detailed descriptions were given by Delisle (1906) and Derolez (1998). The topics of Lambert's astronomy are divers. The movement of the sun and moon, the calendar, and the constellations are described. Several planetary diagrams are given, followed by astrological drawings as well as various geographical, meteorological, and astronomical remarks. These astronomical texts and figures so far have not been the object of detailed studies. In this paper an overview on the astronomical topics of the manuscript is given, several pages are described in more detail, and possible sources are discussed. [ABSTRACT FROM AUTHOR]

The Īlkhānī zīj compiled by Naṣīr al-Dīn al-Ṭūsī and his colleagues in the first period of the astronomical activities (the 1260s and early 1270s) in the Maragha observatory includes a star table collecting important observations of Islamic astronomers from the early ninth century through the third quarter of the thirteenth century, including the Mumtaḥan astronomers, Ibn al-A‘lam, Ibn Yūnus, as well as the Maragha astronomers themselves. This table gives the ecliptical coordinates of 18 bright stars in comparison with Ptolemy’s corresponding values. This medieval bright star table is especially interesting for two reasons: first, it provides reliable evidence for the examination of the accuracy of the observations made and the instruments employed (notably, an armillary sphere) in the Maragha observatory. Second, it facilitates a comparative study of the accuracy of stellar observations in medieval Middle Eastern astronomy in the period in question. We have obtained the result that the Maragha astronomers observed more accurate star longitudes than did their predecessors, while for the latitudes, all Islamic observers appear to have gained about the same degree of accuracy. We also discuss two delicate matters raised by this table: first, the problem of the use of the two different values for the rate of precession by the Maragha astronomers in order to convert earlier star longitudes to the epoch of the Īlkhānī zīj (1°/66 years for Ptolemy’s longitudes and 1°/70 years for those measured by their Islamic predecessors); second, the change in the star latitudes essentially related to the various values measured by Ptolemy and the Islamic astronomers represented side-by-side in it. Finally, we briefly discuss a small celestial globe designed by the son of Mu’ayyad al-Dīn al-‘Urḍī, the instrument-maker of the Maragha observatory. [ABSTRACT FROM AUTHOR]

This paper analyses a kinematic model for the solar motion by Quṭb al-Dīn al-Shīrāzī, a thirteenth-century Iranian astronomer at the Marāgha observatory in northwestern Iran. The purpose of this model is to account for the continuous decrease of the obliquity of the ecliptic and the solar eccentricity since the time of Ptolemy. Shīrāzī puts forward different versions of the model in his three major cosmographical works. In the final version, in his Tuḥfa, the mean ecliptic is defined by an eccentric of fixed mean eccentricity and a mean obliquity fixed with respect to the celestial equator, and the center of the epicycle, which is inclined to the eccentric, moves on the eccentric with an annual period. By an additional slow motion of the sun on the epicycle, the true eccentricity of the solar deferent, defined by the annual motion of the sun, and the sun's extreme declination from the equator change, accounting for the reduction of the eccentricity and the obliquity of the ecliptic since the time of Ptolemy. [ABSTRACT FROM AUTHOR]

The lack of astronomical observations from medieval and early modern Spanish sources is a constant in the records of solar eclipses, meteors, and other celestial phenomena. This may be partially explained by the absence of a documentary corpus similar to the Monumenta Germaniae Historica, for example, that scholars may use for conducting a systematic search of such records; the problems increase by the presence of four different vernacular languages in the peninsula: Castilian, Catalan, Basque, and Galician, together with some other minority languages, to which Latin and Arabic must be added for historical research purposes. Currently, scientific literature records few medieval Spanish astronomical accounts, and most of them are contained in wider Arab surveys or they come from the best-known annals and chronicles. Our article intends to fill this gap partially in the issue of meteoritic activity. We present a survey of meteors, bolides, and meteor storms observed in Spain in the eighth–fourteenth centuries. Most of them have not been previously published and come from local or minor sources, but for the sake of completeness, we have included some records already mentioned by other authors. [ABSTRACT FROM AUTHOR]

There is a unique cluster of four medieval round churches, linked by a simple geometry, on Bornholm Island in the Baltic Sea. Why so many and why so close together? Immediate simple answers are "Just by chance" and "For no reason." Why are the churches round? "Defense." This essay proposes another hypothesis for this unique situation: the churches are astronomical observatories, meant to solve a scientific problem (Is the Earth really spherical?) and a practical problem (How far is it to sail west to the Orient?). The capacity and desire to find answers, together with other practical needs related to astronomy, can better explain these round churches' special architecture. The geometry that connects them fits the ideal pattern with an angular accuracy of 1 minute of a degree. The round churches may be the earliest astronomical observatories in Christian Europe; other hypotheses have been shown to be untenable. Their location provides for a good method to estimate the Earth's extent in the east-west direction, seemingly the earliest such measurements. [ABSTRACT FROM AUTHOR]