arXiv subjects

Juan Antonio Belmonte

Publications and source records attributed to Juan Antonio Belmonte.

12 recordsLinked to original sources

arXiv2026

The orientation of historic churches in Las Palmas de Gran Canaria and its surroundings: preliminary results

We present preliminary results of the analysis of the precise spatial orientation of colonial Christian churches located in the city of Las Palmas, capital of the island of Gran Canaria (Spain), and its surroundings. Our sample consists of 27 churches, 15 of which belong to the city proper while the rest are situated within roughly 12 km away inland. Most of these churches were constructed between the first decades after the Castilian conquest of the island, and the end of the 19th century. In our analysis we examine whether these orientations respond to calendrical coincidences, to the main features of the landscape, or whether the standard tradition was followed regarding the orientation of the churches' apses eastwards. We find that no church in the sample is oriented towards points of the horizon on which the Sun rises on the day of the patronal feasts. Furthermore, we find no correlation between the global orientation pattern and the orography of the island which, near the local prominent Guiniguada ravine, could have been an important factor at the time of the construction of the churches. What we do find is that most of the orientations fit within the solar range, mainly to the east but also with a few historic churches oriented towards the west, while less than 20% have astronomical declinations outside of this range. In the statistical analysis, the declination histogram for the sample shows a pattern where the apses of the churches point consistently to the north of due east. This might signal constructions that were oriented to the rising Sun on dates close to Easter. We briefly discuss the implications these findings may have for a future study of the rest of Gran Canaria, which includes several dozens of historic churches scattered throughout the valleys, slopes, and volcanic calderas of the island.

physics.hist-ph↗

arXiv2025

Comparing land- and skyscapes in the three main manorial-conquered lands of the Canary Islands

This work is a study of the relationship between astronomy and landscape focused on the orientation of Christian churches of the three main Manorial (Señorío) Islands of the Canary archipelago (Spain): Lanzarote, La Gomera and Fuerteventura. As a background, we have the information provided by the texts of early Christian writers, which imposed that churches should be oriented towards the east [..]. The fieldwork that supports our comparative study is based on the measurement of the precise location coordinates, axis' azimuth and angular height of the horizon for most of the churches of the three islands, which amounts to about 120 sets of measurements. For the study of the sample, we have employed various analyses, both statistical, as well as calendric and orographic. Our results show that on all the islands, the pattern of double orientations is repeated, which contemplates the canonical tradition of orienting the altars of churches within the solar range (pointing either eastward or westward). Very few cases also occur where it is possible to identify constructions whose orientation follows solstitial patterns, perhaps as imitation of aboriginal worship. But this double pattern also includes a high proportion of churches with orientations far from this range. An example is Lanzarote and Fuerteventura, both islands subjected to the same flow of the prevailing trade winds in the region, but each with its own characteristics. Another example is given by the particular orography of deep ravines of La Gomera, which determines the orientation of the temples located in those geographical accidents. In this paper we show how the combination of elements of the land- and skyscape can, with a high degree of probability, offer a satisfactory explanation to the particular orientation of these insular centres of worship, which were built during the first decades after the European conquest.

physics.hist-ph↗

arXiv2025

On the orientation of historic Christian churches of Fuerteventura: conciliating tradition, winds and topography

We present the results of an analysis of the precise spatial orientation of colonial Christian churches located in the Canary Island of Fuerteventura (Spain). Our sample consists of 48 churches, most built during the period between the Castilian conquest led by the Norman Jean de Béthencourt in the 15th century and the end of the 19th century. We examine whether the standard tradition was followed regarding the orientation of the apses of historic churches eastwards. While most of the religious constructions in the sample have their main axes oriented within the solar range, the statistical analysis also reveals the presence of two different groups of churches with different possible interpretations. For the first group, mainly composed of churches located in the central part of the island, an anomalous tendency to orientate them towards a declination of c. -14 degrees is detected. We provide some possible explanations for this, which include the date of a traditional Canarian celebration, an eventual imprint of topography, and the possibility of sunset orientations. Also, this particular value of declination is close to -16.3 degrees, the declination of Sirius during the 17th century. Therefore, we provide ethnographic data that might support an eventually controversial 'bright star' orientation. For the second group, meanwhile, we find a pattern of orientation where the apse of the churches points slightly to the north of due east. We propose this might signal constructions that were oriented to the rising Sun on dates close to Easter, one of the most important festivities of Christianity.

physics.hist-ph↗

arXiv2022

Archaeoastronomy and the alleged < >

In a recent paper in Antiquity (Darvill 2022), the author has proposed that the project of the < > phase (stage 2) of Stonehenge (c. 2600 BC) was conceived in order to represent a calendar year of 365.25 days, that is, a calendar identical in duration to the Julian calendar. The aim of the present paper is to show that this idea is totally unsubstantiated, being based as it is on a series of forced interpretations and unsupported analogies.

physics.hist-ph↗

arXiv2021

Cuando la ortodoxia no es lo más relevante: el paisaje de La Gomera y la orientación de sus iglesias

We present a study of the relationship between astronomy and landscape centered on the orientation of Christian churches of the island of La Gomera, located in the Canary Archipelago. The fieldwork consisted of measuring the precise coordinates of 38 churches, which represents almost all of the island's religious constructions, which has an area of approximately 370 km2. For each church, we measured the azimuth and the angular height of the horizon taken in the direction towards which the altar of each temple points. The data obtained were corroborated with digital terrain models frequently used in archaeoastronomical studies. Finally, for the study of the sample, various analyzes were carried out: statistical, calendarical and orographic, trying to find clues that would allow us to understand the pattern of orientations found. From this analysis, we can infer that in some places the canonical tradition of orienting Christian temples in the solar range was respected. Also, it is possible that a few constructions were oriented with imitation patterns of the aborigine cult, especially in solstitial directions. However, we find that the orientation of the majority of the churches is towards the northeast and, in the absence of a better justification, we think that reason should be sought more in the terrestrial landscape than in the celestial one. Judging by the way in which several small groups of temples are distributed, we estimate this unusual pattern of global orientations is motivated by the particular orography of the island. A significant proportion of churches seems to adapt to the characteristics of their sites, orienting themselves according to the numerous geographical features where they are located. These results allow us to conjecture that the known "abrupt nature" of La Gomera is perhaps the main reason for the particular pattern of orientations of its worship sanctuaries.

physics.hist-ph↗

arXiv2020

The development of a utopian city? Comparing land- and skyscapes in Santa Cruz de Tenerife and San Cristobal de la Laguna

We discuss the peculiar planning of the city of San Cristobal de La Laguna, in the Canary Island of Tenerife (Spain), when compared to the nearby and essentially contemporary Santa Cruz de Tenerife, which served as a maritime port of the former city. For this we review our previous study of the exact spatial orientation of twenty-one historic Christian churches currently existing in the old part of La Laguna, which we compare with the analysis of six similar buildings located in Santa Cruz, and presented here for the first time. In both cities, we take the spatial orientation of historic churches as good indicators of the original layout of the respective urban lattices. Although we find a clear orientation pattern for La Laguna, which singles out an absolute-value astronomical declination slightly below 20 degrees, pointing to a preferred date close to the July 25th feast-day of San Cristobal de Licia, in the case of Santa Cruz this trend is not followed. On the contrary, the pattern we find for Santa Cruz, within the uncertainties due to the low statistics, and apart from one equinoctial and one solstitial oriented churches, is consistent with an orographic orientation within the canonic limits of sunrise. This result highlights the uniqueness of the city of La Laguna, and supports the idea suggesting its deliberate planning in the early 16th century.

physics.hist-ph↗

arXiv2020

Urban Planning in the First Unfortified Spanish Colonial Town: The orientation of the historic churches of San Cristobal de La Laguna

The city of San Cristobal de La Laguna in the Canary Island of Tenerife (Spain) has an exceptional value due to the original conception of its plan. It is an urban system in a grid, outlined by straight streets that form squares, its layout being the first case of an unfortified colonial city with a regular plan in the overseas European expansion. It constitutes a historical example of the so-called "Town of Peace", the archetype of a city-republic in a new land that employed its own natural boundaries to delimit and defend itself. Founded in 1496, the historical centre of the old city was declared a World Heritage Site by UNESCO in 1999. We analyse the exact spatial orientation of twenty-one historic Christian churches currently existing in the old part of La Laguna which we take as a good indicator of the original layout of the urban lattice. We find a clear orientation pattern that, if correlated with the rising or setting Sun, singles out an absolute-value astronomical declination slightly below 20 degrees, which, within the margin of error of our study, might be associated with the July 25th feast-day of San Cristobal de Licia, the saint to whom the town was originally dedicated. We also discuss at some length some recent proposals which invoke somewhat far-fetched hypotheses for the planimetry of the old city and finish up with some comments on one of its outstanding features, namely its Latin-cross structure, which is apparent in the combined layout of some of its most emblematic churches.

physics.hist-ph↗

arXiv2017

On the orientation of the historic churches of Lanzarote: when human necessity dominates over canonical prescriptions

We present the analysis of the measured orientations of 30 churches of the island of Lanzarote, in the Canarian archipelago, built prior to 1810, as well as a few buildings of later times, which represent a nearly complete sample of all the island's Christian sanctuaries. Our study indicates that a definite orientation pattern was followed on the island but, unlike what is often found in most of the Christian world, it has two interpretations. On the one hand, the representative orientation to the east (or west) is present. However, the sample has also a marked orientation towards north-northeast which is, as far as we know, a pattern exclusive to Lanzarote. We discuss the reasons for this pattern and suggest that one possible explanation could be a rather prosaic one, namely, that sometimes needs of everyday life are more relevant than --and push individuals to make decisions at odds with-- religious beliefs. This work is the beginning of the first systematic archaeoastronomical study ever conducted with old churches in the Canary Islands [abridged].

physics.hist-ph↗

arXiv2016

The orientation as a signature of cultural identity: The historic churches of Lanzarote

The orientation of Christian churches is a well-known distinctive feature of their architecture. There is a general tendency to align their apses in the solar range, favoring orientations close to the east (astronomical equinox), although the alignments in the opposite direction, namely, with the apse towards the west, are not unusual. The case of the churches built in northwest Africa before the arrival of Islam is paradigmatic in this regard, and may reflect earlier traditions. The Canary Islands is the western end of this North African cultural koine, so we thought it would be relevant to study a compact set of old churches in one of the islands of the archipelago, choosing to start our project with Lanzarote. We have measured the orientation of a total of 30 churches built prior to 1810, as well as a few buildings of later times, nearly a complete sample of all the island Christian sanctuaries. The analysis of this sample indicates that a definite orientation pattern was followed on the island but, unlike the standard one often found in most of the Christian world, this prototype is twofold. On the one hand, the representative orientation to the east (or west) is present. However, the sample has also a marked orientation towards the north-northeast, which is as far as we know a pattern exclusive of Lanzarote. We analyze the reasons for this rule and suggest that one possible explanation could be a rather prosaic one, namely, that sometimes earthly needs are more relevant than religious beliefs.

physics.hist-ph↗

arXiv2012

Secondary eclipses in the CoRoT light curves: A homogeneous search based on Bayesian model selection

We aim to identify and characterize secondary eclipses in the original light curves of all published CoRoT planets using uniform detection and evaluation critetia. Our analysis is based on a Bayesian model selection between two competing models: one with and one without an eclipse signal. The search is carried out by mapping the Bayes factor in favor of the eclipse model as a function of the eclipse center time, after which the characterization of plausible eclipse candidates is done by estimating the posterior distributions of the eclipse model parameters using Markov Chain Monte Carlo. We discover statistically significant eclipse events for two planets, CoRoT-6b and CoRoT-11b, and for one brown dwarf, CoRoT-15b. We also find marginally significant eclipse events passing our plausibility criteria for CoRoT-3b, 13b, 18b, and 21b. The previously published CoRoT-1b and CoRoT-2b eclipses are also confirmed.

astro-ph.EP↗

arXiv2011

Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC

We report the detection of transit timing variations (TTVs) well in excess of one hour in the Kepler multi-planet candidate system KOI 806. This system exhibits transits consistent with three separate planets -- a Super-Earth, a Jupiter, and a Saturn -- lying very nearly in a 1:2:5 resonance, respectively. We used the Kepler public data archive and observations with the Gran Telescopio de Canarias to compile the necessary photometry. For the largest candidate planet (KOI 806.02) in this system, we detected a large transit timing variation of -103.5$\pm$6.9 minutes against previously published ephemeris. We did not obtain a strong detection of a transit color signature consistent with a planet-sized object; however, we did not detect a color difference in transit depth, either. The large TTV is consistent with theoretical predictions that exoplanets in resonance can produce large transit timing variations, particularly if the orbits are eccentric. The presence of large TTVs among the bodies in this systems indicates that KOI806 is very likely to be a planetary system. This is supported by the lack of a strong color dependence in the transit depth, which would suggest a blended eclipsing binary.

astro-ph.SR↗

arXiv2008

SYMPA, a dedicated instrument for Jovian Seismology. II. Real performance and first results

Context. Due to its great mass and its rapid formation, Jupiter has played a crucial role in shaping the Solar System. The knowledge of its internal structure would strongly constrain the solar system formation mechanism. Seismology is the most efficient way to probe directly the internal structure of giant planets. Aims. SYMPA is the first instrument dedicated to the observations of free oscillations of Jupiter. Principles and theoretical performance have been presented in paper I. This second paper describes the data processing method, the real instrumental performance and presents the first results of a Jovian observation run, lead in 2005 at Teide Observatory. Methods. SYMPA is a Fourier transform spectrometer which works at fixed optical path difference. It produces Doppler shift maps of the observed object. Velocity amplitude of Jupiter's oscillations is expected below 60 cm/s. Results Despite light technical defects, the instrument demonstrated to work correctly, being limited only by photon noise, after a careful analysis. A noise level of about 12 cm/s has been reached on a 10-night observation run, with 21 % duty cycle, which is 5 time better than previous similar observations. However, no signal from Jupiter is clearly highlighted.

astro-ph↗