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Jose Ricra

Publications and source records attributed to Jose Ricra.

3 recordsLinked to original sources

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

Archaeoastronomical study on the north-central coast of Peru

The Caral civilization developed on the north-central coast of Peru and had an occupation period between 2870 and 1970 years BC. The first studies carried out in the field of archaeoastronomy showed evidence of possible astronomical orientations in some buildings of its capital city, the Ciudad Sagrada de Caral. However, methodological issues cast doubt on these conclusions. A recent study carried out a more general statistical analysis, which covered a total of 55 architectural structures distributed in ten urban settlements that were part of this civilization, thus managing to identify topographic and astronomical orientation patterns. Based on this evidence, we propose to carry out a new study focused on the capital city, with the objective of analyzing the orientation pattern of the city, placing emphasis on the analysis of the most important religious and administrative structures in order to determine their functionality and their possible links with relevant astronomical objects. The study will include field work to measure the various structures and the subsequent statistical analysis of the data, using declination histograms, density functions and probability tests.

physics.hist-ph

Characterizing a CCD detector for astronomical purposes: OAUNI Project

This work verifies the instrumental characteristics of the CCD detector which is part of the UNI astronomical observatory. We measured the linearity of the CCD detector of the SBIG STXL6303E camera, along with the associated gain and readout noise. The linear response to the incident light of the detector is extremely linear (R2 =99.99%), its effective gain is 1.65 +/- 0.01 e-/ADU and its readout noise is 12.2 e-. These values are in agreement with the manufacturer. We confirm that this detector is extremely precise to make measurements for astronomical purposes.

astro-ph.IM