1,720,965 research outputs found
L'importanza di un approccio multidisciplinare coordinato nelle indagini sui monumenti dell'antichità
Full text linkAn in-depth preliminary knowledge of a cultural heritage is necessary to protect and preserve the cultural heritage itself. For this purpose, today we can use a lot of methodologies developed by scholars of different disciplines: archaeologists, historians of Art, architects, engineers, biologists, chemists, physicists. Also two other new disciplines, Archaeoastronomy and Analysis of the geometries, can complete and integrate this knowledge.
This work collects the results of the investigation on geometrical and numerical schemes and associated length units and on orientation and astronomical meaning of some artefact belonging to different eras: the hypogeal Neo-Pytagorean Basilica at Porta Maggiore in Roma and the Mithraea in Ostia Antica
New bright carbon stars found in the DFBS
No full textCarbon-rich stars (C stars) of Population II, such as CH giants, can provide direct information on the role of low-to-intermediate-mass stars of the Halo in early Galactic evolution. Moreover, accurate knowledge of the CH stellar population is a critical requirement for building up scenarios for early Galactic chemical evolution
The orientation of the Mithraea in Ostia Antica
Full text linkWe conducted an investigation on the orientations and geometrical content of the Mithraea of Ostia Antica.
A geometrical CAD study based on the most reliable plans from the Archives of the Sovrintendenza Speciale
per il Colosseo, il MNR e l’Area Archeologica di Roma – Ostia Antica, aside with the identification of geometrical
and numerical schemes and associated length units, allowed us to identify the axes of the Mithraea. Then the
orientations of the axes were measured on field by means of a professional compass with ± 0.5° uncertainty.
The distribution of these measured azimuths follows the topography of the city. On the contrary, the Decumanus,
the main street of the town, presents an indubitable orientation toward the Winter Solstice Sunset.
This was ascertained by measuring the coordinates of four significant points along the street with the help of
a palmar Trimble GPS which averages 100 measures per point.
The exceptional density of Mithraea in Ostia led us to suppose that a symbolic cosmic-solar value is to be
searched in the orientation as a whole of the town itself, founded half a millennium before the first presence
of Mithraism in Rome. The Decumanus could be considered the very holder of this symbolic value with its
orientation toward the Winter Solstice Sunset, possibly making of Ostia a very special place for Mithraicism
SiFAP: a simple sub-millisecond astronomical photometer
No full textA new fast photometer based on SiPM technology was developed at the University of Rome "La Sapienza" starting from 2009. A first prototype was successfully tested observing the Crab pulsar at the Loiano telescope of the Bologna Observatory. In this paper we illustrate the improvements we applied to our instrument, concerning new cooled commercial sensors, a new version of our custom dedicated electronics and an upgraded control timing software. Finally we report the results obtained with this instrument on December 2012 on the Crab pulsar at the Loiano telescope to show its goodness and capabilities
The Latest Version of SiFAP: Beyond Microsecond Time Scale Photometry of Variable Objects
No full textTechnical improvements of the Silicon Fast optical Astronomical Photometer (SiFAP) allow the instrumentation to integrate photons coming from the target in time windows down to 20μs. Further hardware improvement has been implemented to tag the Time of Arrival (ToA) of each single photon. In addition, a new commercial GPS unit has replaced the older commercial unit improving time resolution. The latest version of SiFAP has been calibrated to check photometric sensitivity and linearity through observations of several standard stars. SiFAP has been also successfully tested by observing the HZ/Her X-1 Binary System estimating the spin period of the pulsar (Her X-1). Our results have been then compared to data available in literature
SiFAP: A new fast astronomical photometer
Full text linkA fast photometer based on SiPM technology was developed and tested at the University of Rome “La Sapienza” and at the Bologna Observatory. In this paper we present the improvements applied to our instrument, concerning new cooled sensors, a new version of the electronics and an upgraded control timing software
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multifrequency observations of a sample of very low frequency peaked BL Lacertae objects
No full textContext. BL Lacertae objects with an extremely low value of the peak frequency (v(s) <= 10(13) Hz) of the synchrotron component (VLBL objects) are poorly known. Aims. We selected a small sample of these candidate objects on the basis of their radio/optical flux ratio to evaluate their variability, define the low energy part of their SED and obtain a reliable estimate of their v(s) through a fit with a log-parabolic law. Methods. They were the object of a ground-based observational campaign in the infrared and optical bands; data from several pointings by the Swift satellite in the UV and X-ray band were also obtained for half the sample. We complemented our data with a large number of literature data. Results. These sources showed a marked flux variability, as expected for BL Lacertae objects of the low energy peaked BL Lac objects (LBL) and intermediate BL Lac objects type; all of them have a v(s) value around 10(13) Hz, but this is low enough only for a few sources to consider them genuine VLBL objects. We report the overall properties of individual sources and discuss some aspects of this class of rare objects, which could correspond to the transition between flat spectrum radio quasars and LBLs
- …
