58 research outputs found
Fonti o monti? : Lâeziologia dellâeco e un discussa lezione di Properzio (1, 20, 50)
This article debates a line by Propertius where, in recent editions,
a modification by Heinsius (montibus) has progressively taken over the reading
of the manuscript tradition (fontibus). Besides questioning the alleged linguistic
reasons (presented by Shackleton Bailey) which would make the correction necessary, this article suggests a new argument in favour of fontibus, namely the reference to the Echo and Narcissus myth in Ovidâs Metamorphoses. Indeed, Ovid
opposes the Hellenistic aetiology of the phenomenon of echo, connected (also
by Propertius) to the abduction of Hylas by spring nymphs, with a different and more coherent aetiology, probably of his own invention, linked to the figure of
the nymph Echo, who dematerialises and remains pure sound, in this case in the
âmountainsâ. Through Ovid we can hence discover, by contrast, the reading (and
the related aetiology) he found in Propertius and rejected.Il lavoro discute un verso di Properzio in cui nelle edizioni recenti un emendamento di Heinsius (montibus) si Ăš progressivamente affermato a danno della lezione unica della tradizione manoscritta (fontibus). Oltre a mettere in dubbio le presunte ragioni linguistiche (addotte da Shackleton Bailey) che renderebbero necessaria la correzione, si propone un argomento nuovo a favore della lezione fontibus, e cioĂš il richiamo al mito di Eco e Narciso nelle Metamorfosi di Ovidio. Allâeziologia ellenistica del fenomeno dellâeco, ricondotta (anche da Properzio) alla figura di Ila rapito dalle ninfe di una fonte, Ovidio oppone infatti una diversa e piĂč âcoerenteâ eziologia, verosimilmente di sua invenzione, legata alla figura della ninfa Eco, che si smaterializza e resta puro suono percepito, in questo caso sĂŹ, tra i âmontiâ. Attraverso Ovidio si puĂČ quindi risalire, per contrasto, alla lezione (e alla connessa eziologia) che egli trovava in Properzio e rifiutava
The Brera Multi-scale Wavelet (BMW) ROSAT HRI source catalog. I: the algorithm
We present a new detection algorithm based on the wavelet transform for the
analysis of high energy astronomical images. The wavelet transform, due to its
multi-scale structure, is suited for the optimal detection of point-like as
well as extended sources, regardless of any loss of resolution with the
off-axis angle. Sources are detected as significant enhancements in the wavelet
space, after the subtraction of the non-flat components of the background.
Detection thresholds are computed through Monte Carlo simulations in order to
establish the expected number of spurious sources per field. The source
characterization is performed through a multi-source fitting in the wavelet
space. The procedure is designed to correctly deal with very crowded fields,
allowing for the simultaneous characterization of nearby sources. To obtain a
fast and reliable estimate of the source parameters and related errors, we
apply a novel decimation technique which, taking into account the correlation
properties of the wavelet transform, extracts a subset of almost independent
coefficients. We test the performance of this algorithm on synthetic fields,
analyzing with particular care the characterization of sources in poor
background situations, where the assumption of Gaussian statistics does not
hold. For these cases, where standard wavelet algorithms generally provide
underestimated errors, we infer errors through a procedure which relies on
robust basic statistics. Our algorithm is well suited for the analysis of
images taken with the new generation of X-ray instruments equipped with CCD
technology which will produce images with very low background and/or high
source density.Comment: 8 pages, 6 figures, ApJ in pres
The Swift X-ray Telescope Cluster Survey III: Cluster Catalog from 2005-2012 Archival Data
We present the Swift X-ray Cluster Survey (SWXCS) catalog obtained using
archival data from the X-ray telescope (XRT) on board the Swift satellite
acquired from 2005 to 2012, extending the first release of the SWXCS. The
catalog provides positions, soft fluxes, and, when possible, optical
counterparts for a flux-limited sample of X-ray group and cluster candidates.
We consider the fields with Galactic latitude |b| > 20 degree to avoid high HI
column densities. We discard all of the observations targeted at groups or
clusters of galaxies, as well as particular extragalactic fields not suitable
to search for faint extended sources. We finally select ~3000 useful fields
covering a total solid angle of ~400 degree^2. We identify extended source
candidates in the soft-band (0.5-2keV) images of these fields using the
software EXSdetect, which is specifically calibrated for the XRT data.
Extensive simulations are used to evaluate contamination and completeness as a
function of the source signal, allowing us to minimize the number of spurious
detections and to robustly assess the selection function. Our catalog includes
263 candidate galaxy clusters and groups down to a flux limit of 7E-15
erg/cm^2/s in the soft band, and the logN-logS is in very good agreement with
previous deep X-ray surveys. The final list of sources is cross-correlated with
published optical, X-ray, and SZ catalogs of clusters. We find that 137 sources
have been previously identified as clusters, while 126 are new detections.
Currently, we have collected redshift information for 158 sources (60% of the
entire sample). Once the optical follow-up and the X-ray spectral analysis of
the sources are complete, the SWXCS will provide a large and well-defined
catalog of groups and clusters of galaxies to perform statistical studies of
cluster properties and tests of cosmological models.Comment: 41 pages, 16 figures, 3 tables, published on ApJS in Jan 201
Premessa
Problemi attuali della ricerca sul Panegirico a Traiano di Plini
VizieR Online Data Catalog: SWXCS III. Cluster catalog from 2005-2012 Swift data (Liu+, 2015)
From the entire Swift XRT archive in the period 2005 February-2012 November, we select all the fields that can be used to build an unbiased, serendipitous X-ray cluster catalog
Copernicus Ocean State Report, issue 6
The 6th issue of the Copernicus OSR incorporates a large range of topics for the blue, white and green ocean for all European regional seas, and the global ocean over 1993â2020 with a special focus on 2020
Otis, Brooks
1nonenoneROSATI GRosati, Gianpier
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