Fonti o monti? : L’eziologia dell’eco 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 Ovid’s 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 ‘mountains’. 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 è 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 cioè il richiamo al mito di Eco e Narciso nelle Metamorfosi di Ovidio. All’eziologia ellenistica del fenomeno dell’eco, ricondotta (anche da Properzio) alla figura di Ila rapito dalle ninfe di una fonte, Ovidio oppone infatti una diversa e più ‘coerente’ eziologia, verosimilmente di sua invenzione, legata alla figura della ninfa Eco, che si smaterializza e resta puro suono percepito, in questo caso sì, tra i ‘monti’. Attraverso Ovidio si può 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 1993–2020 with a special focus on 2020

Otis, Brooks

1nonenoneROSATI GRosati, Gianpier