43,805 research outputs found
ASTRI for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) will be the largest ground-based
observatory operating in the very-high-energy gamma-ray (20 GeV - 300 TeV)
range. It will be based on more than one hundred telescopes, located at two
sites (northern and southern hemispheres). The energy coverage, in the southern
CTA array, will extend up to hundreds of TeV thanks to 70 small size telescopes
(SST), with primary mirrors of about 4 meters in diameter and large field of
view of the order of 9 degrees. It is proposed that one of the first sets of
precursors for the CTA SSTs array will be represented by nine ASTRI telescopes.
Their prototype, named ASTRI SST-2M, is installed in Italy. It is currently
completing the overall commissioning before entering the science verification
phase that will performed observing bright TeV sources as Crab Nebula, Mrk421
and Mrk 501 cross-checking the prototype performance with the Monte Carlo
predictions. ASTRI telescopes are characterized by a dual-mirror optical design
based on the Schwarzschild- Couder (SC) configuration. The focal-plane camera
is curved in order to fit the ideal prescription for the SC design and the
sensors are small size silicon photomultipliers read-out by a fast front-end
electronics. The telescope prototype installed in Italy, has been developed by
the Italian National Institute for Astrophysics, INAF, following an end-to-end
approach that comprises all aspects from the design, construction and
implementation of the entire hardware and software system to the final
scientific products. All parts of the system have been designed to comply with
the CTA requirements. A collaborative effort, addressed to the implementation
of the first ASTRI telescopes for the CTA southern site, is now on-going led by
INAF with the Universidade de Sao Paulo (Brazil), the North-West University
(South Africa) and the Italian National Institute for Nuclear Physics.Comment: All CTA contributions at arXiv:1709.0348
A Novel Framework for Highlight Reflectance Transformation Imaging
We propose a novel pipeline and related software tools for processing the multi-light image collections (MLICs) acquired in different application contexts to obtain shape and appearance information of captured surfaces, as well as to derive compact relightable representations of them. Our pipeline extends the popular Highlight Reflectance Transformation Imaging (H-RTI) framework, which is widely used in the Cultural Heritage domain. We support, in particular, perspective camera modeling, per-pixel interpolated light direction estimation, as well as light normalization correcting vignetting and uneven non-directional illumination. Furthermore, we propose two novel easy-to-use software tools to simplify all processing steps. The tools, in addition to support easy processing and encoding of pixel data, implement a variety of visualizations, as well as multiple reflectance-model-fitting options. Experimental tests on synthetic and real-world MLICs demonstrate the usefulness of the novel algorithmic framework and the potential benefits of the proposed tools for end-user applications.Terms: "European Union (EU)" & "Horizon 2020" / Action: H2020-EU.3.6.3. - Reflective societies - cultural heritage and European identity / Acronym: Scan4Reco / Grant number: 665091DSURF project (PRIN 2015) funded by the Italian Ministry of University and ResearchSardinian Regional Authorities under projects VIGEC and Vis&VideoLa
The camera of the fifth H.E.S.S. telescope. Part I: System description
In July 2012, as the four ground-based gamma-ray telescopes of the H.E.S.S.
(High Energy Stereoscopic System) array reached their tenth year of operation
in Khomas Highlands, Namibia, a fifth telescope took its first data as part of
the system. This new Cherenkov detector, comprising a 614.5 m^2 reflector with
a highly pixelized camera in its focal plane, improves the sensitivity of the
current array by a factor two and extends its energy domain down to a few tens
of GeV.
The present part I of the paper gives a detailed description of the fifth
H.E.S.S. telescope's camera, presenting the details of both the hardware and
the software, emphasizing the main improvements as compared to previous
H.E.S.S. camera technology.Comment: 16 pages, 13 figures, accepted for publication in NIM
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
SOXS: a wide band spectrograph to follow up transients
SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope
capable to cover the optical and NIR bands, based on the heritage of the
X-Shooter at the ESO-VLT. SOXS will be built and run by an international
consortium, carrying out rapid and longer term Target of Opportunity requests
on a variety of astronomical objects. SOXS will observe all kind of transient
and variable sources from different surveys. These will be a mixture of fast
alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term
alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by
passage of minor bodies). While the focus is on transients and variables, still
there is a wide range of other astrophysical targets and science topics that
will benefit from SOXS. The design foresees a spectrograph with a
Resolution-Slit product ~ 4500, capable of simultaneously observing over the
entire band the complete spectral range from the U- to the H-band. The limiting
magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified
from on-going imaging surveys. Light imaging capabilities in the optical band
(grizy) are also envisaged to allow for multi-band photometry of the faintest
transients. This paper outlines the status of the project, now in Final Design
Phase.Comment: 12 pages, 14 figures, to be published in SPIE Proceedings 1070
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