254 research outputs found
Optical and infrared photometry of the blazar PKS0537-441
We present a large collection of photometric data on the Blazar PKS 0537-441
in the VRIJHK bands taken in 2004-2009. At least three flare-like episodes with
months duration, and >3 mag amplitude are apparent. The spectral energy
distribution is consistent with a power law, and no indication of a thermal
component is found. We searched for short time scale variability, and an
interesting event was identified in the J band, with a duration of ~25 minutes.Comment: 10 pages, 3 figures, in press in ApJ
UVscope and its application aboard the ASTRI-Horn telescope
UVscope is an instrument, based on a multi-pixel photon detector, developed
to support experimental activities for high-energy astrophysics and cosmic ray
research. The instrument, working in single photon counting mode, is designed
to directly measure light flux in the wavelengths range 300-650~nm. The
instrument can be used in a wide field of applications where the knowledge of
the nocturnal environmental luminosity is required. Currently, one UVscope
instrument is allocated onto the external structure of the ASTRI-Horn Cherenkov
telescope devoted to the gamma-ray astronomy at very high energies. Being
co-aligned with the ASTRI-Horn camera axis, UVscope can measure the diffuse
emission of the night sky background simultaneously with the ASTRI-Horn camera,
without any interference with the main telescope data taking procedures.
UVscope is properly calibrated and it is used as an independent reference
instrument for test and diagnostic of the novel ASTRI-Horn telescope.Comment: Published (Open Access) in "Experimental Astronomy
Muon calibration of the ASTRI-Horn telescope: preliminary results
Astri-Horn is a Small-Sized Telescope (SST) for very-high energy gamma-ray
astronomy installed in Italy at the INAF "M.C. Fracastoro" observing station
(Mt. Etna, Sicily). The ASTRI-Horn telescope is characterized by a dual-mirror
optical system and a curved focal surface covered by SiPM sensors managed by a
innovative fast front-end electronics. Dedicated studies were performed to
verify the feasibility of the calibration through muons on the relatively small
size of the primary mirror (~4 m diameter), as in the case of larger Cherenkov
telescopes. A number of tests were performed using simulations of the
atmospheric showers with the CORSIKA package and of the telescope response with
a dedicated simulator. In this contribution we present a preliminary analysis
of muon events detected by ASTRI-Horn during the regular scientific data taking
performed in December 2018 and March 2019. These muon events validate the
results obtained with the simulations and definitively confirm the feasibility
of calibrating the ASTRI-Horn SST telescope with muons.Comment: Proceedings of the 36th International Cosmic Ray Conference, Madison,
Wisconsin, USA, 24 July-1 August 201
Expected performance of the ASTRI-SST-2M telescope prototype
ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is an
Italian flagship project pursued by INAF (Istituto Nazionale di Astrofisica)
strictly linked to the development of the Cherenkov Telescope Array, CTA.
Primary goal of the ASTRI program is the design and production of an end-to-end
prototype of a Small Size Telescope for the CTA sub-array devoted to the
highest gamma-ray energy region. The prototype, named ASTRI SST-2M, will be
tested on field in Italy during 2014. This telescope will be the first
Cherenkov telescope adopting the double reflection layout in a
Schwarzschild-Couder configuration with a tessellated primary mirror and a
monolithic secondary mirror. The collected light will be focused on a compact
and light-weight camera based on silicon photo-multipliers covering a 9.6 deg
full field of view. Detailed Monte Carlo simulations have been performed to
estimate the performance of the planned telescope. The results regarding its
energy threshold, sensitivity and angular resolution are shown and discussed.Comment: In Proceedings of the 33rd International Cosmic Ray Conference
(ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223
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