The blazar Markarian 421 is one of the brightest TeV gamma-ray sources of the northern sky. The authors aimed to measure the physical parameters of the emitting region of the blazar jet during active ...states. They performed a dense monitoring of the source in VHE with single-dish Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC-I). MAGIC-I, and also collected complementary data in soft X-rays and optical-UV bands; then, they modeled the spectral energy distributions derived from simultaneous multi-wavelength data within the synchrotron self-Compton (SSC) framework. The source showed intense and prolonged gamma -ray activity during the whole period, with integral fluxes seldom below the level of the Crab Nebula, and up to 3.6 times this value. Eight datasets of simultaneous optical-UV, soft X-ray and MAGIC-I VHE data were obtained during different outburst phases. The data constrain the physical parameters of the jet, once the spectral energy distributions obtained are interpreted within the framework of a single-zone SSC leptonic model.
The W51 complex hosts the supernova remnant W51C which is known to interact with the molecular clouds in the star forming region W51B. In addition, a possible pulsar wind nebula CXO J192318.5+140305 ...was found likely associated with the supernova remnant. Gamma-ray emission from this region was discovered by Fermi/LAT (between 0.2 and 50 GeV) and H.E.S.S. (>1 TeV). The aim is to determine the morphology of the very-high-energy gamma-ray emission of W51 and measure its spectral properties. The researches detect an extended emission of very-high-energy gamma rays, with a significance of 11 standard deviations. They extend the spectrum from the highest Fermi/LAT energies to ...5 TeV and find that it follows a single power law with an index of 2.58 ... 0.07stat ... 0.22syst. The main part of the emission coincides with the shocked cloud region, while we find a feature extending towards the pulsar wind nebula. (ProQuest: ... denotes formulae/symbols omitted.)
The authors study the non-thermal jet emission of the BL Lac object B3 2247+381 during a high optical state. The MAGIC telescopes observed the source during 13 nights between Sep 30, 2010 and Oct 30, ...2010, collecting a total of 14.2 h of good quality very high energy (VHE) gamma -ray data. Simultaneous multiwavelength data was obtained with X-ray observations by the Swift satellite and optical R-band observations at the KVA-telescope. They also use high energy gamma -ray data from the Fermi satellite. The BL Lac object B3 2247+381 was detected, for the first time, at VHE gamma -rays at a statistical significance of 5.6 sigma . A soft VHE spectrum with a photon index of -3.2 +mn 0.6 was determined. No significant short term flux variations were found. They model the spectral energy distribution using a one-zone SSC-model, which can successfully describe their data.
The CLUE experiment operating with 4 telescopes in La Palma Alexandreas, D; Bartoli, B; Bastieri, D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Volume:
409, Issue:
1-3
Journal Article
Peer reviewed
The CLUE experiment has started operation with four of the nine telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the ...same site as the HEGRA experiment. In winter 1997 we started taking data with the telescopes pointing directly at the moon. A description of the telescopes and the performance of the detector are given.
The CLUE trigger: a VME based two level trigger for VHE experiments Alexandreas, D.; Bartoli, B.; Bastieri, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Volume:
409, Issue:
1-3
Journal Article
Peer reviewed
We describe a trigger architecture developed for shower selection in the CLUE Cherenkov telescopes. The selection is made first in each telescope of the array looking at the low resolution images ...produced by fast electronics, than requiring temporal coincidence between units. Big effort has been put to simplify the programming of trigger configurations to help the user to switch easily between different observational and calibration requests.
Status report on CLUE Alexandreas, D; Bartoli, B; Bastieri, D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1995, Volume:
360, Issue:
1-2
Journal Article
Peer reviewed
The CLUE experiment uses a new cosmic ray detector array planned to operate for the next decade. It utilises a MWPC chambers sensitive to UV, to image Cherenkov radiation produced in cosmic ray ...showers. This approach is unique in that the instrument is insensitive to skylight backgrounds, has a threshold similar to that of visible Cherenkov experiments but a longer duty cycle. These features make possible a class of interesting cosmic ray physics experiments.
The CLUE experiment has started operation with two of the ten telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the same site as the HEGRA experiment. A description of the telescopes is given and some data on the tests performed are presented.
A method to measure the γ-ray content in VHE cosmic ray showers
Nuclear instruments and methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment/Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1991
Journal Article
Neural networks have proved to be versatile and robust for particle separation in many experiments related to particle astrophysics. We apply these techniques to separate gamma rays from hadrons for ...the MAGIC Čerenkov Telescope. Two types of neural network architectures have been used for the classification task: one is the MultiLayer Perceptron (MLP) based on supervised learning, and the other is the Self-Organising Tree Algorithm (SOTA), which is based on unsupervised learning. We propose a new architecture by combining these two neural networks types to yield better and faster classification results for our classification problem.
The CLUE experiment, located in La Palma island at 2200 m a.s.l., is an array of 3×3 telescope, detecting the UV (190 – 230
nm) Čerenkov light produced by atmospheric showers. Since atmospheric ...absorption in the UV range is higher than in the visible range, CLUE cannot apply existing algorithms normally used in IACT experiments to determine primary cosmic ray direction. In this paper we present a new method developed by CLUE. The algorithm performances were evaluated using simulated showers. Using the new technique, preliminary results of last two years observational campaigns on the
Crab Nebula and on
Markarian 421 are presented, showing a clear signal on both sources. The CLUE experiment collected also data with the telescopes aiming directly at the Moon: we expect improvements also on the
Moon Shadow measurement adopting the new method.
With its diameter of 17m, the MAGIC telescope is the largest Cherenkov detector for gamma ray astrophysics. It is sensitive to photons above an energy of 30 GeV. MAGIC started operations in October ...2003 and is currently taking data. This report summarizes its main characteristics, its first results and its potential for physics.
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