1,736 research outputs found
High zenith angle observations of PKS 2155-304 with the MAGIC telescope
The high frequency peaked BL Lac PKS 2155-304 with a redshift z=0.116 was
discovered 1997 in the VHE range by the University of Durham Mark 6 gamma-ray
telescope in Australia with a flux corresponding to approx. 0.2 times the Crab
Nebula flux. It was later observed and detected with high significance by the
Southern observatories CANGAROO and H.E.S.S. establishing this source as the
best studied Southern TeV blazar. Detection from the Northern hemisphere was
very difficult due to challenging observation conditions under large zenith
angles. In July 2006, the H.E.S.S. collaboration reported an extraordinary
outburst of VHE gamma-emission. During the outburst, the VHE gamma-ray emission
was found to be variable on the time scales of minutes and at a mean flux of
approx. 7 times the flux observed from the Crab Nebula. The MAGIC collaboration
operates a 17m imaging air Cherenkov Telescope at La Palma (Northern
Hemisphere). Follow up observations of the extraordinary outburst have been
triggered in a Target of Opportunity program by an alert from the H.E.S.S.
collaboration. The measured spectrum and light curve are presented.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200
The drive system of the Major Atmospheric Gamma-ray Imaging Cherenkov Telescope
The MAGIC telescope is an imaging atmospheric Cherenkov telescope, designed
to observe very high energy gamma-rays while achieving a low energy threshold.
One of the key science goals is fast follow-up of the enigmatic and short lived
gamma-ray bursts. The drive system for the telescope has to meet two basic
demands: (1) During normal observations, the 72-ton telescope has to be
positioned accurately, and has to track a given sky position with high
precision at a typical rotational speed in the order of one revolution per day.
(2) For successfully observing GRB prompt emission and afterglows, it has to be
powerful enough to position to an arbitrary point on the sky within a few ten
seconds and commence normal tracking immediately thereafter. To meet these
requirements, the implementation and realization of the drive system relies
strongly on standard industry components to ensure robustness and reliability.
In this paper, we describe the mechanical setup, the drive control and the
calibration of the pointing, as well as present measurements of the accuracy of
the system. We show that the drive system is mechanically able to operate the
motors with an accuracy even better than the feedback values from the axes. In
the context of future projects, envisaging telescope arrays comprising about
100 individual instruments, the robustness and scalability of the concept is
emphasized.Comment: 15 pages, 12 (10) figures, submitted to Astroparticle Physics, a high
resolution version of the paper (particularly fig. 1) is available at
http://publications.mppmu.mpg.de/2008/MPP-2008-101/FullText.pd
Experimental oak wilt control in Missouri
A joint report by the Central States Forest Experiment Station, Forest Service, U.S. Department of Agriculture and the Missouri Agricultural Experiment Station.Digitized 2007 AES.Includes bibliographical references (page [12])
EQUILIBRIUM OF CHILDREN PRACTISING JUDO
INTRODUCTION Human body equilibrium is the index of one's health, physical development, fitness and athletic mastery level. Coordinational abilities of children aged 4-5 in maintaining statodynamic stability have been studied when solving equilibrium motor tasks ( P. Perrin, 1989; V. N. Boloban, 1990; K. Bretz, R. J. Kaske, 1994; A.U. Kholtobina, 1994, et al.) . METHODOLOGY Measurements have been made by means of ADAMtype equipment complex (Software: lngchicurbüro - Dr. K.Bretz, 1992). Different methods of solving equilibrium motor tasks by children have been determined. Their stabilograms consist of such individual parameters as: amplitude, frequency of vibration, duration of test task performance, special location in time function (on isoline, above or below it ) , and in “stabilograph-subject” coordinate system. RESULTS Spectral Fourier-analysis of stabilograms demonstrates that body stability is generally determined by vibrations having the frequencies 0.5-1.5 Hz. In the frequencies above 2-3 Hz, children subjects do not yet possess voluntary motions to regulate body postures. Coordination indices of children's body orthograde position demonstrate necessity of special training to provide body equilibrium. Developed didactical means, methods and control elements provide efficient formation of statodynamic stability skill. Stabilogram indices allow to determine coordinational abilities in children and forecast development of their voluntary motions in the structure of professional orientation
A compact and light-weight refractive telescope for the observation of extensive air showers
A general purpose instrument for imaging of Cherenkov light or fluorescence
light emitted by extensive air showers is presented. Its refractive optics
allows for a compact and light-weight design with a wide field-of-view of
12{\deg}. The optical system features a 0.5 m diameter Fresnel lens and a
camera with 61 pixels composed of Winston cones and large-sized 6x6 mm photo
sensors. As photo sensors, semi conductor light sensors (SiPMs) are utilized.
The camera provides a high photon detection efficiency together with robust
operation. The enclosed optics permit operation in regions of harsh
environmental conditions. The low price of the telescope allows the production
of a large number of telescopes and the application of the instrument in
various projects, such as FAMOUS for the Pierre Auger Observatory, HAWC's Eye
for HAWC or IceAct for IceCube. In this paper the novel design of this
telescope and first measurements are presented.Comment: Submitted to JINST, second (minor) revisio
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