H. Shimodaira

Observations of TeV Gamma-Ray Flares from Markarian 501with the Telescope Array Prototype

We will report the observations of TeV gamma ray flares from Markarian 501 using Telescope Array Prototype. The observation were carried out continuously from the end of March to the end of July in 1997. The energy spectrum, and the time variation of the gamma ray intensities are shown. The intensity has been changed by the order of magnitude in this period and the possible quasi periodic oscillation of 12.7days were discovered.We report the observations of TeV gamma-ray flares from Markarian 501 using the Telescope Array Prototype. The observations were carried out continuously from the end of March to the end of July of 1997. The energy spectrum and the time variation of the gamma-ray intensities are shown. The intensity has been changed by an order of magnitude in this period, and the possible quasi-periodic oscillation of 12.7 days were discovered.

Measurement of ultra-high energy cosmic rays by telescope array (ta)

The Telescope Array (TA) is a large scale ground experiment in Utah, USA for the measurement of extensive air showers from the ultra-high energy cosmic rays. Its construction is completed in March, 2008 and the data taking started.

Energy spectrum of TeV gamma rays from Mrk 501 obtained by stereoscopic analysis

Abstract We have observed flares of TeV-gamma rays from Mrk501 in 1997 using three telescopes of the Utah Seven Telescope Array at Dugway, Utah. Determination of the energy spectrum from such Active Galactic Nuclei (AGN) is very important, because the gamma-ray spectrum is expected to steepen around 10 TeV from objects like Mrk501 by the interaction of the infrared photons. We have developed the method to estimate energies of the gamma rays by stereoscopic analysis using multiple telescopes. The differential index of the energy spectrum obtained is well expressed by −2.5 between 700 GeV and 3 TeV. This spectrum seems to become steeper above several TeV.