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Studies of Direct Cerenkov Emission with VERITAS |
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Conference Proceedings
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Written by Stephanie Wissel for the VERITAS Collaboration
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Tuesday, 10 July 2007 |
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Contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007 astro-ph/0709.4455 Ground-based composition measurements of high-energy cosmic rays can be significantly improved by using the direct Cherenkov method. This technique targets the Cherenkov light produced by the primary particle prior to its production of an extensive air shower. With the appropriate time and angular resolution, the direct Cherenkov photons can be separated from those produced in the extensiveair shower. By utilizing the 0.15 degree angular and 2 nanosecond timing resolution of the very high energy gamma-ray telescope system, VERITAS, the charge and energy of cosmic rays at TeV energies can be identified on an event-by-event basis. Results from a preliminary search for direct Cherenkov events are discussed. |
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Last Updated ( Thursday, 29 November 2007 )
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Observations of the high-frequency-peaked BL Lac object 1ES 1218 +30.4 with VERITAS |
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Conference Proceedings
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Written by P. Fortin for the VERITAS Collaboration
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Monday, 09 July 2007 |
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Contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007 arXiv:0709.3657 The VERITAS collaboration has observed the high-frequency-peaked BL Lac object 1ES 1218+304 using an array of several imaging Cherenkov telescopes located at the Fred Lawrence Whipple Observatory in Southern Arizona. A gamma-ray signal was detected with high significance for the observations taken during several months in the 2006-2007 observing season. Here we present the detection of 1ES 1218+304 in very-high-energy gamma rays. |
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Last Updated ( Thursday, 29 November 2007 )
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Observations of the Crab Nebula and Pulsar with VERITAS |
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Conference Proceedings
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Written by O. Celik and the VERITAS Collaboration
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Friday, 06 July 2007 |
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Contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007
Observations of the Crab Nebula have proven to be the best tool to calibrate and to characterize the performance of a Cherenkov telescope. Scientifically, it is interesting to measure the energy spectrum of the Crab Nebula close to the inverse-Compton peak where a deviation is expected from the power law seen at energies above 300 GeV. Additionally, it is important to search for pulsed emission from the Crab Pulsar at energies beyond the 10 GeV upper limit of the EGRET pulsar detection. Since current models predict a cut-off in pulsed emission between 10 and 100 GeV, measurements at energies close to this range may help to discriminate between them. We observed the Crab extensively in the 2006-2007 season during the VERITAS 2- and 3-telescope commissioning phases. Using this data set we reconstructed a preliminary energy spectrum of the signal from the Crab Nebula. We also measured the optical pulsed signal to validate our GPS time-stamping and barycentering techniques and obtained an upper limit for the pulsed emission at gamma-ray energies. |
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Last Updated ( Monday, 15 October 2007 )
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Observations of the Crab Nebula with the Whipple 10m Telescope |
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Conference Proceedings
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Written by J. Grube for the VERITAS Collaboration
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Friday, 06 July 2007 |
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Contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007 arXiv:0709.4300 Due to the strong and steady TeV gamma-ray emission from the Crab Nebula supernova remnant, its measured flux and energy spectrum can be used to verify the calibration and data reduction methods applied to IACT data acquired over many observing seasons. This gives us confidence in the results obtained on variable TeV sources observed over the same period and in relating the sensitivity of new instruments to historical datasets. Here we present the results of an analysis of 65.3 hours of good quality data taken on the Crab Nebula between October 2000 and March 2006 with the Whipple 10m telescope. The total exposure resulted in a 46 sigma signal with 11886 selected excess events. The energy spectrum was best fit by a power law of the form dN/dE = (3.19 +/- 0.07_stat) x 10^-11 (E/TeV)^(-2.64 +/- 0.03_stat) cm^-2/s/TeV in the energy range 0.49--8 TeV. The systematic uncertainty in the flux was estimated to be 30%, with a systematic error of 0.2 in the photon index. A reasonable agreement is shown for a fit to a constant flux over the 6 years. |
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Observations of the Unidentified TeV γ-Ray Source TeV J2032+4130 with the Whipple Observatory |
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Science Publications
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Written by Konopelko, A. et. al.
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Sunday, 01 April 2007 |
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The Astrophysical Journal, Volume 658, p. 1062 arXiv:astro-ph/0611730 Abstract: We report on observations of the sky region around the unidentified TeV γ-ray source (TeV J2032+4130) carried out with the Whipple Observatory 10 m atmospheric Cherenkov telescope for a total of 65.5 hrs between 2003 and 2005. The standard two-dimensional analysis developed by the Whipple collaboration for a stand-alone telescope reveals an excess in the field of view at a pre-trials significance level of 6.1σ. The measured position of this excess is α2000 = 20h 32m 27s , δ2000 = 41◦ 39 17. The estimated integral flux for this γ-ray source is about 8% of the Crab-Nebula flux. The data are consistent with a point-like source. Here we present a detailed description of the standard two-dimensional analysis tech- nique used for the analysis of data taken with the Whipple Observatory 10 m telescope and the results for the TeV J2032+4130 campaign. We include a short discussion of the physical mechanisms that may be responsible for the observed γ-ray emission, based on possible association with known astrophysical objects, in particular Cygnus OB2. |
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Last Updated ( Thursday, 11 September 2008 )
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