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Full-Text Articles in Physical Sciences and Mathematics
Veritas Observations Of A Very High Energy Gamma-Ray Flare From The Blazar 3c 66a, P. T. Reynolds, Et Al
Veritas Observations Of A Very High Energy Gamma-Ray Flare From The Blazar 3c 66a, P. T. Reynolds, Et Al
Physical Sciences Publications
The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007-2008 in VHE (very high energy; E > 100 GeV) γ rays with the VERITAS stereoscopic array of imaging atmospheric Cherenkov telescopes. An excess of 1791 events is detected, corresponding to a significance of 21.2 standard deviations (σ), in these observations (32.8 hr live time). The observed integral flux above 200 GeV is 6% of the Crab Nebula's flux and shows evidence for variability on the timescale of days. The measured energy spectrum is characterized by a soft power law with photon index Γ = 4.1 ± 0.4stat ± …
The June 2008 Flare Of Markarian 421 From Optical To Tev Energies, P. T. Reynolds, Et Al
The June 2008 Flare Of Markarian 421 From Optical To Tev Energies, P. T. Reynolds, Et Al
Physical Sciences Publications
We present optical, X-ray, high-energy (30 GeV) and very high energy (100 GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high-energy γ-ray signal was detected by AGILE with between June 9 and 15, with F(E>100 MeV) = 42+14 –12 × 10–8 photons cm–2 s–1. This flaring state is brighter than the average flux observed by EGRET by a factor of ~3, but still consistent with the highest EGRET flux. In hard X-rays (20-60 keV) SuperAGILE resolved a five-day flare (June 9-15) peaking at ~55 mCrab. SuperAGILE, …
Discovery Of Very High-Energy Gamma-Ray Radiation From The Bl Lac 1es 0806+524, P. T. Reynolds, Et Al
Discovery Of Very High-Energy Gamma-Ray Radiation From The Bl Lac 1es 0806+524, P. T. Reynolds, Et Al
Physical Sciences Publications
The high-frequency-peaked BL Lacertae object 1ES 0806+524, at redshift z = 0.138, was observed in the very high energy (VHE) gamma-ray regime by VERITAS between 2006 November and 2008 April. These data encompass the two- and three-telescope commissioning phases, as well as observations with the full four-telescope array. 1ES 0806+524 is detected with a statistical significance of 6.3 standard deviations from 245 excess events. Little or no measurable variability on monthly timescales is found. The photon spectrum for the period 2007 November to 2008 April can be characterized by a power law with photon index 3.6 ± 1.0stat ± 0.3sys …
Veritas Discovery Of > 200 Gev Gamma-Ray Emission From The Intermediate-Frequency-Peaked Bl Lacertae Object W Comae, P. T. Reynolds, Et Al
Veritas Discovery Of > 200 Gev Gamma-Ray Emission From The Intermediate-Frequency-Peaked Bl Lacertae Object W Comae, P. T. Reynolds, Et Al
Physical Sciences Publications
We report the detection of very high energy γ-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z = 0.102) by VERITAS. The source was observed between 2008 January and April. A strong outburst of γ-ray emission was measured in the middle of March, lasting for only 4 days. The energy spectrum measured during the two highest flare nights is fit by a power law and is found to be very steep, with a differential photon spectral index of Γ = 3.81 ± 0.35stat± 0.34syst. The integral photon flux above 200 GeV during those two nights corresponds to …