Now showing items 21-40 of 116

• #### Rotational Modulation of M/L Dwarfs due to Magnetic Spots ﻿

(2007)
We find periodic I-band variability in two ultracool dwarfs, TVLM 513-46546 and 2MASS J00361617+1821104, on either side of the M/L dwarf boundary. Both of these targets are short-period radio transients, with the detected ...
• #### A search for CO+ in planetary nebulae ﻿

(2007)
We have carried out a systematic search for the molecular ion CO+ in a sample of 8 protoplanetary and planetary nebulae in order to determine the origin of the unexpectedly strong HCO+ emission previously detected in these ...
• #### Kinematics of the Broad Line Region in M81 ﻿

(2007)
A new model is presented which explains the origin of the broad emission lines observed in the LINER/Seyfert nucleus of M81 in terms of a steady state spherically symmetric inflow, amounting to 1 x 10^-5 Msun/yr, which is ...
• #### Pulse variation of the optical emission of Crab pulsar ﻿

(2007)
The stability of the optical pulse of the Crab pulsar is analyzed based on the 1 $\mu$s resolution observations with the Russian 6-meter and William Hershel telescopes equipped with different photon-counting detectors. The ...
• #### CO abundances in a protostellar cloud: freeze-out and desorption in the envelope and outflow of L483 ﻿

(2007)
CO isotopes are able to probe the different components in protostellar clouds. These components, core, envelope and outflow have distinct physical conditions and sometimes more than one component contributes to the observed ...
• #### Very High Energy Observations of Gamma-Ray Burst Locations with the Whipple Telescope ﻿

(2007)
Gamma-ray burst (GRB) observations at very high energies (VHE, E &gt; 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and ...
• #### Very High Energy Observations of Gamma-Ray Burst Locations with the Whipple Telescope ﻿

(2007)
Gamma-ray burst (GRB) observations at very high energies (VHE, E &gt; 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and ...
• #### Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability ﻿

(2007)
(Abridged) We present a detailed analysis of week-long simultaneous observations of the blazar Mrk421 at 2-60 keV X-rays (RXTE) and TeV gamma-rays (Whipple and HEGRA) in 2001. The unprecedented quality of this dataset ...
• #### Electron beam therapy at extended SSD: a Monte Carlo investigation of output fom a Siemens Oncor linear accelerator ﻿

(2008)
Electron-beam therapy is used to treat superficial tumors at a standard 100 cm source-to-surface distance (SSD). However, certain clinical situations require the use of an extended SSD. In the present study, Monte Carlo ...
• #### Discovery of Very High-Energy Gamma-Ray Radiation from the BL Lac 1ES 0806+524 ﻿

(2008)
The high-frequency-peaked BL-Lacertae object \objectname{1ES 0806+524}, at redshift z=0.138, was observed in the very-high-energy (VHE) gamma-ray regime by VERITAS between November 2006 and April 2008. These data encompass ...
• #### Observation of gamma-ray emission from the galaxy M87 above 250 GeV with VERITAS ﻿

(2008)
The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in Active Galactic Nuclei from radio waves to TeV gamma-rays. Here we report the detection ...
• #### VERITAS Discovery of &gt;200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W Comae ﻿

(2008)
We report the detection of very high-energy gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z=0.102) by VERITAS. The source was observed between January and April 2008. A strong outburst ...
• #### Investigations of the magnetospheric plasma distribution in the vicinity of a pulsar - I Basic formulation ﻿

(2008)
The magnetospheric plasma distribution in the vicinity of a pulsar at various inclination angles is investigated using a new relativistic, parallel 3D Particle-In-Cell (PIC) code DYMPHNA3D. DYMPHNA3D uses a superposition ...
• #### Optical Observations of PSR J0205+6449 ﻿

(2008)
PSR J0205+6449 is a X-ray and radio pulsar in supernova remnant 3C 58. We report on observations of the central region of 3C 58 using the 4.2-m William Herschel Telescope with the intention of identifying the optical ...
• #### High-time Resolution Astrophysics and Pulsars ﻿

(2008)
The discovery of pulsars in 1968 heralded an era where the temporal characteristics of detectors had to be reassessed. Up to this point detector integration times would normally be measured in minutes rather seconds and ...
• #### VERITAS Observations of the gamma-Ray Binary LS I +61 303 ﻿

(2008)
LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy gamma-rays. The system was observed over several orbital cycles (between September 2006 and February ...
• #### Status of the VERITAS Observatory ﻿

(2008)
VERITAS, an Imaging Atmospheric Cherenkov Telescope (IACT) system for gammma-ray astronomy in the GeV-TeV range, has recently completed its first season of observations with a full array of four telescopes. A number of ...
• #### The June 2008 flare of Markarian 421 from optical to TeV energies ﻿

(2008)
We present optical, X-ray, high energy ($\lessapprox 30$ GeV) and very high energy ($\gtrapprox 100$ GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high energy ...
• #### A Search for Dark Matter Annihilation with the Whipple 10m Telescope ﻿

(2008)
We present observations of the dwarf galaxies Draco and Ursa Minor, the local group galaxies M32 and M33, and the globular cluster M15 conducted with the Whipple 10m gamma-ray telescope to search for the gamma-ray signature ...
• #### Improved simulation of small electron fields for external beam radiation therapy ﻿

(2009)
This paper reports on improved simulation of small electron fields from a Siemens Primus linear accelerator. Accelerator simulation was performed using the Monte Carlo user code BEAMnrc. Source and geometry parameters ...