Browsing by Subject "x-ray"
Now showing items 1-20 of 39
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A mini-survey of ultracool dwarfs at 4.9 ghz
(EDP Sciences, 2008-06-04)Context. A selection of ultracool dwarfs are known to be radio active, with both gyrosynchrotron emission and the electron cyclotron maser instability being given as likely emission mechanisms. Aims. We explore whether ... -
A multiwavelength view of the tev blazar markarian 421: correlated variability, flaring, and spectral evolution
(IOP Publishing, 2005-09-01)We report results from an intensive multiwavelength monitoring campaign on the TeV blazar Mrk 421 over the period of 2003 - 2004. The source was observed simultaneously at TeV energies with the Whipple 10 m telescope and ... -
A search for pulsations from geminga above 100 gev with veritas
(IOP Publishing, 2015-02-09)We present the results of 71.6 hr of observations of the Geminga pulsar (PSR J0633+1746) with the VERITAS very-high-energy gamma-ray telescope array. Data taken with VERITAS between 2007 November and 2013 February were ... -
A survey of unidentified egret sources at very high energies
(IOP Publishing, 2005-05-10)The Whipple Observatory 10 m γ-ray telescope has been used to survey the error boxes of EGRET unidentified sources in an attempt to find counterparts at energies of 350 GeV and above. Twenty-one unidentified sources ... -
A three-year multi-wavelength study of the very-high-energy γ-ray blazar 1es 0229+200
(IOP Publishing, 2014-01-21)The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma similar to 2.5), very-high-energy (VHE; E > 100 GeV) emitting gamma-ray blazar. VHE measurements ... -
Bf eridani: a cataclysmic variable with a massive white dwarf and an evolved secondary
(Oxford University Press (OUP), 2008-05-01)We present high- and medium-resolution spectroscopic observations of the cataclysmic variable BF Eridani (BF Eri) during its low and bright states. The orbital period of this system was found to be 0.270881(3) d. The ... -
Constraints on cosmic rays, magnetic fields, and dark matter from gamma-ray observations of the coma cluster of galaxies with veritas andfermi
(IOP Publishing, 2012-09-11)Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may ... -
Constraints on the very high energy emission from bl lacertae objects
(IOP Publishing, 2004-03-01)We present results from observations of 29 BL Lacertae objects, taken with the Whipple Observatory 10 m gamma-ray telescope between 1995 and 2000. The observed objects are mostly at low redshift (z<0.2), but observations ... -
Dark spot, spiral waves and the sw sextantis behaviour: it is all about ux ursae majoris
(Oxford University Press (OUP), 2010-10-12)We present an analysis of time-resolved, medium-resolution optical spectroscopic observations of UX Ursae Majoris (UX UMa) in the blue (3920-5250 A) and red (6100-7200 A) wavelength ranges that were obtained in 1999 April ... -
Deep optical observations of the -ray pulsar psr j0007+7303 in the cta 1 supernova remnant
(Oxford University Press (OUP), 2013-01-29)The Fermi Large Area Telescope discovered the time signature of a radio-silent pulsar coincident with RX J0007.0+7302, a plerion-like X-ray source at the centre of the CTA 1 supernova remnant. The inferred timing parameters ... -
Detection of t[clc]e[/clc]v gamma rays from the bl lacertae object 1es 1959+650 with the whipple 10 meter telescope
(IOP Publishing, 2003-01-20)We present the first strong detection of very high energy gamma-rays from the close (z=0.048) X-ray-selected BL Lacertae object 1ES 1959+650. Observations were made with the Whipple 10 m telescope on Mount Hopkins, Arizona, ... -
Discovery of spectral variability of markarian 421 at t[clc]e[/clc]v energies
(IOP Publishing, 2002-08-10)The detection of spectral variability of the gamma-ray blazar Mrk 421 at TeV energies is reported. Observations with the Whipple Observatory 10 m gamma-ray telescope taken in 2000/2001 revealed exceptionally strong and ... -
Discovery of tev gamma-ray emission from cta 1 by veritas
(IOP Publishing, 2013-01-23)We report the discovery of TeV gamma-ray emission coincident with the shell-type radio supernova remnant (SNR) CTA 1 using the VERITAS gamma-ray observatory. The source, VER J0006+729, was detected as a 6.5 standard deviation ... -
Firstnustarobservations of mrk 501 within a radio to tev multi-instrument campaign
(IOP Publishing, 2015-10-09)We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 2013 April 1 and August 10, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. ... -
Insights into the high-energy γ-ray emission of markarian 501 from extensive multifrequency observations in thefermiera
(IOP Publishing, 2011-01-12)We report on the gamma-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) gamma-ray spectrum of Mrk 501 can be well described by a single ... -
Investigating broadband variability of the tev blazar 1es 1959+650
(IOP Publishing, 2014-12-03)We summarize broadband observations of the TeV-emitting blazar 1ES 1959+650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift Ultraviolet and Optical ... -
Multiband variability studies and novel broadband sed modeling of mrk 501 in 2009
(EDP Sciences, 2017-07-01)Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, ... -
Multiwavelength observations of markarian 421 in 2005-2006
(IOP Publishing, 2009-03-31)Since 2005 September, the Whipple 10 m Gamma-ray Telescope has been operated primarily as a blazar monitor. The five northern hemisphere blazars that have already been detected at the Whipple Observatory, Markarian 421 ... -
Multiwavelength observations of mrk 501 in 2008
(EDP Sciences, 2014-12-17)Context. Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (&gt;100 GeV, hereafter VHE). Mrk 501 is one of the brightest blazars at TeV energies and ... -
Multiwavelength observations of the blazar markarian 421 in 2002 december and 2003 january
(IOP Publishing, 2006-04-20)We report on a multiwavelength campaign on the TeV gamma-ray blazar Mrk 421 performed during 2002 December and 2003 January. These target of opportunity observations were initiated by the detection of X-ray and TeV gamma-ray ...