Results for "A. Furniss"

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The Blazar Emission Environment: Insight from Soft X-ray AbsorptionApr 30 2013Collecting experimental insight into the relativistic particle populations and emission mechanisms at work within TeV-emitting blazar jets, which are spatially unresolvable in most bands and have strong beaming factors, is a daunting task. New observational ... More
A Correlation Between Hard Gamma-ray Sources and Cosmic Voids Along the Line of SightJul 23 2014Dec 01 2014We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected ... More
On the Redshift of the Very High Energy Blazar 3C 66AFeb 12 2013As a bright gamma-ray source, 3C 66A is of great interest to the high-energy astrophysics community, having a potential for placing cosmological constraints on models for the extragalactic background light (EBL) and the processes which contribute to this ... More
VERITAS Results from Deep Exposure on the Distant FSRQ 4C +55.17Mar 05 2013We present results from a deep VERITAS exposure of the distant (z=0.89) flat-spectrum radio quasar (FSRQ) 4C +55.17. The high flux, hard index and steady emission found by Fermi LAT observations make this blazar a promising very-high-energy (VHE; E>100 ... More
On the redshift of the blazar PKS0447-439Jul 16 2012Aug 14 2012PKS0447-439 is one of the BL Lacertae objects that have been detected at very high energy. There has been a recent report of a lower limit of z>1.246 for the redshift of this blazar, challenging the current paradigm in which very high-energy gamma-rays ... More
The Firm Redshift Lower Limit of the Most Distant TeV-Detected Blazar PKS 1424+240Apr 17 2013Apr 23 2013We present the redshift lower limit of z>0.6035 for the very-high-energy (VHE; E>100 GeV) emitting blazar PKS 1424+240 (PG 1424+240). This limit is inferred from Lyman beta and gamma absorption observed in the far-ultraviolet spectra from the Hubble Space ... More
Multiwavelength campaign on the HBL PKS 2155-304 : A new insight on its spectral energy distributionFeb 10 2015Feb 17 2015The blazar PKS~2155-304 was the target of a multiwavelength campaign from June to October 2013 which widely improves our knowledge of its spectral energy distribution. This campaign involved the NuSTAR satellite (3-79 keV), the Fermi Large Area Telescope ... More
A Search for Pulsed Very High-Energy Gamma Rays from Thirteen Young Pulsars in Archival VERITAS DataApr 19 2019We conduct a search for periodic emission in the very high-energy gamma-ray band (VHE; E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hours. The set of pulsars includes many of the brightest young ... More
Search for Magnetically Broadened Cascade Emission From Blazars with VERITASJan 02 2017We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGN), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma rays from AGN interact with extragalactic background ... More
Muon Hunter: a Zooniverse projectFeb 24 2018The large datasets and often low signal-to-noise inherent to the raw data of modern astroparticle experiments calls out for increasingly sophisticated event classification techniques. Machine learning algorithms, such as neural networks, have the potential ... More
Gamma-ray Observations Under Bright Moonlight with VERITASMar 03 2017Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive photomultiplier tube (PMT) cameras. Exposure to high levels of background illumination degrades the efficiency of and potentially destroys these photo-detectors over time, so ... More
Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outburstsAug 23 2016Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June ... More
VERITAS Observations of Very High Energy Blazars and Potential for Cosmological InsightFeb 10 2015Gamma-ray blazars are among the most extreme astrophysical sources, harboring phenomena far more energetic than those attainable by terrestrial accelerators. These galaxies are understood to be active galactic nuclei that are powered by accretion onto ... More
Fermi Large Area Telescope Observations of the Active Galaxy 4C +55.17: Steady, Hard Gamma-Ray Emission and its ImplicationsJul 07 2011We report Fermi/LAT observations and broad-band spectral modeling of the radio-loud active galaxy 4C +55.17 (z=0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi/LAT data, we detect a gamma-ray continuum ... More
On the Redshifts of the BL Lac 3FGL J0909.0+2310 and its Close CompanionNov 30 2016We report on the redshift of the BL Lac object 3FGL J0909.0+2310 based on observations obtained with the OSIRIS Multi Object Spectrograph (MOS) mounted on the 10.4-m Gran Telescopio Canarias. A redshift of 0.432+/-0.002 was obtained by the identification ... More
Very High Energy outburst of Markarian 501 in May 2009Aug 04 2016The very high energy (VHE; E $>$ 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54938--54956), 2009, as part of an extensive multi-wavelength campaign from radio to VHE. Strong VHE $\gamma$-ray activity was detected on May ... More
VERITAS: Status and HighlightsNov 04 2011The VERITAS telescope array has been operating smoothly since 2007, and has detected gamma-ray emission above 100 GeV from 40 astrophysical sources. These include blazars, pulsar wind nebulae, supernova remnants, gamma-ray binary systems, a starburst ... More
Multiwavelength observations and modeling of 1ES 1959+650 in a low flux stateJul 25 2013We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation (sigma) significance in 7.6 hours of observation in a ... More
Long term observations of B2 1215+30 with VERITASOct 24 2013We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHE; E > 100 GeV) by VERITAS with a significance of $8.9\sigma$ and showed clear variability on ... More
A search for enhanced very high energy gamma-ray emission from the March 2013 Crab Nebula flareSep 23 2013Jan 08 2014In March 2013, a flaring episode from the Crab Nebula lasting ~2 weeks was detected by the Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). VERITAS provides simultaneous observations throughout this period. During the flare, ... More
Multiwavelength Observations of The TeV Binary LS I +61 303 with VERITAS, Fermi-LAT and Swift-XRT During a TeV OutburstOct 29 2013We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61 303 with the VERITAS telescope array (>200 GeV), Fermi-LAT (0.3-300 GeV), and Swift-XRT (2-10 keV). The data were taken from December 2011 through January ... More
New GTC Spectroscopic Data and a Statistical Study to Better Constrain the Redshift of the BL Lac RGB J2243+203Nov 07 2018We present new spectroscopic data of the BL Lac RGB 2243+203, and its surroundings, obtained with the OSIRIS Multi Object Spectrograph (MOS) mounted in the Gran Telescopio Canarias (GTC). The spectra of neither the BL Lac nor its host galaxy show any ... More
The Arecibo Legacy Fast ALFA Survey: III. HI Source Catalog of the Northern Virgo Cluster RegionFeb 12 2007We present the first installment of HI sources extracted from the Arecibo Legacy Fast ALFA (ALFALFA) extragalactic survey, initiated in 2005. Sources have been extracted from 3-D spectral data cubes and then examined interactively to yield global HI parameters. ... More
The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area TelescopeJan 24 2015Aug 26 2015The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic (TS) greater than 25, between 2008 ... More
Schema Validation and Evolution for Graph DatabasesFeb 18 2019Despite the maturity of commercial graph databases, little consensus has been reached so far on the standardization of data definition languages (DDLs) for property graphs (PG). The discussion on the characteristics of PG schemas is ongoing in many standardization ... More
A search of CO emission lines in blazars: the low molecular gas content of BL Lac objects compared to quasarsMay 28 2012BL Lacertae (Lac) objects that are detected at very-high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties of the extragalactic background light and the strength of the ... More
First study of Mrk 501 through the eyes of NuSTAR, VERITAS and the LIDAR-corrected eyesight of MAGICAug 20 2015The blazar Mrk 501 is among the brightest X-ray and TeV sources in the sky, and among the few sources whose spectral energy distributions can be characterized by current instruments with relatively short observations (minutes to hours). In 2013, we organized ... More
First NuSTAR Observations of Mrk 501 within a Radio to TeV Multi-Instrument CampaignSep 16 2015Sep 24 2015We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 1 April and 10 August 2013, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During the campaign, the nearby ... More
First NuSTAR observations of the BL Lac - type blazar PKS~2155-304: constraints on the jet content and distribution of radiating particlesSep 07 2016We report the first hard X-ray observations with NuSTAR of the BL Lac type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and gamma-ray data from the Fermi Large Area Telescope, obtained in April 2013 when the source was in a very ... More
First Results from NuSTAR Observations of Mkn 421Sep 17 2013Oct 03 2013Mkn 421 is a nearby active galactic nucleus dominated at all wavelengths by a very broad non-thermal continuum thought to arise from a relativistic jet seen at a small angle to the line of sight. Its spectral energy distribution peaks in the X-ray and ... More
Discovery of very-high-energy emission from RGB J2243+203 and derivation of its redshift upper limitSep 15 2017Very-high-energy (VHE; $>$ 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 21 and 24 December 2014. The VERITAS energy spectrum from this source can be fit ... More
A strong limit on the very-high-energy emission from GRB 150323AMar 03 2018On 2015 March 23, VERITAS responded to a $Swift$-BAT detection of a gamma-ray burst, with observations beginning 270 seconds after the onset of BAT emission, and only 135 seconds after the main BAT emission peak. No statistically significant signal is ... More
Gamma-ray observations of Tycho's SNR with VERITAS and FermiJan 24 2017High-energy gamma-ray emission from supernova remnants (SNRs) has provided a unique perspective for studies of Galactic cosmic-ray acceleration. Tycho's SNR is a particularly good target because it is a young, type Ia SNR that is well-studied over a wide ... More
Measurement of the Iron Spectrum in Cosmic Rays by VERITASJul 20 2018We present a new measurement of the energy spectrum of iron nuclei in cosmic rays from 20 to 500 TeV. The measurement makes use of a template-based analysis method, which, for the first time, is applied to the energy reconstruction of iron-induced air ... More
VERITAS observations of the BL Lac object TXS 0506+056Jul 12 2018On 2017 September 22, the IceCube Neutrino Observatory reported the detection of the high-energy neutrino event \icnu, of potential astrophysical origin. It was soon determined that the neutrino direction was consistent with the location of the gamma-ray ... More
Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITASJan 15 2010We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ~6% of the Crab Nebula flux, ... More
VERITAS contributions to the 35th International Cosmic Ray ConferenceSep 22 2017Compilation of papers presented by the VERITAS Collaboration at the 35th International Cosmic Ray Conference (ICRC), held July 12 through July 20, 2017 in Busan, South Korea.
HESS J1943+213: An Extreme Blazar Shining Through The Galactic PlaneJun 11 2018HESS J1943+213 is a very-high-energy (VHE; $>$100 GeV) $\gamma$-ray source in the direction of the Galactic Plane. Studies exploring the classification of the source are converging towards its identification as an extreme synchrotron BL Lac object. Here ... More
Measurement of Cosmic-ray Electrons at TeV Energies by VERITASAug 29 2018Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy and these ... More
Direct measurement of stellar angular diameters by the VERITAS Cherenkov TelescopesApr 12 2019The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. ... More
VERITAS and Fermi-LAT observations of new HAWC sourcesAug 30 2018The HAWC (High Altitude Water Cherenkov) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100~GeV) gamma-ray sources based on 507 days of observation. Among these, there are nineteen sources that are not associated ... More
Rapid Variability of Blazar 3C 279 during Flaring States in 2013-2014 with Joint Fermi-LAT, NuSTAR, Swift, and Ground-Based Multi-wavelength ObservationsFeb 16 2015Apr 02 2015We report the results of a multi-band observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The $\gamma$-ray emission of the source ... More
Very High-Energy Gamma-Ray Follow-Up Program Using Neutrino Triggers from IceCubeOct 06 2016Nov 12 2016We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole ... More
TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008Jun 06 2011Jun 09 2011We report on TeV gamma-ray observations of the blazar Mrk 421 (redshift of 0.031) with the VERITAS observatory and the Whipple 10m Cherenkov telescope. The excellent sensitivity of VERITAS allowed us to sample the TeV gamma-ray fluxes and energy spectra ... More
VERITAS Collaboration Contributions to the 34th International Cosmic Ray ConferenceOct 06 2015Compilation of papers presented by the VERITAS Collaboration at the 34th International Cosmic Ray Conference (ICRC), held July 30 through August 6, 2015 in The Hague, The Netherlands.
VERITAS Collaboration Contributions to the 32nd International Cosmic Ray ConferenceNov 10 2011Compilation of papers contributed by the VERITAS Collaboration to the 32nd International Cosmic Ray Conference, held 11-18 August 2011 in Beijing, China.
VERITAS and Multiwavelength Observations of the BL Lacertae Object 1ES 1741+196Mar 23 2016We present results from multiwavelength observations of the BL Lacertae object 1ES 1741+196, including results in the very-high-energy $\gamma$-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged ... More
Constraints on Cosmic Rays, Magnetic Fields, and Dark Matter from Gamma-Ray Observations of the Coma Cluster of Galaxies with VERITAS and FermiAug 03 2012Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated, suggesting that clusters may also be sources of very high-energy (VHE; E>100 GeV) gamma-ray emission. We report ... More
Multiwavelength observations of the blazar BL Lacertae: a new fast TeV gamma-ray flareFeb 27 2018Combined with very-long-baseline interferometry measurements, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the ... More
Constraints on Very High Energy Emission from GRB 130427AOct 20 2014Prompt emission from the very fluent and nearby (z=0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it ... More
VERITAS detection of $γ$-ray flaring activity from the BL Lac object 1ES 1727+502 during bright moonlight observationsJun 20 2015During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHE, $E>100$ GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations ... More
VERITAS Observations of the BL Lac Object PG 1553+113Nov 05 2014We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560\,GeV, is well described by a power law with a spectral index of $4.33 \pm 0.09$. ... More
VERITAS Observations of the Unusual Extragalactic Transient Swift J164449.3+573451Jul 08 2011We report on very-high-energy ($>$100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the {\it Swift} Observatory and later detected by multiple radio, optical and X-ray observatories. A total exposure ... More
A Search for Very High-Energy Gamma Rays from the Missing Link Binary Pulsar J1023+0038 with VERITASSep 06 2016The binary millisecond radio pulsar PSR J1023+0038 exhibits many characteristics similar to the gamma-ray binary system PSR B1259--63/LS 2883, making it an ideal candidate for the study of high-energy non-thermal emission. It has been the subject of multi-wavelength ... More
Science Highlights from VERITASOct 05 2015The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a ground-based array located at the Fred Lawrence Whipple Observatory in southern Arizona and is one of the world's most sensitive gamma-ray instruments at energies of 85 GeV to ... More
Investigating Broadband Variability of the TeV Blazar 1ES 1959+650Dec 02 2014We 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 UVOT, X-ray observations by the Swift X-ray Telescope (XRT), ... More
Multiwavelength Observations of the VHE Blazar 1ES 2344+514Jun 22 2011Multiwavelength observations of the high-frequency-peaked blazar 1ES2344+514 were performed from 2007 October to 2008 January. The campaign represents the first contemporaneous data on the object at very high energy (VHE, E >100 GeV) {\gamma}-ray, X-ray, ... More
Discovery of Very High-Energy Gamma-Ray Radiation from the BL Lac 1ES 0806+524Dec 04 2008The 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 the two-, and three-telescope ... More
VERITAS Observations of the Microquasar Cygnus X-3Nov 04 2013We report results from TeV gamma-ray observations of the microquasar Cygnus X-3. The observations were made with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) over a time period from 2007 June 11 to 2011 November 28. VERITAS is ... More
VERITAS contributions to the 33rd International Cosmic Ray ConferenceAug 28 2013Compilation of papers contributed by the VERITAS Collaboration to the 33rd International Cosmic Ray Conference, held 2-9 July, 2013, in Rio de Janeiro, Brazil.
VERITAS Observations of Gamma-Ray Bursts Detected by SwiftAug 31 2011Nov 26 2011We present the results of sixteen Swift-triggered GRB follow-up observations taken with the VERITAS telescope array from January, 2007 to June, 2009. The median energy threshold and response time of these observations was 260 GeV and 320 s, respectively. ... More
Multiwavelength observations of the AGN 1ES 0414+009 with VERITAS, Fermi-LAT, Swift-XRT, and MDMJun 18 2012Jun 20 2012We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between January 2008 and February 2011, resulting in 56.2 hours of good quality ... More
VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT BlazarsOct 26 2012We report on VERITAS very-high-energy (VHE; E>100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray ... More
Search for a correlation between very-high-energy gamma rays and giant radio pulses in the Crab pulsarOct 17 2012We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays ($E_{\gamma} >$ 150 GeV) and ... More
A Very High Energy $γ$-Ray Survey towards the Cygnus Region of the GalaxyMay 15 2018We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) $\gamma$-ray data taken with the VERITAS Cherenkov telescope array and over seven years of high-energy $\gamma$-ray data taken with the Fermi ... More
Gamma-ray observations of the Be/pulsar binary 1A 0535+262 during a giant X-ray outburstMar 16 2011Jul 25 2011Giant X-ray outbursts, with luminosities of about $ 10^{37}$ erg s$^{-1}$, are observed roughly every 5 years from the nearby Be/pulsar binary 1A 0535+262. In this article, we present observations of the source with VERITAS at very-high energies (VHE; ... More
A Search for Pulsations from Geminga Above 100 GeV with VERITASDec 15 2014We present the results of 71.6 hours of observations of the Geminga pulsar (PSR J0633+1746) with the VERITAS very-high-energy gamma-ray telescope array. Data taken with VERITAS between November 2007 and February 2013 were phase-folded using a Geminga ... More
Very-High-Energy $γ$-Ray Observations of the Blazar 1ES 2344+514 with VERITASAug 09 2017We present very-high-energy $\gamma$-ray observations of the BL Lac object 1ES 2344+514 taken by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) between 2007 and 2015. 1ES 2344+514 is detected with a statistical significance above ... More
Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057May 19 2009HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble known TeV binary ... More
TeV Gamma-ray Observations of The Galactic Center Ridge By VERITASFeb 26 2016The Galactic Center Ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component as well as the point sources G0.9+0.1 (a composite supernova remnant) and Sgr ... More
Detection of Extended VHE Gamma Ray Emission from G106.3+2.7 with VERITASNov 24 2009We report the detection of very-high-energy (VHE) gamma-ray emission from supernova remnant (SNR) G106.3+2.7. Observations performed in 2008 with the VERITAS atmospheric Cherenkov gamma-ray telescope resolve extended emission overlapping the elongated ... More
Discovery of TeV Gamma Ray Emission from Tycho's Supernova RemnantFeb 18 2011Apr 18 2011We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's supernova remnant. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission ... More
A Three-Year Multi-Wavelength Study of the Very High Energy Gamma-ray Blazar 1ES 0229+200Dec 23 2013The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma ~ 2.5), very-high-energy-emitting (E > 100 GeV) gamma-ray blazar. Very-high-energy measurements of this active galactic nucleus have been ... More
Highlight Talk: Recent Results from VERITASDec 29 2009VERITAS is a state-of-the-art ground-based gamma-ray observatory that operates in the very high-energy (VHE) region of 100 GeV to 50 TeV. The observatory consists of an array of four 12m-diameter imaging atmospheric Cherenkov telescopes located in southern ... More
VERITAS 2008 - 2009 monitoring of the variable gamma-ray source M87May 03 2010M87 is a nearby radio galaxy that is detected at energies ranging from radio to VHE gamma-rays. Its proximity and its jet, misaligned from our line-of-sight, enable detailed morphological studies and extensive modeling at radio, optical, and X-ray energies. ... More
Reverberation Mapping of the Kepler-Field AGN KA1858+4850Aug 29 2014KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate ... More
Discovery of Very High Energy Gamma Rays from 1ES 1440+122Aug 09 2016The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the ... More
Exceptionally bright TeV flares from the binary LS I +61$^\circ$ 303Jan 08 2016The TeV binary system LS I +61$^\circ$ 303 is known for its regular, non-thermal emission pattern which traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission ... More
Discovery of a new TeV gamma-ray source: VER J0521+211Aug 22 2013We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov telescope array. These observations were motivated by the discovery of a cluster of >30GeV photons in the first ... More
Rapid TeV Gamma-Ray Flaring of BL LacertaeNov 13 2012We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6-minute exposure, when the integral ... More
VERITAS Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C 66AJan 28 2009Dec 10 2010The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007 - 2008 in VHE (very high energy: E > 100 GeV) gamma-rays with the VERITAS stereoscopic array of imaging atmospheric Cherenkov telescopes. An excess of 1791 events ... More
Detection of Pulsed Gamma Rays Above 100 GeV from the Crab PulsarAug 18 2011We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 Gigaelectronvolts (GeV) with the VERITAS array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon ... More
Discovery of TeV Gamma-ray Emission Toward Supernova Remnant SNR G78.2+2.1May 28 2013We report the discovery of an unidentified, extended source of very-high-energy (VHE) gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hours of data taken by the VERITAS gamma-ray observatory ... More
VERITAS Observations of day-scale flaring of M87 in 2010 AprilDec 19 2011VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +- 0.16) X 10^{-11} cm^{-2} s^{-1} ... More
Observations of the unidentified gamma-ray source TeV J2032+4130 by VERITASJan 13 2014Jan 16 2014TeV J2032+4130 was the first unidentified source discovered at very high energies (VHE; E $>$ 100 GeV), with no obvious counterpart in any other wavelength. It is also the first extended source to be observed in VHE gamma rays. Following its discovery, ... More
Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopesMar 08 2016Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E>100 GeV) {\gamma}-ray sources. In this work, we ... More
VERITAS Upper Limit on the VHE Emission from the Radio Galaxy NGC 1275Nov 04 2009The recent detection by the Fermi gamma-ray space telescope of high-energy gamma-rays from the radio galaxy NGC 1275 makes the observation of the very high energy (VHE: E > 100 GeV) part of its broadband spectrum particularly interesting, especially for ... More
Discovery of High-energy and Very High Energy Gamma-ray Emission from the Blazar RBS 0413Apr 04 2012We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high-energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE gamma rays from RBS ... More
A luminous and isolated gamma-ray flare from the blazar B2 1215+30Jan 04 2017B2 1215+30 is a BL Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes, and subsequently confirmed by the VERITAS observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected ... More
Observation of Extended VHE Emission from the Supernova Remnant IC 443 with VERITASMay 20 2009We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar ... More
Multiwavelength Observations of LS I +61 303 with VERITAS, Swift and RXTEApr 28 2009We present results from a long-term monitoring campaign on the TeV binary LSI +61 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between September 2006 and February ... More
Status of the VERITAS ObservatoryOct 02 2008VERITAS, 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 astrophysical gamma-ray sources ... More
Discovery of VHE $γ$-ray emission from the SNR G54.1+0.3Apr 30 2010Jul 06 2010We report the discovery of very high energy gamma-ray emission from the direction of the SNR G54.1+0.3 using the VERITAS ground-based gamma-ray observatory. The TeV signal has an overall significance of 6.8$\sigma$ and appears point-like given the 5$^{arcminute}$ ... More
Multiwavelength Observations of the Previously Unidentified Blazar RX J0648.7+1516Oct 26 2011Nov 09 2011We report on the VERITAS discovery of very-high-energy (VHE) gamma- ray emission above 200 GeV from the high-frequency-peaked BL Lac object RXJ0648.7+1516 (GBJ0648+1516), associated with 1FGLJ0648.8+1516. The photon spectrum above 200 GeV is fit by a ... More
VERITAS observations of the BL Lac 1ES 1218+304Jan 28 2009The VERITAS collaboration reports the detection of very-high-energy (VHE) gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z=0.182. A gamma-ray signal was detected with a statistical significance of ... More
Discovery of TeV Gamma-ray Emission from CTA 1 by VERITASDec 19 2012We 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 excess over background and ... More
A Search for Brief Optical Flashes Associated with the SETI Target KIC 8462852Feb 02 2016Feb 03 2016The F-type star KIC 8462852 has recently been identified as an exceptional target for SETI (search for extraterrestrial intelligence) observations. We describe an analysis methodology for optical SETI, which we have used to analyse nine hours of serendipitous ... More
A connection between star formation activity and cosmic rays in the starburst galaxy M 82Nov 04 2009Although Galactic cosmic rays (protons and nuclei) are widely believed to be dominantly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery [1]. The active ... More
VERITAS Deep Observations of the Dwarf Spheroidal Galaxy Segue 1Feb 09 2012Jul 07 2015The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No ... More
VERITAS Discovery of >200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W ComaeAug 06 2008Aug 07 2008We 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 of gamma-ray emission was ... More