Related papers: Recent Results from the VERITAS Collaboration

Discovery of Spectral Variability of Markarian 421 at TeV Energies

The detection of spectral variability of the gamma-ray blazar Mrk 421 at TeV energies is reported. Observations with the Whipple Observatory 10m gamma-ray telescope taken in 2000/2001 revealed exceptionally strong and long-lasting flaring…

Astrophysics · Physics 2009-11-07 F. Krennrich , I. H. Bond , S. M. Bradbury , J. H. Buckley , D. A. Carter-Lewis , W. Cui , I. de la Calle Perez , D. J. Fegan , S. J. Fegan , J. P. Finley , J. A. Gaidos , K. Gibbs , G. H. Gillanders , T. A. Hall , A. M. Hillas , J. Holder , D. Horan , M. Jordan , M. Kertzman , D. Kieda , J. Kildea , J. Knapp , K. Kosack , M. J. Lang , S. LeBohec , P. Moriarty , D. Müller , R. A. Ong , R. Pallassini , D. Petry , J. Quinn , N. W. Reay , P. T. Reynolds , H. J. Rose , G. H. Sembroski , R. Sidwell , N. Stanton , S. P. Swordy , V. V. Vassiliev , S. P. Wakely , T. C. Weekes

High Energy Astrophysics

The development of the atmospheric Cherenkov imaging technique has led to significant advances in gamma-ray detection sensitivity in the energy range from 200 GeV to 50 TeV. The Whipple Observatory 10m reflector has detected the first…

Astrophysics · Physics 2007-05-23 T. C. Weekes

H.E.S.S. Observations of strong flaring activity of Mrk421 in February 2010

The high-frequency peaked BL Lac object Mrk421 has shown a strong outburst of activity during February 2010. This high state, first detected by VERITAS on 16th of February, was followed up by H.E.S.S. during four subsequent nights at an…

High Energy Astrophysical Phenomena · Physics 2011-06-17 Martin Tluczykont

The origin of multi-TeV flares from the nearest blazar Markarian 421

Markarian 421 is a high-peaked BL Lac object and it has undergone many strong outbursts since its discovery as a TeV source in 1992. Markarian 421 has been stud- ied intensively and was observed by various Cherenkov tele- scope arrays ever…

High Energy Astrophysical Phenomena · Physics 2018-07-31 Sarira Sahu , Alberto Rosales de León , Shigehiro Nagataki , Virendra Gupta

Highlight Talk: Recent Results from VERITAS

VERITAS 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…

High Energy Astrophysical Phenomena · Physics 2009-12-31 R. A. Ong , V. A. Acciari , T. Arlen , T. Aune , M. Beilicke , W. Benbow , D. Boltuch , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , L. Ciupik , Y. C. Chow , P. Cogan , W. Cui , C. Duke , S. J. Fegan , J. P. Finley , G. Finnegan , P. Fortin , L. Fortson , A. Furniss , N. Galante , D. Gall , G. H. Gillanders , S. Godambe , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , D. Horan , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , G. Maier , S. McArthur , A. McCann , M. McCutcheon , J. Millis , P. Moriarty , A. N. Otte , D. Pandel , J. S. Perkins , A. Pichel , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , M. Schroedter , G. H. Sembroski , A. W. Smith , D. Steele , S. P. Swordy , M. Theiling , S. Thibadeau , J. A. Toner , A. Varlotta , V. V. Vassiliev , S. Vincent , R. G. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , D. A. Williams , S. Wissel , M. Wood , B. Zitzer

VERITAS Observations of LS I +61 303 in the Fermi Era

The high-mass X-ray binary system LS I +61 303 is well known as a rare example of a variable Galactic GeV and TeV gamma-ray emitter. Despite years of study, many aspects of the system remain unclear; the nature of the compact object, the…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Jamie Holder

Multi-wavelength Observations of VHE BL Lac Objects

We present multi-wavelength observations of the very high energy (VHE, E >250 GeV) gamma-ray sources Mrk 421 and Mrk 501. The VHE data presented here were taken with the Whipple Observatory 10m gamma-ray telescope. In the Mrk 421 campaign,…

Astrophysics · Physics 2019-08-14 M. Catanese

VERITAS discovery of very high energy gamma-ray emission from S3 1227+25 and multiwavelength observations

We report the detection of very high energy gamma-ray emission from the blazar S3 1227+25 (VER J1230+253) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). VERITAS observations of the source were triggered by the…

High Energy Astrophysical Phenomena · Physics 2023-06-21 Atreya Acharyya , Colin Adams , Avery Archer , Priyadarshini Bangale , Wystan Benbow , Aryeh Brill , Jodi Christiansen , Alisha Chromey , Manel Errando , Abe Falcone , Qi Feng , John Finley , Gregory Foote , Lucy Fortson , Amy Furniss , Greg Gallagher , William Hanlon , David Hanna , Olivier Hervet , Claire Hinrichs , John Hoang , Jamie Holder , Weidong Jin , Madalyn Johnson , Philip Kaaret , Mary P. Kertzman , David Kieda , Tobias Kleiner , Nikolas Korzoun , Frank Krennrich , Mark Lang , Matthew Lundy , Gernot Maier , Conor McGrath , Matthew Millard , John Millis , Connor Mooney , Patrick Moriarty , Reshmi Mukherjee , Stephan O'Brien , Rene A. Ong , Martin Pohl , Elisa Pueschel , John Quinn , Kenneth J. Ragan , Paul Reynolds , Deivid Ribeiro , Emmet Thomas Roache , Iftach Sadeh , Alberto Sadun , Lab Saha , Marcos Santander , Glenn Sembroski , Ruo Shang , Megan Splettstoesser , Anjana Talluri , James Tucci , Vladimir Vassiliev , David Williams , Sam Wong , Talvikki Hovatta , Svetlana Jorstad , Sebastian Kiehlmann , Anne Lahteenmaki , Ioannis Liodakis , Alan Marscher , Walter Max-Moerbeck , Anthony Readhead , Rodrigo Reeves , Paul S Smith , Merja Tornikoski

The 2014 TeV Gamma-ray Flare of Mrk 501 Seen with H.E.S.S.: Temporal and Spectral Constraints on Lorentz Invariance Violation

The blazar Mrk 501 (z=0.034) was observed at very-high-energy (VHE, $E\gtrsim 100$~GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data…

High Energy Astrophysical Phenomena · Physics 2019-01-17 H. E. S. S. Collaboration , : , H. Abdalla , F. Aharonian , F. Ait Benkhali , E. O. Angüner , M. Arakawa , C. Arcaro , C. Armand , M. Arrieta , M. Backes , M. Barnard , Y. Becherini , J. Becker Tjus , D. Berge , S. Bernhard , K. Bernlöhr , R. Blackwell , M. Böttcher , C. Boisson , J. Bolmont , S. Bonnefoy , P. Bordas , J. Bregeon , F. Brun , P. Brun , M. Bryan , M. Büchele , T. Bulik , T. Bylund , M. Capasso , S. Caroff , A. Carosi , S. Casanova , M. Cerruti , N. Chakraborty , S. Chandra , R. C. G. Chaves , A. Chen , S. Colafrancesco , B. Condon , I. D. Davids , C. Deil , J. Devin , P. deWilt , L. Dirson , A. Djannati-Ataï , A. Dmytriiev , A. Donath , L. O'C. Drury , J. Dyks , K. Egberts , G. Emery , J. -P. Ernenwein , S. Eschbach , S. Fegan , A. Fiasson , G. Fontaine , S. Funk , M. Füßling , S. Gabici , Y. A. Gallant , T. Garrigoux , F. Gaté , G. Giavitto , D. Glawion , J. F. Glicenstein , D. Gottschall , M. -H. Grondin , J. Hahn , M. Haupt , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , W. Hofmann , C. Hoischen , T. L. Holch , M. Holler , D. Horns , D. Huber , H. Iwasaki , A. Jacholkowska , M. Jamrozy , D. Jankowsky , F. Jankowsky , L. Jouvin , I. Jung-Richardt , M. A. Kastendieck , K. Katarzyński , M. Katsuragawa , U. Katz , D. Kerszberg , D. Khangulyan , B. Khélifi , J. King , S. Klepser , W. Kluźniak , Nu. Komin , K. Kosack , S. Krakau , M. Kraus , P. P. Krüger , G. Lamanna , J. Lau , J. Lefaucheur , A. Lemière , M. Lemoine-Goumard , J. -P. Lenain , E. Leser , T. Lohse , M. Lorentz , R. López-Coto , I. Lypova , D. Malyshev , V. Marandon , A. Marcowith , C. Mariaud , G. Guillem Martí-Devesa , R. Marx , G. Maurin , P. J. Meintjes , A. M. W. Mitchell , R. Moderski , M. Mohamed , L. Mohrmann , E. Moulin , T. Murach , S. Nakashima , M. de Naurois , H. Ndiyavala , F. Niederwanger , J. Niemiec , L. Oakes , P. O'Brien , H. Odaka , S. Ohm , M. Ostrowski , I. Oya , M. Padovani , M. Panter , R. D. Parsons , C. Perennes , P. -O. Petrucci , B. Peyaud , Q. Piel , S. Pita , V. Poireau , A. Priyana Noel , D. A. Prokhorov , H. Prokoph , G. Pühlhofer , M. Punch , A. Quirrenbach , S. Raab , R. Rauth , A. Reimer , O. Reimer , M. Renaud , F. Rieger , L. Rinchiuso , C. Romoli , G. Rowell , B. Rudak , E. Ruiz-Velasco , V. Sahakian , S. Saito , D. A. Sanchez , A. Santangelo , M. Sasaki , R. Schlickeiser , F. Schüssler , A. Schulz , U. Schwanke , S. Schwemmer , M. Seglar-Arroyo , M. Senniappan , A. S. Seyffert , N. Shafi , I. Shilon , K. Shiningayamwe , R. Simoni , A. Sinha , H. Sol , F. Spanier , A. Specovius , M. Spir-Jacob , Ł. Stawarz , R. Steenkamp , C. Stegmann , C. Steppa , I. Sushch , T. Takahashi , J. -P. Tavernet , T. Tavernier , A. M. Taylor , R. Terrier , L. Tibaldo , D. Tiziani , M. Tluczykont , C. Trichard , M. Tsirou , N. Tsuji , R. Tuffs , Y. Uchiyama , D. J. van der Walt , C. van Eldik , C. van Rensburg , B. van Soelen , G. Vasileiadis , J. Veh , C. Venter , A. Viana , P. Vincent , J. Vink , F. Voisin , H. J. Völk , T. Vuillaume , Z. Wadiasingh , S. J. Wagner , P. Wagner , R. M. Wagner , R. White , A. Wierzcholska , A. Wörnlein , R. Yang , D. Zaborov , M. Zacharias , R. Zanin , A. A. Zdziarski , A. Zech , F. Zefi , A. Ziegler , J. Zorn , N. Żywucka

Multiwavelength Observations of The TeV Binary LS I +61 303 with VERITAS, Fermi-LAT and Swift-XRT During a TeV Outburst

We 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…

High Energy Astrophysical Phenomena · Physics 2015-06-17 E. Aliu , S. Archambault , B. Behera , K. Berger , M. Beilicke , W. Benbow , R. Bird , A. Bouvier , V. Bugaev , M. Cerruti , X. Chen , L. Ciupik , M. P. Connolly , W. Cui , J. Dumm , A. Falcone , S. Federici , Q. Feng , J. P. Finley , P. Fortin , L. Fortson , A. Furniss , N. Galante , G. H. Gillanders , S. Griffin , S. T. Griffiths , J. Grube , G. Gyuk , D. Hanna , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , F. Krennrich , M. J. Lang , G. Maier , P. Majumdar , S. McArthur , A. McCann , P. Moriarty , R. Mukherjee , A. O'Faolain de Bhroithe , R. A. Ong , A. N. Otte , N. Park , J. S. Perkins , M. Pohl , A. Popkow , H. Prokoph , J. Quinn , K. Ragan , J. Rajotte , G. Ratliff , P. T. Reynolds , G. T. Richards , E. Roache , G. H. Sembroski , F. Sheidaei , C. Skole , A. W. Smith , D. Staszak , I. Telezhinsky , J. Tyler , A. Varlotta , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , A. Zajczyk , B. Zitzer

Long term observations of B2 1215+30 with VERITAS

We 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…

High Energy Astrophysical Phenomena · Physics 2015-06-17 VERITAS collaboration , E. Aliu , S. Archambault , T. Arlen , T. Aune , M. Beilicke , W. Benbow , R. Bird , A. Bouvier , J. H. Buckley , V. Bugaev , A. Cesarini , L. Ciupik , M. P. Connolly , W. Cui , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , P. Fortin , L. Fortson , A. Furniss , N. Galante , L. Gérard , G. H. Gillanders , S. Griffin , J. Grube , G. Gyuk , D. Hanna , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , P. Moriarty , R. Mukherjee , D. Nieto , A. O'Faoláin de Bhróithe , R. A. Ong , M. Orr , A. N. Otte , N. Park , J. S. Perkins , M. Pohl , A. Popkow , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , D. B. Saxon , G. H. Sembroski , C. Skole , A. W. Smith , M. Soares-Furtado , D. Staszak , I. Telezhinsky , G. Tešić , M. Theiling , A. Varlotta , V. V. Vassiliev , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , B. Zitzer , M. Böttcher , M. Fumagalli , J. Jadhav

H.E.S.S. discovery of very-high-energy gamma-ray emission of PKS 1440-389

Blazars are the most abundant class of known extragalactic very-high-energy (VHE, E>100 GeV) gamma-ray sources. However, one of the biggest difficulties in investigating their VHE emission resides in their limited number, since less than 60…

High Energy Astrophysical Phenomena · Physics 2019-08-14 H. Prokoph , Y. Becherini , M. Böttcher , C. Boisson , J. -P. Lenain , I. Sushch

VERITAS and Fermi-LAT observations of TeV gamma-ray sources from the second HAWC catalog

The HAWC observatory recently published their second source catalog with 39 very high energy gamma-ray sources based on 507 days of exposure time. Among these, there were 16 sources that are more than one degree away from any known TeV…

High Energy Astrophysical Phenomena · Physics 2019-08-15 Nahee Park

BeppoSAX Observations of the TeV Blazar Mkn 421

The blazar Mkn 421 has been observed, as part of the AO1 Core Program, five times from 2 to 7 May 1997. In the LECS+MECS energy band the spectrum shows convex curvature, well represented by a broken power--law. Flux variability (more than a…

Astrophysics · Physics 2019-08-15 G. Fossati , L. Chiappetti

An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes?

High energy observations of extreme BL Lac objects, such as 1ES 0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic…

High Energy Astrophysical Phenomena · Physics 2015-06-25 Giacomo Bonnoli , Fabrizio Tavecchio , Gabriele Ghisellini , Tullia Sbarrato

Multiwavelength Observations of the Blazar VER J0521+211 During an Elevated TeV Gamma-Ray State

We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly-binned light curve is $(8.8 \pm 0.4)…

High Energy Astrophysical Phenomena · Physics 2022-08-10 The VERITAS Collaboration , The MAGIC Collaboration

Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and $\gamma$-ray activity in 2015$-$2016

We report a characterization of the multi-band flux variability and correlations of the nearby (z=0.031) blazar Markarian 421 (Mrk 421) using data from Mets\"{a}hovi, Swift, Fermi-LAT, MAGIC, FACT and other collaborations and instruments…

High Energy Astrophysical Phenomena · Physics 2021-05-26 MAGIC Collaboration , V. A. Acciari , S. Ansoldi , L. A. Antonelli , K. Asano , A. Babić , B. Banerjee , A. Baquero , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , L. Bellizzi , E. Bernardini , M. Bernardos , A. Berti , J. Besenrieder , W. Bhattacharyya , C. Bigongiari , O. Blanch , G. Bonnoli , Ž. Bošnjak , G. Busetto , R. Carosi , G. Ceribella , M. Cerruti , Y. Chai , A. Chilingarian , S. Cikota , S. M. Colak , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , G. D'Amico , V. D'Elia , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , M. Delfino , J. Delgado , C. Delgado Mendez , D. Depaoli , T. Di Girolamo , F. Di Pierro , L. Di Venere , E. Do Souto Espiñeira , D. Dominis Prester , A. Donini , M. Doro , V. Fallah Ramazani , A. Fattorini , G. Ferrara , L. Foffano , M. V. Fonseca , L. Font , C. Fruck , S. Fukami , R. J. García López , M. Garczarczyk , S. Gasparyan , M. Gaug , N. Giglietto , F. Giordano , P. Gliwny , N. Godinović , J. G. Green , D. Green , D. Hadasch , A. Hahn , L. Heckmann , J. Herrera , J. Hoang , D. Hrupec , M. Hütten , T. Inada , S. Inoue , K. Ishio , Y. Iwamura , J. Jormanainen , L. Jouvin , Y. Kajiwara , M. Karjalainen , D. Kerszberg , Y. Kobayashi , H. Kubo , J. Kushida , A. Lamastra , D. Lelas , F. Leone , E. Lindfors , S. Lombardi , F. Longo , M. López , R. López-Coto , A. López-Oramas , S. Loporchio , B. Machado de Oliveira Fraga , C. Maggio , P. Majumdar , M. Makariev , M. Mallamaci , G. Maneva , M. Manganaro , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , S. Mender , S. Mićanović , D. Miceli , T. Miener , M. Minev , J. M. Miranda , R. Mirzoyan , E. Molina , A. Moralejo , D. Morcuende , V. Moreno , E. Moretti , P. Munar-Adrover , V. Neustroev , C. Nigro , K. Nilsson , D. Ninci , K. Nishijima , K. Noda , S. Nozaki , Y. Ohtani , T. Oka , J. Otero-Santos , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , L. Pavletić , P. Peñil , C. Perennes , M. Persic , P. G. Prada Moroni , E. Prandini , C. Priyadarshi , I. Puljak , W. Rhode , M. Ribó , J. Rico , C. Righi , A. Rugliancich , L. Saha , N. Sahakyan , T. Saito , S. Sakurai , K. Satalecka , B. Schleicher , K. Schmidt , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Spolon , A. Stamerra , D. Strom , M. Strzys , Y. Suda , T. Surić , M. Takahashi , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , N. Torres-Albà , L. Tosti , S. Truzzi , J. van Scherpenberg , G. Vanzo , M. Vazquez Acosta , S. Ventura , V. Verguilov , C. F. Vigorito , V. Vitale , I. Vovk , M. Will , D. Zarić , FACT collaboration , : , A. Arbet-Engels , D. Baack , M. Balbo , M. Beck , N. Biederbeck , A. Biland , T. Bretz , K. Bruegge , J. Buss , D. Dorner , D. Elsaesser , D. Hildebrand , R. Iotov , M. Klinger , K. Mannheim , D. Neise , A. Neronov , M. Noethe , A. Paravac , W. Rhode , B. Schleicher , V. Sliusar , F. Theissen , R. Walter , MWL Collaborators , : , J. Valverde , D. Horan , M. Giroletti , M. Perri , F. Verrecchia , C. Leto , A. C. Sadun , J. W. Moody , M. Joner , A. P. Marscher , S. G. Jorstad , A. Lähteenmäki , M. Tornikoski , V. Ramakrishnan , E. Järvelä , R. J. C. Vera , S. Righini , A. Y. Lien

Extreme blazars

The recent Cherenkov telescope observations and detections of the BL Lac objects Mkn 421, Mkn 501, 1ES 2344+514, PKS 2155--304 and possibly 1ES 1959+658 have shown that there exists a subclass of BL Lac objects emitting a substantial…

Astrophysics · Physics 2009-10-31 Gabriele Ghisellini

Highlights from VERITAS on VHE Gamma-ray Sources in our Galaxy

VERITAS is a major ground-based detector of very high energy (VHE, E > 100 GeV) gamma rays and cosmic rays. VERITAS consists of an ar- ray of four 12m-diameter atmospheric Cherenkov telescopes that has been fully operational since September…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Rene A. Ong

Optical Monitoring of PKS 2155-304 during August-September 2004 with the KVA telescope

The southern gamma-ray blazar PKS 2155-304 is one of the brightest and most intensively studied prototypes of BL Lac object. PKS 2155-304 has recently aroused the interest of Cherenkov telescope projects like HESS and MAGIC, the former…

Astrophysics · Physics 2007-05-23 S. Ciprini , E. Lindfors , K. Nilsson , L. Ostorero