Related papers: Multi-wavelength Observations of VHE BL Lac Object…

Discovery of very high-energy gamma-ray emission from the LBL object BL Lacertae

The low-frequency peaked BL Lac (LBL) object BL Lacertae was observed with the MAGIC telescope from 2005 August to December (22.2 hr), and from 2006 July to September (26.0 hr). A very high energy (VHE) gamma-ray signal was discovered with…

Astrophysics · Physics 2007-09-17 MAGIC Collaboration , M. Hayashida , K. Berger , E. Lindfors , V. Vitale , R. Wagner , E. Lorenz

Optical and Radio variability of the Northern VHE gamma-ray emitting BL Lac objects

We compare the variability properties of very high energy gamma-ray emitting BL Lac objects in the optical and radio bands. We use the variability information to distinguish multiple emission components in the jet, to be used as a guidance…

High Energy Astrophysical Phenomena · Physics 2016-10-05 E. J. Lindfors , T. Hovatta , K. Nilsson , R. Reinthal , V. Fallah Ramazani , V. Pavlidou , W. Max-Moerbeck , J. Richards , A. Berdyugin , L. Takalo , A. Sillanpää , A. C. S. Readhead

Probing the origin of VHE emission from M 87 with MWL observations in 2010

The large majority of extragalactic very high energy (VHE; E>100 GeV) sources belongs to the class of active galactic nuclei (AGN), in particular the BL Lac sub-class. AGNs are characterized by an extremely bright and compact emission…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-15 Martin Raue , Lukasz Stawarz , Daniel Mazin , Pierre Colin , Michelle Hui , Matthias Beilicke , Craig Walker

Time-Dependent Modeling of the Sub-Hour Spectral Evolution During the 2013 Outburst of Mrk 421

In April 2013, the TeV blazar Markarian~421 underwent one of its most powerful emission outbursts to date. An extensive multi-instrument campaign featuring MAGIC, VERITAS, and \textit{NuSTAR} provided comprehensive very-high-energy (VHE; $E…

High Energy Astrophysical Phenomena · Physics 2026-03-06 MAGIC Collaboration , K. Abe , S. Abe , J. Abhir , A. Abhishek , A. Aguasca-Cabot , I. Agudo , T. Aniello , S. Ansoldi , L. A. Antonelli , A. Arbet Engels , C. Arcaro , T. T. H. Arnesen , A. Babić , C. Bakshi , U. Barres de Almeida , J. A. Barrio , L. Barrios-Jiménez , I. Batković , J. Baxter , J. Becerra González , W. Bednarek , E. Bernardini , J. Bernete , A. Berti , C. Bigongiari , A. Biland , O. Blanch , G. Bonnoli , Ž Bošnjak , E. Bronzini , I. Burelli , A. Campoy-Ordaz , A. Carosi , R. Carosi , M. Carretero-Castrillo , A. J. Castro-Tirado , D. Cerasole , G. Ceribella , Y. Chai , A. Cifuentes , J. L. Contreras , J. Cortina , S. Covino , F. D'Ammando , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , R. de Menezes , J. Delgado , C. Delgado Mendez , F. Di Pierro , R. Di Tria , L. Di Venere , A. Dinesh , D. Dominis Prester , A. Donini , D. Dorner , M. Doro , L. Eisenberger , D. Elsaesser , J. Escudero , L. Fariña , L. Foffano , L. Font , S. Fröse , Y. Fukazawa , R. J. García López , S. García Soto , M. Garczarczyk , S. Gasparyan , J. G. Giesbrecht Paiva , N. Giglietto , F. Giordano , P. Gliwny , T. Gradetzke , R. Grau , D. Green , J. G. Green , P. Günther , A. Hahn , T. Hassan , L. Heckmann , J. Herrera Llorente , D. Hrupec , D. Israyelyan , J. Jahanvi , I. Jiménez Martínez , J. Jiménez Quiles , J. Jormanainen , S. Kankkunen , T. Kayanoki , J. Konrad , P. M. Kouch , G. Koziol , H. Kubo , J. Kushida , M. Laínez , A. Lamastra , E. Lindfors , S. Lombardi , F. Longo , M. López-Moya , A. López-Oramas , S. Loporchio , L. Lulić , E. Lyard , P. Majumdar , M. Makariev , M. Mallamaci , G. Maneva , M. Manganaro , S. Mangano , K. Mannheim , S. Marchesi , M. Mariotti , M. Martínez , P. Maruševec , S. Menchiari , J. Méndez Gallego , S. Menon , D. Miceli , J. M. Miranda , R. Mirzoyan , M. Molero González , E. Molina , H. A. Mondal , A. Moralejo , C. Nanci , A. Negro , V. Neustroev , L. Nickel , M. Nievas Rosillo , C. Nigro , L. Nikolić , S. Nozaki , A. Okumura , J. Otero-Santos , S. Paiano , D. Paneque , R. Paoletti , J. M. Paredes , M. Peresano , M. Persic , M. Pihet , G. Pirola , F. Podobnik , P. G. Prada Moroni , E. Prandini , W. Rhode , M. Ribó , J. Rico , A. Roy , N. Sahakyan , F. G. Saturni , K. Schmitz , F. Schmuckermaier , T. Schweizer , A. Sciaccaluga , G. Silvestri , A. Simongini , J. Sitarek , V. Sliusar , D. Sobczynska , A. Stamerra , J. Strišković , D. Strom , M. Strzys , Y. Suda , H. Tajima , R. Takeishi , F. Tavecchio , T. Terzić , M. Teshima , A. Tutone , S. Ubach , J. van Scherpenberg , M. Vazquez Acosta , S. Ventura , G. Verna , I. Viale , A. Vigliano , C. F. Vigorito , E. Visentin , V. Vitale , I. Vovk , R. Walter , F. Wersig , M. Will , T. Yamamoto , P. K. H. Yeung , M. Petropoulou , M. Polkas , A. Mastichiadis

The June 2008 flare of Markarian 421 from optical to TeV energies

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 $\gamma$-ray signal…

Astrophysics · Physics 2012-08-27 The Agile Collaboration , Webt Collaboration , Magic Collaboration , Veritas Collaboration , I. Donnarumma

The Discovery of gamma-Ray Emission From The Blazar RGB J0710+591

The high-frequency-peaked BL Lacertae object RGB J0710+591 was observed in the very high-energy (VHE; E > 100 GeV) wave band by the VERITAS array of atmospheric Cherenkov telescopes. The observations, taken between 2008 December and 2009…

High Energy Astrophysical Phenomena · Physics 2015-05-18 V. A. Acciari , E. Aliu , T. Arlen , T. Aune , M. Bautista , M. Beilicke , W. Benbow , M. Böttcher , D. Boltuch , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , L. Ciupik , W. Cui , R. Dickherber , C. Duke , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , K. Gibbs , G. H. Gillanders , S. Godambe , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , 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 , A. Lamerato , S. LeBohec , G. Maier , S. McArthur , A. McCann , M. McCutcheon , P. Moriarty , R. Mukherjee , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , D. Petry , A. Pichel , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , P. Roustazadeh , M. Schroedter , G. H. Sembroski , G. Demet Senturk , A. W. Smith , D. Steele , S. P. Swordy , G. Tešić , M. Theiling , S. Thibadeau , A. Varlotta , V. V. Vassiliev , S. Vincent , R. G. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , S. Wissel , M. Wood , B. Zitzer , M. Ackermann , M. Ajello , E. Antolini , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , K. Bechtol , R. Bellazzini , B. Berenji , R. D. Blandford , E. D. Bloom , E. Bonamente , A. W. Borgland , A. Bouvier , J. Bregeon , M. Brigida , P. Bruel , R. Buehler , S. Buson , G. A. Caliandro , R. A. Cameron , P. A. Caraveo , S. Carrigan , J. M. Casandjian , E. Cavazzuti , C. Cecchi , Ö. Çelik , E. Charles , A. Chekhtman , C. C. Cheung , J. Chiang , S. Ciprini , R. Claus , J. Cohen-Tanugi , J. Conrad , C. D. Dermer , F. de Palma , E. do Couto e Silva , P. S. Drell , R. Dubois , D. Dumora , C. Farnier , C. Favuzzi , S. J. Fegan , P. Fortin , M. Frailis , Y. Fukazawa , S. Funk , P. Fusco , F. Gargano , D. Gasparrini , N. Gehrels , S. Germani , B. Giebels , N. Giglietto , F. Giordano , M. Giroletti , T. Glanzman , G. Godfrey , I. A. Grenier , J. E. Grove , S. Guiriec , E. Hays , D. Horan , R. E. Hughes , G. Jóhannesson , A. S. Johnson , W. N. Johnson , T. Kamae , H. Katagiri , J. Kataoka , J. Knödlseder , M. Kuss , J. Lande , L. Latronico , S. -H. Lee , M. Llena Garde , F. Longo , F. Loparco , B. Lott , M. N. Lovellette , P. Lubrano , A. Makeev , M. N. Mazziotta , P. F. Michelson , W. Mitthumsiri , T. Mizuno , A. A. Moiseev , C. Monte , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Murgia , P. L. Nolan , J. P. Norris , E. Nuss , M. Ohno , T. Ohsugi , N. Omodei , E. Orlando , J. F. Ormes , D. Paneque , J. H. Panetta , V. Pelassa , M. Pepe , M. Pesce-Rollins , F. Piron , T. A. Porter , S. Rainò , R. Rando , M. Razzano , A. Reimer , O. Reimer , J. Ripken , A. Y. Rodriguez , M. Roth , H. F. -W. Sadrozinski , D. Sanchez , A. Sander , J. D. Scargle , C. Sgrò , E. J. Siskind , P. D. Smith , G. Spandre , P. Spinelli , M. S. Strickman , D. J. Suson , H. Takahashi , T. Tanaka , J. B. Thayer , J. G. Thayer , D. J. Thompson , L. Tibaldo , D. F. Torres , G. Tosti , A. Tramacere , T. L. Usher , V. Vasileiou , N. Vilchez , V. Vitale , A. P. Waite , P. Wang , B. L. Winer , K. S. Wood , Z. Yang , T. Ylinen , M. Ziegler

Detection of Vhe Gamma-Rays from MRK 501 with the Cat Imaging Telescope

The CAT imaging telescope on the site on the former solar plant Themis has been observing gamma-rays from Mrk501 above 220 GeV in March and April 1997. This source is shown to be highly variable and the light curve is presented. The…

Astrophysics · Physics 2007-05-23 A. Barrau , R. Bazer-Bachi , H. Cabot , L. M. Chounet , G. Debiais , B. Degrange , J. P. Dezalay , A. Djannati-Atai , D. Dumora , P. Espigat , B. Fabre , P. Fleury , G. Fontaine , R. George , C. Ghesquiere , P. Goret , C. Gouiffes , I. A. Grenier , L. Iacoucci , S. Le Bohec , I. Mallet , C. Meynadier , F. Munz , T. A. Palfrey , E. Pare , Y. Pons , M. Punch , J. Quebert , K. Ragan , C. Renault , M. Rivoal , L. Rob , P. Schovanek , D. Smith , J. P. Tavernet , J. Vrana

Multiwavelength spectral and temporal analysis of VHE Blazar 1ES 1959+650: Tracing emission mechanisms across flux states

The high-synchrotron-peaked BL Lac object 1ES\,1959+650 exhibited pronounced activity between MJD~60310 -- 60603, including a very high energy (VHE) detection reported by LHAASO. To investigate the underlying emission mechanisms, we…

High Energy Astrophysical Phenomena · Physics 2025-12-24 Peer Anjum , Athar A. Dar , Zahir Shah , Bari Maqbool , Ranjeev Misra

Correlation between the TeV and X-ray emission in high--energy peaked BL Lac objects

We discuss the correlation between the evolution of the TeV emission and X-ray radiation observed in high-energy peaked BL Lac objects. We describe such a correlation by a simple power law. In the first part of this work we present…

Astrophysics · Physics 2009-11-10 K. Katarzynski , G. Ghisellini , F. Tavecchio , L. Maraschi , G. Fossati , A. Mastichiadis

Complex Spectral Variability from Intensive Multi-wavelength Monitoring of Mrk421 in 1998

We conducted a multi-frequency campaign for the TeV blazar Mrk~421 in 1998 April. The campaign started from a pronounced high amplitude flare recorded by SAX and Whipple; ASCA observation started three days later. In the X-ray data, we…

Astrophysics · Physics 2009-10-31 T. Takahashi , J. Kataoka , G. Madejski , J. Mattox , C. M. Urry , S. Wagner , F. Aharonian , M. Catanese , L. Chiappetti , P. Coppi , B. Degrange , G. Fossati , H. Kubo , H. Krawczynski , F. Makino , H. Marshall , L. Maraschi , F. Piron , R. Remillard , F. Takahara , M. Tashiro , H. Terasranta , T. Weekes

Proton Synchrotron, an explanation for possible extended VHE gamma-ray activity of TXS 0506+056 in 2017

TXS 0506+056, a source of the extreme energy neutrino event, IceCube-170922A, was observed on 22 September 2017. The Fermi-LAT detector reported high energy (HE) $\gamma$-ray flare between 100 MeV and 100 GeV starting from 15 September 2017…

High Energy Astrophysical Phenomena · Physics 2022-12-21 Sunanda , Reetanjali Moharana , Pratik Majumdar

Gamma-ray light curve and VLBI polarization connection in Mrk 421

We present Fermi-LAT and multi-frequency, multi-epoch VLBA data for the TeV blazar Mrk421. We collected the data during a long and intensive multi-frequency campaign in 2011. We study the gamma-ray light curve, the photon index evolution…

High Energy Astrophysical Phenomena · Physics 2019-08-14 M. Giroletti , F. D'Ammando , M. Orienti , D. Paneque , R. Lico , G. Giovannini , J. L. Gómez , S. Jorstad , A. Marscher

Search for High Energy Gamma Rays from an X-ray Selected Blazar Sample

Our understanding of blazars has been greatly increased in recent years by extensive multi-wavelength observations, particularly in the radio, X-ray and gamma-ray regions. Over the past decade the Whipple 10m telescope has contributed to…

Astrophysics · Physics 2010-11-24 I. de la Calle Perez , the VERITAS Collaboration

Temporal and spectral gamma-ray properties of Mkn421 above 250 GeV from CAT observations between 1996 and 2000

The gamma-ray emission above 250 GeV from the BL Lac object Markarian 421 was observed by the CAT Cherenkov imaging telescope between December, 1996, and June, 2000. In 1998, the source produced a series of small flares, making it the…

Astrophysics · Physics 2014-10-13 F. Piron , A. Djannati-Atai , M. Punch , J. -P. Tavernet , A. Barrau , R. Bazer-Bachi , L. -M. Chounet , G. Debiais , B. Degrange , J. -P. Dezalay , P. Espigat , B. Fabre , P. Fleury , G. Fontaine , P. Goret , C. Gouiffes , B. Khelifi , I. Malet , C. Masterson , G. Mohanty , E. Nuss , C. Renault , M. Rivoal , L. Rob , S. Vorobiov

A Very High Energy Gamma-Ray Spectrum of 1ES 2344+514

The BL Lacertae (BL Lac) object 1ES 2344+514 (1ES 2344), at a redshift of 0.044, was discovered as a source of very high energy (VHE) gamma rays by the Whipple Collaboration in 1995 \citep{2344Catanese98}. This detection was recently…

Astrophysics · Physics 2008-11-26 M. Schroedter , H. M. Badran , J. H. Buckley , J. Bussons Gordo , D. A. Carter-Lewis , C. Duke , D. J. Fegan , S. F. Fegan , J. P. Finley , G. H. Gillanders , J. Grube , D. Horan , G. E. Kenny , M. Kertzman , K. Kosack , F. Krennrich , D. B. Kieda , J. Kildea , M. J. Lang , Kuen Lee , P. Moriarty , J. Quinn , M. Quinn , G. B. Power-Mooney , H. Sembroski , S. P. Wakely , V. V. Vassiliev , T. C. Weekes , J. Zweerink

Study of the Flux and Spectral Variations in the VHE Emission from the Blazar Markarian 501, with the MAGIC Telescope

The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC Telescope during May, June and July 2005. The high sensitivity of the instrument made possible the detection of the source with high significance in each of the…

Astrophysics · Physics 2009-06-23 D. Paneque

Discovery of Very High Energy Gamma-Ray Emission from the BL Lac Object H2356-309 with the H.E.S.S. Cherenkov Telescopes

The extreme synchrotron BL Lac object H2356-309, located at a redshift of z = 0.165, was observed from June to December 2004 with a total exposure of approx. 40 h live-time with the H.E.S.S. (High Energy Stereoscopic System) array of…

Astrophysics · Physics 2009-11-11 Aharonian et al.

Multiwavelength Observations of the BL Lacertae Object PKS 2155-304 with XMM-Newton

The optical-UV and X-ray instruments on-board XMM-Ndewton provide an excellent opportunity to perform simultaneous observations of violently variable objects over a broad wavelength range. The UV and X-ray bright BL Lac object PKS 2155-304…

Astrophysics · Physics 2008-11-26 Y. H. Zhang , J. M. Bai , S. N. Zhang , A. Treves , L. Maraschi , A. Celotti

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 Observations of Strong Flares From the TeV-Blazar 1ES 1959+650

Following the detection of strong TeV gamma-ray flares from the BL Lac object 1ES 1959+650 with the Whipple 10 m Cherenkov telescope on May 16 and 17, 2002, we performed intensive Target of Opportunity (ToO) radio, optical, X-ray and TeV…

Astrophysics · Physics 2008-11-26 H. Krawczynski , S. B. Hughes , D. Horan , F. Aharonian , M. F. Aller , H. Aller , P. Boltwood , J. Buckley , P. Coppi , G. Fossati , N. Goetting , J. Holder , D. Horns , O. M. Kurtanidze , A. P. Marscher , M. Nikolashvili , R. A. Remillard , A. Sadun , M. Schroeder