Related papers: FACT -- Multi-wavelength analysis of more than 30 …

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

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

Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year time scales, which can bring additional insight on the processes responsible for its broadband emission. We observed Mrk 421 in the very high energy…

Astrophysics of Galaxies · Physics 2019-08-15 MAGIC Collaboration , M. L. Ahnen , S. Ansoldi , L. A. Antonelli , P. Antoranz , A. Babic , B. Banerjee , P. Bangale , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , E. Bernardini , B. Biasuzzi , A. Biland , O. Blanch , S. Bonnefoy , G. Bonnoli , F. Borracci , T. Bretz , S. Buson , A. Carosi , A. Chatterjee , R. Clavero , P. Colin , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , E. de Oña Wilhelmi , F. Di Pierro , A. Domínguez , D. Dominis Prester , D. Dorner , M. Doro , S. Einecke , D. Eisenacher Glawion , D. Elsaesser , A. Fernández-Barral , D. Fidalgo , M. V. Fonseca , L. Font , K. Frantzen , C. Fruck , D. Galindo , R. J. García López , M. Garczarczyk , D. Garrido Terrats , M. Gaug , P. Giammaria , N. Godinović , A. González Muñoz , D. Gora , D. Guberman , D. Hadasch , A. Hahn , Y. Hanabata , M. Hayashida , J. Herrera , J. Hose , D. Hrupec , G. Hughes , W. Idec , K. Kodani , Y. Konno , H. Kubo , J. Kushida , A. La Barbera , D. Lelas , E. Lindfors , S. Lombardi , F. Longo , M. López , R. López-Coto , P. Majumdar , M. Makariev , K. Mallot , G. Maneva , M. Manganaro , K. Mannheim , L. Maraschi , B. Marcote , M. Mariotti , M. Martínez , D. Mazin , U. Menzel , J. M. Miranda , R. Mirzoyan , A. Moralejo , E. Moretti , D. Nakajima , V. Neustroev , A. Niedzwiecki , M. Nievas Rosillo , K. Nilsson , K. Nishijima , K. Noda , L. Nogués , R. Orito , A. Overkemping , S. Paiano , J. Palacio , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , X. Paredes-Fortuny , G. Pedaletti , L. Perri , M. Persic , J. Poutanen , P. G. Prada Moroni , E. Prandini , I. Puljak , W. Rhode , M. Ribó , J. Rico , J. Rodriguez Garcia , T. Saito , K. Satalecka , C. Schultz , T. Schweizer , S. N. Shore , A. Sillanpää , J. Sitarek , I. Snidaric , D. Sobczynska , A. Stamerra , T. Steinbring , M. Strzys , L. Takalo , H. Takami , F. Tavecchio , P. Temnikov , T. Terzić , D. Tescaro , M. Teshima , J. Thaele , D. F. Torres , T. Toyama , A. Treves , V. Verguilov , I. Vovk , J. E. Ward , M. Will , M. H. Wu , R. Zanin , D. A. Blinov , W. P. Chen , N. V. Efimova , E. Forné , T. S. Grishina , T. Hovatta , B. Jordan , G. N. Kimeridze , E. N. Kopatskaya , E. Koptelova , O. M. Kurtanidze , S. O. Kurtanidze , A. Lähteenmaäki , V. M. Larionov , E. G. Larionova , L. V. Larionova , R. Ligustri , H. C. Lin , B. McBreen , D. A. Morozova , M. G. Nikolashvili , C. M. Raiteri , J. A. Ros , A. C. Sadun , L. A. Sigua , M. Tornikoski , I. S. Troitsky , M. Villata

Rapid Variability of Mrk 421 During Extreme Flaring as Seen Through the Eyes of XMM-Newton

By studying the variability of blazars across the electromagnetic spectrum, it is possible to resolve the underlying processes responsible for rapid flux increases, so-called flares. We report on an extremely bright X-ray flare in the…

High Energy Astrophysical Phenomena · Physics 2024-03-01 A. Gokus , J. Wilms , M. Kadler , D. Dorner , M. A. Nowak , A. Kreikenbohm , K. Leiter , T. Bretz , B. Schleicher , A. G. Markowitz , K. Pottschmidt , K. Mannheim , I. Kreykenbohm , M. Langejahn , F. McBride , T. Beuchert , T. Dauser , M. Kreter , J. Abhir , D. Baack , M. Balbo , A. Biland , K. Brand , J. Buss , L. Eisenberger , D. Elsaesser , P. Guenther , D. Hildebrand , M. Linhoff , A. Paravac , W. Rhode , V. Sliusar , S. Hasan , R. Walter

NICER Perspective on TeV Blazar Mrk~421: X-ray Variability and Particle Acceleration

Mrk~421 is one of the most fascinating blazars, widely studied across the electromagnetic spectrum using observations at various wavebands, from radio to the TeV gamma ray bands. We present the first detailed spectral and timing analysis of…

High Energy Astrophysical Phenomena · Physics 2025-12-10 Sangeetha Kizhakkekalam , Gopal Bhatta , Navaneeth P K , Tek P. Adhikari

Five-year Monitorings of TeV Blazars with ASCA and RXTE

We study the temporal/spectral variability of two extragalactic TeV sources, Mrk 421 and Mrk 501, based on 5-year observations with the ASCA and RXTE satellites. We found that the peak of the synchrotron emission exists just in the X-ray…

Astrophysics · Physics 2007-05-23 J. Kataoka , T. Takahashi , F. Takahara , P. G. Edwards , K. Hayashida , S. Inoue , N. Iyomoto , N. Kawai , G. M. Madejski , C. Tanihata , S. J. Wagner

Multiwavelength Observations of the Blazar Mrk 421 in December 2002 and January 2003

We report on a multiwavelength campaign on the TeV gamma-ray blazar Markarian (Mrk) 421 performed during December 2002 and January 2003. These target of opportunity observations were initiated by the detection of X-ray and TeV gamma-ray…

Astrophysics · Physics 2019-08-15 P. Rebillot , M. Aller , H. Aller , P. Boltwood , I. Jung , D. Kranich , A. Sillanpaa , A. Sadun

TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008

We 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…

High Energy Astrophysical Phenomena · Physics 2011-08-12 V. A. Acciari , E. Aliu , 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 , W. Cui , R. Dickherber , C. Duke , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , 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 , G. Maier , S. McArthur , M. McCutcheon , P. Moriarty , R. A. Ong , A. N. Otte , M. Ouellette , D. Pandel , J. S. Perkins , A. Pichel , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , A. C. Rovero , M. Schroedter , G. H. Sembroski , G. Demet Senturk , D. Steele , S. P. Swordy , 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 , A. Garson , K. Lee , A. C. Sadun , M. Carini , D. Barnaby , K. Cook , J. Maune , A. Pease , S. Smith , R. Walters , A. Berdyugin , E. Lindfors , K. Nilsson , M. Pasanen , J. Sainio , A. Sillanpaa , L. O. Takalo , C. Villforth , T. Montaruli , M. Baker , A. Lahteenmaki , M. Tornikoski , T. Hovatta , E. Nieppola , H. D. Aller , M. F. Aller

Dissecting the long-term emission behaviour of the BL Lac object Mrk 421

We report on long-term multi-wavelength monitoring of blazar Mrk 421 by the GASP-WEBT collaboration and Steward Observatory, and by the Swift and Fermi satellites. We study the source behaviour in the period 2007-2015, characterized by…

High Energy Astrophysical Phenomena · Physics 2019-08-14 M. I. Carnerero , C. M. Raiteri , M. Villata , J. A. Acosta-Pulido , V. M. Larionov , P. S. Smith , F. D'Ammando

Discovery of a new TeV gamma-ray source: VER J0521+211

We 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…

High Energy Astrophysical Phenomena · Physics 2013-10-04 VERITAS Collaboration , S. Archambault , T. Arlen , T. Aune , M. Beilicke , W. Benbow , R. Bird , A. Bouvier , J. H. Buckley , V. Bugaev , K. Byrum , A. Cesarini , L. Ciupik , M. P. Connolly , W. Cui , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , L. Fortson , A. Furniss , N. Galante , D. Gall , 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 , S. Kumar , M. J. Lang , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , J. Millis , 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 , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , D. B. Saxon , G. H. Sembroski , A. W. Smith , D. Staszak , I. Telezhinsky , 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. Bottcher , S. J. Fegan , P. Fortin , J. P. Halpern , Y. Y. Kovalev , M. L. Lister , J. Liu , A. B. Pushkarev , P. S. Smith

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

Multi-wavelength study of TeV blazar 1ES 1218+304 using gamma-ray, X-ray and optical observations

We report the multi-wavelength study for a high-synchrotron-peaked BL Lac 1ES 1218+304 using near-simultaneous data obtained during the period from January 1, 2018, to May 31, 2021 (MJD 58119-59365) from various instruments including…

High Energy Astrophysical Phenomena · Physics 2023-07-19 Rishank Diwan , Raj Prince , Aditi Agarwal , Debanjan Bose , Pratik Majumdar , Aykut Özdönmez , Sunil Chandra , Rukaiya Khatoon , Ergün Ege

X-ray Intra-day Variability of the TeV Blazar Mrk 421 with Suzaku

We present X-ray flux and spectral analyses of the three pointed Suzaku observations of the TeV high synchrotron peak blazar Mrk 421 taken throughout its complete operational duration. The observation taken on 5 May 2008 is, at 364.6…

High Energy Astrophysical Phenomena · Physics 2019-11-06 Zhongli Zhang , Alok C. Gupta , Haritma Gaur , Paul J. Wiita , Tao An , Minfeng Gu , Dan Hu , Haiguang Xu

Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

A flare from the TeV blazar Mrk 421, occurring in March 2010, was observed for 13 consecutive days from radio to very high energy (VHE, E > 100 GeV) gamma-rays with MAGIC, VERITAS, Whipple, FermiLAT, MAXI, RXTE, Swift, GASP-WEBT, and…

High Energy Astrophysical Phenomena · Physics 2015-06-16 The MAGIC Collaboration , J. Aleksić , S. Ansoldi , L. A. Antonelli , P. Antoranz , A. Babic , P. Bangale , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , E. Bernardini , B. Biasuzzi , A. Biland , O. Blanch , A. Boller , S. Bonnefoy , G. Bonnoli , F. Borracci , T. Bretz , E. Carmona , A. Carosi , P. Colin , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , P. Da Vela , F. Dazzi , A. De Angelis , G. De Caneva , B. De Lotto , E. de Oña Wilhelmi , C. Delgado Mendez , D. Dominis Prester , D. Dorner , M. Doro , S. Einecke , D. Eisenacher , D. Elsaesser , M. V. Fonseca , L. Font , K. Frantzen , C. Fruck , D. Galindo , R. J. García López , M. Garczarczyk , D. Garrido Terrats , M. Gaug , N. Godinović , A. González Muñoz , S. R. Gozzini , D. Hadasch , Y. Hanabata , M. Hayashida , J. Herrera , D. Hildebrand , J. Hose , D. Hrupec , G. Hughes , W. Idec , V. Kadenius , H. Kellermann , M. L. Knoetig , K. Kodani , Y. Konno , J. Krause , H. Kubo , J. Kushida , A. La Barbera , D. Lelas , N. Lewandowska , E. Lindfors , S. Lombardi , M. López , R. López-Coto , A. López-Oramas , E. Lorenz , I. Lozano , M. Makariev , K. Mallot , G. Maneva , N. Mankuzhiyil , K. Mannheim , L. Maraschi , B. Marcote , M. Mariotti , M. Martínez , D. Mazin , U. Menzel , J. M. Miranda , R. Mirzoyan , A. Moralejo , P. Munar-Adrover , D. Nakajima , A. Niedzwiecki , K. Nilsson , K. Nishijima , K. Noda , R. Orito , A. Overkemping , S. Paiano , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , X. Paredes-Fortuny , M. Persic , P. G. Prada Moroni , E. Prandini , I. Puljak , R. Reinthal , W. Rhode , M. Ribó , J. Rico , J. Rodriguez Garcia , S. Rügamer , T. Saito , K. Saito , K. Satalecka , V. Scalzotto , V. Scapin , C. Schultz , T. Schweizer , S. Sun , S. N. Shore , A. Sillanpää , J. Sitarek , I. Snidaric , D. Sobczynska , F. Spanier , V. Stamatescu , A. Stamerra , T. Steinbring , B. Steinke , J. Storz , M. Strzys , L. Takalo , H. Takami , F. Tavecchio , P. Temnikov , T. Terzić , D. Tescaro , M. Teshima , J. Thaele , O. Tibolla , D. F. Torres , T. Toyama , A. Treves , M. Uellenbeck , P. Vogler , R. Zanin , The VERITAS Collaboration , : , S. Archambault , A. Archer , M. Beilicke , W. Benbow , K. Berger , R. Bird , J. Biteau , J. H. Buckley , V. Bugaev , M. Cerruti , X. Chen , L. Ciupik , E. Collins-Hughes , W. Cui , J. D. Eisch , A. Falcone , Q. Feng , J. P. Finley , P. Fortin , L. Fortson , A. Furniss , N. Galante , G. H. Gillanders , S. Griffin , G. Gyuk , N. Håkansson , J. Holder , C. A. Johnson , P. Kaaret , P. Kar , M. Kertzman , D. Kieda , M. J. Lang , S. McArthur , A. McCann , K. Meagher , J. Millis , P. Moriarty , R. A. Ong , A. N. Otte , J. S. Perkins , A. Pichel , M. Pohl , A. Popkow , H. Prokoph , E. Pueschel , K. Ragan , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , A. C. Rovero , G. H. Sembroski , K. Shahinyan , D. Staszak , I. Telezhinsky , J. V. Tucci , J. Tyler , A. Varlotta , S. P. Wakely , R. Welsing , A. Wilhelm , D. A. Williams , External Collaborators , : , S. Buson , J. Finke , M. Villata , C. Raiteri , H. D. Aller , M. F. Aller , A. Cesarini , W. P. Chen , M. A. Gurwell , S. G. Jorstad , G. N. Kimeridze , E. Koptelova , O. M. Kurtanidze , S. O. Kurtanidze , A. Lähteenmäki , V. M. Larionov , E. G. Larionova , H. C. Lin , B. McBreen , J. W. Moody , D. A. Morozova , A. P. Marscher , W. Max-Moerbeck , M. G. Nikolashvili , M. Perri , A. C. S. Readhead , J. L. Richards , J. A. Ros , A. C. Sadun , T. Sakamoto , L. A. Sigua , P. S. Smith , M. Tornikoski , I. S. Troitsky , A. E. Wehrle , B. Jordan

Not so Swift: 20 years of multiwavelength observations of Mrk 421 and Mrk 501

Aims. The blazars Mrk 421 and Mrk 501 have shown multiwavelength variability on all observed timescales, and have been well studied at high energies on short timescales. We aim to characterise the long-term temporal behaviour of these…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Gabrielle L. Taylor , Stefan J. Wagner , Alicja Wierzcholska , Michael Zacharias

X-ray Flares from Markarian 501

Motivated by the recent finding of hierarchical X-ray flaring phenomenon in Mrk 421, we conducted a systematic search for X-ray flares from Mrk 501, another well-known TeV blazar, by making use of the rich {\em RXTE} archival database. We…

Astrophysics · Physics 2009-11-10 Yongquan Xue , Wei Cui

The Exceptional Flare of Mrk 501 in 2014: Combined Observations with H.E.S.S. and FACT

The BL Lac type object Mrk 501 was observed at very high energies (E > 100 GeV) in 2014 with the upgraded H.E.S.S. (High Energy Stereoscopic System) phase 2 array. The data collected with the central 28m telescope allow for a broader energy…

High Energy Astrophysical Phenomena · Physics 2019-08-15 Gabriele Cologna , Nachiketa Chakraborty , Agnieszka Jacholkowska , Matthias Lorentz , Mahmoud Mohamed , Cedric Perennes , Carlo Romoli , Stefan J. Wagner , Alicja Wierzcholska , Daniela Dorner , Omar Kurtanidze

Variations of the physical parameters of the blazar Mrk 421 based on the analysis of the spectral energy distributions

We report on the variations of the physical parameters of the jet observed in the blazar Mrk 421, and discuss the origin of X-ray flares in the jet, based on the analysis of the several spectral energy distributions (SEDs). The SEDs are…

High Energy Astrophysical Phenomena · Physics 2020-05-27 Yurika Yamada , Makoto Uemura , Ryosuke Itoh , Yasushi Fukazawa , Masanori Ohno , Fumiya Imazato

News from a Multi-Wavelength Monitoring Campaign on Mrk 421

We conducted a daily monitoring campaign on Mrk 421 in 2003 and 2004 with the Whipple 10 m telescope and the large-area instruments aboard RXTE, simultaneously covering TeV and X-ray energies. Supporting observations at optical and radio…

Astrophysics · Physics 2019-08-14 Wei Cui

Hourly Spectral Variability of Mrk 421

Mrk 421 is the first TeV blazar found to exhibit significant spectral variability during strong flaring activity, showing hardening of the TeV spectrum in high emission states. Mrk 421 is also known to exhibit flux variability on time…

Astrophysics · Physics 2009-09-29 F. Krennrich , I. H. Bond , P. J. Boyle , S. M. Bradbury , J. H. Buckley