Related papers: H.E.S.S. Observations of PKS 2155-304

VERITAS observations of exceptionally bright TeV flares from LS I +61$^\circ$ 303

The very-high-energy (VHE; E > 100 GeV) gamma-ray experiment, VERITAS, detected exceptionally bright flares from the high-mass X-ray binary LS I +61$^\circ$ 303 during the period October-December 2014. LS I +61$^\circ$ 303 is a known VHE…

High Energy Astrophysical Phenomena · Physics 2015-08-28 Anna O'Faolain de Bhroithe , VERITAS collaboration

The blazar PKS 0528+134: new results from BeppoSAX observations

BeppoSAX observed 8 times the gamma-ray bright blazar PKS 0528+134 in Feb. and Mar. 1997, during a multiwavelength campaign involving EGRET, onboard CGRO, and ground based telescopes. The source was in its faintest X-ray state observed so…

Astrophysics · Physics 2007-05-23 G. Ghisellini , L. Costamante , G. Tagliaferri , L. Maraschi , A. Celotti , G. Fossati , E. Pian , A. Comastri , G. De Francesco , L. Lanteri , C. M. Raiteri , G. Sobrito M. Villata , I. S. Glass , P. Grandi , P. Padovani , C. Perola , A. Treves

Testing the emission models of blazar jets with the MAGIC telescopes

The MAGIC telescopes discovered very high energy (VHE, E>100 GeV) gamma-ray emission coming from the distant Flat Spectrum Radio Quasar (FSRQ) PKS 1222+21 (4C +21.35, z=0.432). It is the second most distant VHE gamma-ray source, with well…

High Energy Astrophysical Phenomena · Physics 2019-08-13 J. Becerra-González , A. Stamerra , K. Saito , D. Mazin , F. Tavecchio , L. Maraschi , E. Prandini , J. Sitarek , K. Berger

Very high energy $\gamma$-ray emission from two blazars of unknown redshift and upper limits on their distance

We report on the detection of very-high-energy (VHE; $E > 100$ GeV) $\gamma$-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or…

High Energy Astrophysical Phenomena · Physics 2020-04-29 H. E. S. S. Collaboration , H. Abdalla , R. Adam , F. Aharonian , F. Ait Benkhali , E. O. Angüner , M. Arakawa , C. Arcaro , C. Armand , T. Armstrong , H. Ashkar , M. Backes , V. Baghmanyan , V. Barbosa Martins , A. Barnacka , M. Barnard , Y. Becherini , D. Berge , K. Bernlöhr , M. Böttcher , C. Boisson , J. Bolmont , S. Bonnefoy , J. Bregeon , M. Breuhaus , F. Brun , P. Brun , M. Bryan , M. Büchele , T. Bulik , T. Bylund , S. Caroff , A. Carosi , S. Casanova , T. Chand , S. Chandra , A. Chen , G. Cotter , M. Curyło , I. D. Davids , J. Davies , C. Deil , J. Devin , P. deWilt , L. Dirson , A. Djannati-Ataï , A. Dmytriiev , A. Donath , V. Doroshenko , J. Dyks , K. Egberts , F. Eichhorn , G. Emery , J. -P. Ernenwein , K. Feijen , S. Fegan , A. Fiasson , G. Fontaine , S. Funk , M. Füßling , S. Gabici , Y. A. Gallant , G. Giavitto , L. Giunti , D. Glawion , J. F. Glicenstein , D. Gottschall , M. -H. Grondin , J. Hahn , M. Haupt , G. Hermann , J. A. Hinton , W. Hofmann , C. Hoischen , T. L. Holch , M. Holler , M. H{\"}orbe , D. Horns , D. Huber , H. Iwasaki , M. Jamrozy , D. Jankowsky , F. Jankowsky , A. Jardin-Blicq , V. Joshi , I. Jung-Richardt , M. A. Kastendieck , K. Katarzynski , M. Katsuragawa , U. Katz , D. Khangulyan , B. Khélifi , S. Klepser , W. Kluzniak , Nu. Komin , R. Konno , K. Kosack , D. Kostunin , M. Kreter , G. Lamanna , A. Lemière , M. Lemoine-Goumard , J. -P. Lenain , E. Leser , C. Levy , T. Lohse , I. Lypova , J. Mackey , J. Majumdar , D. Malyshev , D. Malyshev , V. Marandon , P. Marchegiani , A. Marcowith , A. Mares , G. Martí-Devesa , R. Marx , G. Maurin , P. J. Meintjes , R. Moderski , M. Mohamed , L. Mohrmann , C. Moore , P. Morris , E. Moulin , J. Muller , T. Murach , S. Nakashima , K. Nakashima , M. de Naurois , H. Ndiyavala , F. Niederwanger , J. Niemiec , L. Oakes , P. O'Brien , H. Odaka , S. Ohm , E. de Ona Wilhelmi , M. Ostrowski , M. Panter , R. D. Parsons , 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 , Q. Remy , M. Renaud , F. Rieger , L. Rinchiuso , C. Romoli , G. Rowell , B. Rudak , E. Ruiz-Velasco , V. Sahakian , S. Sailer , S. Saito , D. A. Sanchez , A. Santangelo , M. Sasaki , M. Scalici , F. Schüssler , H. M. Schutte , U. Schwanke , S. Schwemmer , M. Seglar-Arroyo , M. Senniappan , A. S. Seyffert , N. Shafi , K. Shiningayamwe , R. Simoni , A. Sinha , H. Sol , A. Specovius , S. Spencer , M. Spir-Jacob , Ł. Stawarz , R. Steenkamp , C. Stegmann , C. Steppa , T. Takahashi , T. Tavernier , A. M. Taylor , R. Terrier , D. Tiziani , M. Tluczykont , L. Tomankova , 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 , P. Vincent , J. Vink , H. J. Völk , T. Vuillaume , Z. Wadiasingh , S. J. Wagner , J. Watson , F. Werner , R. White , A. Wierzcholska , R. Yang , H. Yoneda , M. Zacharias , R. Zanin , D. Zargaryan , A. A. Zdziarski , A. Zech , S. J. Zhu , J. Zorn , N. Żywucka , M. Cerruti

BeppoSAX Observations of PKS 2155-304 during an active Gamma-ray State

PKS 2155-304 was observed with BeppoSAX in November 1997 for 64 ksec (total elapsed time 33.5 hours) and, for the first time, simultaneously in gamma-rays with EGRET on board the Compton Gamma Ray Observatory and with the ground based TeV…

Astrophysics · Physics 2007-05-23 L. Maraschi , L. Chiappetti , F. Tavecchio , A. Celotti , G. Fossati , G. Ghisellini , P. Giommi , E. Pian , G. Tagliaferri , A. Treves , Y. H. Zhang

REM near-IR and optical multiband observations of PKS2155-304 in 2005

Spectral variability is the main tool for constraining emission models of BL Lac objects. By means of systematic observations of the BL Lac prototype PKS 2155-304 in the infrared-optical band, we explore variability on the scales of months,…

Astrophysics · Physics 2009-11-16 A. Dolcini , F. Farfanelli , S. Ciprini , A. Treves , S. Covino , G. Tosti , E. Pian , B. Sbarufatti , E. Molinari , G. Chincarini , F. M. Zerbi , G. Malaspina , P. Conconi , L. Nicastro , E. Palazzi , V. Testa , F. Vitali , L. A. Antonelli , J. Danziger , G. Tagliaferri , E. Meurs , S. Vergani , A. Fernandez-Soto , E. Distefano , G. Cutispoto , F. D'Alessio

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

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

The Crab Nebula and Pulsar between 500 GeV and 80 TeV: Observations with the HEGRA stereoscopic air Cherenkov telescopes

The Crab supernova remnant has been observed regularly with the stereoscopic system of 5 imaging air Cherenkov telescopes that was part of the High Energy Gamma Ray Astronomy (HEGRA) experiment. In total, close to 400 hours of useful data…

Astrophysics · Physics 2010-01-28 F. Aharonian et al.

Long-term multiwavelength observations of 1ES 1218+304: physical implications of the flux and spectral variability

This paper presents the results of a detailed timing and spectral analysis of the TeV-detected blazar 1ES 1218+304, focused on the observations performed with the different instruments onboard the Neil Gehrels Swift Observatory in the…

Astrophysics of Galaxies · Physics 2025-04-22 B. Kapanadze , A. Gurchumelia , M. Aller

The Temporal Characteristics of the TeV Gamma-Radiation from Mkn 501 in 1997, I: Data from the Stereoscopic Imaging Atmospheric Cherenkov Telescope System of HEGRA

During 1997, the BL Lac Object Mkn 501 was the brightest known object in the TeV gamma-ray sky. The emission was characterized by dramatic variations in intensity with a mean flux exceeding by a factor of three the steady gamma-ray flux of…

Astrophysics · Physics 2007-05-23 F. Aharonian

20 years of monitoring: PKS 2155-304 and PKS 1510-089 in the eyes of Swift and Fermi. I. The case of PKS 2155-304

We present a comprehensive 20-year multiwavelength variability study of the blazar PKS 2155-304, one of the most luminous and extensively monitored high-frequency-peaked BL Lac objects in the southern hemisphere. Using Fermi-LAT…

High Energy Astrophysical Phenomena · Physics 2026-04-02 A. Wierzcholska , M. Zacharias

Redshift constrain of BL Lac PKS 1424+240

In the period between 2009 and 2015, several very high-energy (VHE $> 100$ GeV) gamma-ray flaring events from the BL Lac object PKS 1424+240 were observed by the Cerenkov telescopes VERITAS and MAGIC. It had uncertain redshift ($z$) and…

High Energy Astrophysical Phenomena · Physics 2024-08-05 Sarira Sahu , D. I. Páez-Sánchez , B. Medina-Carrillo , R. de J. Pacheco-Aké , G. Sánchez-Colón , Subhash Rajpoot

Very High Energy Gamma-ray spectral properties of Mrk 501 from CAT Cerenkov telescope observations in 1997

The BL Lac object Mrk 501 went into a very high state of activity during 1997, both in VHE gamma-rays and X-rays. We present here results from observations at energies above 250 GeV carried out between March and October 1997 with the CAT…

Astrophysics · Physics 2007-05-23 A. Djannati-Atai , F. Piron , A. Barrau , L. Iacoucci , M. Punch , J. -P. Tavernet , R. Bazer-Bachi , H. Cabot , L. -M. Chounet , G. Debiais , B. Degrange , J. -P. Dezalay , D. Dumora , P. Espigat , B. Fabre , P. Fleury , G. Fontaine , C. Ghesquière , P. Goret , C. Gouiffes , I. A. Grenier , S. Le Bohec , I. Malet , C. Meynadier , G. Mohanty , E. Nuss , E. Paré , J. Québert , K. Ragan , C. Renault , M. Rivoal , L. Rob , K. Schahmaneche , D. A. Smith

Observation of Very High Energy Gamma Rays from HESS J1804-216 with CANGAROO-III Telescopes

We observed the unidentified TeV gamma-ray source HESS J1804-216 with the CANGAROO-III atmospheric Cerenkov telescopes from May to July in 2006. We detected very high energy gamma rays above 600 GeV at the 10 sigma level in an effective…

Astrophysics · Physics 2019-08-14 Y. Higashi , H. Kubo , T. Yoshida , R. Enomoto , T. Tanimori , P. G. Edwards , T. Naito

Discovery of the mysterious gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2

Thanks to the use of advanced analysis techniques, the H.E.S.S. imaging Cherenkov telescope array has now reached a sensitivity level allowing the detection of sources with fluxes around 1% of the Crab with a limited observation time (less…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Hélène Laffon , Fabio Acero , Francois Brun , Bruno Khélifi , Gerd Pühlhofer , Régis Terrier

Gamma ray flares from Mrk421 in 2008 observed with the ARGO-YBJ detector

In 2008 the blazar Markarian 421 entered a very active phase and was one of the brightest sources in the sky at TeV energies, showing frequent flaring episodes. Using the data of ARGO-YBJ, a full coverage air shower detector located at…

High Energy Astrophysical Phenomena · Physics 2015-05-18 G. Aielli et al.

Serendipitous discovery of the unidentified extended TeV gamma-ray source HESS J1303-631

The serendipitous discovery of an unidentified extended TeVgamma-ray source close to the galactic plane named HESS J1303-631 at a significance of 21 standard deviations is reported. The observations were performed between February and June…

Astrophysics · Physics 2012-08-27 H. E. S. S. Collaboration , : , F. Aharonian

Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects

All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…

Astrophysics · Physics 2019-08-12 M. Meyer

X-ray Intraday Variability of the TeV Blazar PKS 2155-304 with Suzaku During 2005-2014

We have examined 13 pointed observations of the TeV emitting high synchrotron peak blazar PKS 2155-304, taken by the Suzaku satellite throughout its operational period. We found that the blazar showed large-amplitude intraday variabilities…

High Energy Astrophysical Phenomena · Physics 2021-03-17 Zhongli Zhang , Alok C. Gupta , Haritma Gaur , Paul J. Wiita , Tao An , Yang Lu , Shida Fan , Haiguang Xu