Related papers: VHE Observations of BL Lacertae Objects: 1995-2000

Evolutionary behaviour of BL Lac objects

We present analysis of a new flux limited sample of 72 X-ray selected BL Lacertae objects with known redshifts for 59 of them. We find the more X-ray dominated BL Lac having negative evolution with redshift, while intermediate objects show…

Astrophysics · Physics 2007-05-23 Volker Beckmann

Near-Infrared Observations of BL Lacertae Host Galaxies

Multi-band near-infrared images of twelve BL Lacertae objects were obtained with the 2.5m telescope at the Las Campanas Observatory in order to determine the properties of their underlying host galaxies. Resolved emission was clearly…

Astrophysics · Physics 2009-11-10 C. C. Cheung , C. Megan Urry , Riccardo Scarpa , Mauro Giavalisco

Time Averaged VHE Spectrum of Mrk 421 in 2005

The blazar Mrk421 was observed independently, but contemporaneously, in 2005 at TeV energies by MAGIC, the Whipple 10m telescope, and by a single VERITAS telescope during the construction phase of operations. A comparison of the time…

Astrophysics · Physics 2019-08-13 M. K. Daniel

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

Multi-color optical monitoring of the BL Lacertae object S5 0716+714 during the 2012 outburst

We have monitored the BL Lacertae object S5 0716+714 in the optical bands during 2012 January and February with long time spans on intraday timescales ($>$5 hr) and high time resolutions. During this monitoring period, the object shows…

High Energy Astrophysical Phenomena · Physics 2017-07-19 Shanwei Hong , Dingrong Xiong , Jinming Bai

Optical Monitoring of BL Lacertae Object OJ 287: a 40-Day Period?

We present the results of our optical monitoring of the BL Lacertae object OJ 287 during the first half of 2005. The source did not show large-amplitude variations during this period and was in a relatively quiescent state. A possible…

Astrophysics · Physics 2008-11-26 Jianghua Wu , Xu Zhou , Xuebing Wu , Fukun Liu , Bo Peng , Jun Ma , Zhenyu Wu , Zhaoji Jiang , Jiansheng Chen

Discovery of Very High Energy Gamma Rays from 1ES 1440+122

The 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,…

High Energy Astrophysical Phenomena · Physics 2016-08-10 VERITAS Collaboration , S. Archambault , A. Archer , A. Barnacka , B. Behera , M. Beilicke , W. Benbow , K. Berger , R. Bird , M. Boettcher , J. H. Buckley , V. Bugaev , J. V Cardenzana , M. Cerruti , X. Chen , J. L. Christiansen , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , H. J. Dickinson , J. Dumm , J. D. Eisch , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , H. Fleischhack , L. Fortson , A. Furniss , G. H. Gillanders , S. Godambe , S. Griffin , S. T. Griffiths , J. Grube , G. Gyuk , N. Haakansson , D. Hanna , J. Holder , G. Hughes , C. A. Johnson , P. Kaaret , P. Kar , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , S. Kumar , M. J. Lang , A. S Madhavan , G. Maier , S. McArthur , A. McCann , K. Meagher , J. Millis , P. Moriarty , T. Nelson , D. Nieto , A. O'Faolain de Bhroithe , R. A. Ong , A. N. Otte , N. Park , J. S. Perkins , M. Pohl , A. Popkow , H. Prokoph , E. Pueschel , J. Quinn , K. Ragan , J. Rajotte , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , G. H. Sembroski , K. Shahinyan , A. W. Smith , D. Staszak , K Sweeney , I. Telezhinsky , J. V. Tucci , J. Tyler , A. Varlotta , V. V. Vassiliev , S. P. Wakely , R. Welsing , A. Wilhelm , D. A. Williams , B. Zitzer

CANGAROO-III Observations of the 2006 Outburst of PKS2155-304

We have used the CANGAROO-III imaging atmospheric Cherenkov telescopes to observe the high-frequency-peaked BL Lacertae (HBL) object PKS 2155-304 between 2006 July 28 (MJD 53944) and August 2, triggered by the H.E.S.S. report that the…

Astrophysics · Physics 2012-08-27 III collaboration , Y. Sakamoto , K. Nishijima , T. Mizukami , E. Yamazaki , J. Kushida

VERITAS Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C 66A

The 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…

High Energy Astrophysical Phenomena · Physics 2010-12-14 VERITAS Collaboration , V. A. Acciari , E. Aliu , T. Arlen , M. Beilicke , W. Benbow , M. Bottcher , S. M. Bradbury , J. H. Buckley , V. Bugaev , Y. Butt , K. Byrum , A. Cannon , O. Celik , A. Cesarini , Y. C. Chow , L. Ciupik , P. Cogan , W. Cui , M. K. Daniel , R. Dickherber , T. Ergin , A. Falcone , S. J. Fegan , J. P. Finley , P. Fortin , L. Fortson , A. Furniss , D. Gall , K. Gibbs , G. H. Gillanders , S. Godambe , J. Grube , R. Guenette , G. Gyuk , D. Hanna , E. Hays , J. Holder , D. Horan , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , J. Kildea , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , G. Maier , A. McCann , M. McCutcheon , J. Millis , P. Moriarty , R. Mukherjee , T. Nagai , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , D. Petry , F. Pizlo , 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 , J. A. Toner , A. Varlotta , V. V. Vassiliev , R. G. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , D. A. Williams , S. Wissel , M. Wood , B. Zitzer

A sample of low-redshift BL Lacertae objects. II. EVN and MERLIN data and multi-wavelength analysis

We present new radio observations of 9 members of a sample of 29 nearby (z < 0.2) BL Lac objects. The new data have been obtained with the European VLBI Network and/or the MERLIN at 1.6 and 5 GHz and complement previous observations. For…

Astrophysics · Physics 2008-11-26 M. Giroletti , G. Giovannini , G. B. Taylor , R. Falomo

The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT

We present parallaxes, proper motions, and $J$-band photometry for 348 L and T dwarfs measured using the wide-field near-infrared camera WFCAM on the United Kingdom Infrared Telescope. This is the largest single batch of infrared parallaxes…

Solar and Stellar Astrophysics · Physics 2020-11-02 William M. J. Best , Michael C. Liu , Eugene A. Magnier , Trent J. Dupuy

Discovery of VHE gamma-rays from the BL Lac object PKS 0548-322

PKS 0548-322 (z=0.069) is a ``high-frequency-peaked'' BL Lac object and a candidate very high energy (VHE, E>100 GeV) gamma-ray emitter, due to its high X-ray and radio flux. Observations at the VHE band provide insights into the origin of…

High Energy Astrophysical Phenomena · Physics 2015-05-19 H. E. S. S. collaboration , : , F. Aharonian , A. G. Akhperjanian , G. Anton , U. Barres de Almeida , A. R. Bazer-Bachi , Y. Becherini , B. Behera , W. Benbow , K. Bernlöhr , A. Bochow , C. Boisson , J. Bolmont , V. Borrel , J. Brucker , F. Brun , P. Brun , R. Bühler , T. Bulik , I. Büsching , T. Boutelier , P. M. Chadwick , A. Charbonnier , R. C. G. Chaves , A. Cheesebrough , L. -M. Chounet , A. C. Clapson , G. Coignet , M. Dalton , M. K. Daniel , I. D. Davids , B. Degrange , C. Deil , H. J. Dickinson , A. Djannati-Ataï , W. Domainko , L. O'C. Drury , F. Dubois , G. Dubus , J. Dyks , M. Dyrda , K. Egberts , D. Emmanoulopoulos , P. Espigat , C. Farnier , F. Feinstein , A. Fiasson , A. Förster , G. Fontaine , M. Füssling , S. Gabici , Y. A. Gallant , L. Gérard , D. Gerbig , B. Giebels , J. F. Glicenstein , B. Glück , P. Goret , D. Göring , D. Hauser , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , A. Hoffmann , W. Hofmann , M. Holleran , S. Hoppe , D. Horns , A. Jacholkowska , O. C. de Jager , C. Jahn , I. Jung , K. Katarzyński , U. Katz , S. Kaufmann , E. Kendziorra , M. Kerschhagg , D. Khangulyan , B. Khélifi , D. Keogh , W. Kluźniak , T. Kneiske , Nu. Komin , K. Kosack , G. Lamanna , J. -P. Lenain , T. Lohse , V. Marandon , J. M. Martin , O. Martineau-Huynh , A. Marcowith , J. Masbou , D. Maurin , T. J. L. McComb , M. C. Medina , R. Moderski , E. Moulin , M. Naumann-Godo , M. de Naurois , D. Nedbal , D. Nekrassov , B. Nicholas , J. Niemiec , S. J. Nolan , S. Ohm , J-F. Olive , E. de Oña Wilhelm , K. J. Orford , M. Ostrowski , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier , P. -O. Petrucci , S. Pita , G. Pühlhofer , M. Punch , A. Quirrenbach , B. C. Raubenheimer , M. Raue , S. M. Rayner , M. Renaud , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees , G. Rowell , B. Rudak , C. B. Rulten , J. Ruppel , V. Sahakian , A. Santangelo , R. Schlickeiser , F. M. Schöck , R. Schröder , U. Schwanke , S. Schwarzburg , S. Schwemmer , A. Shalchi , M. Sikora , J. L. Skilton , H. Sol , D. Spangler , L. Stawarz , R. Steenkamp , C. Stegmann , F. Stinzing , G. Superina , A. Szostek , P. H. Tam , J. -P. Tavernet , R. Terrier , O. Tibolla , M. Tluczykont , C. van Eldik , G. Vasileiadis , C. Venter , L. Venter , J. P. Vialle , P. Vincent , M. Vivier , H. J. Völk , F. Volp , S. J. Wagner , M. Ward , A. A. Zdziarski , A. Zech

VHE Gamma Rays from PKS 2155-304

The X-ray selected BL Lac PKS 2155-304 has been observed using the University of Durham Mark 6 very high energy gamma ray telescope during 1998. We find no evidence for TeV emission during these recent observations when the X-ray flux was…

Astrophysics · Physics 2007-05-23 P. M. Chadwick , K. Lyons , T. J. L. McComb , K. J. Orford , J. L. Osborne , S. M. Rayner , S. E. Shaw , K. E. Turver

EBL effect on the observation of multi-TeV flaring of 2009 from Markarian 501

Markarian 501 is a high-peaked BL Lacertae object and has undergone many major outburst since its discovery in 1996. As a part of the multiwavelength campaign, in the year 2009 this blazar was observed for 4.5 months from March 9 to August…

High Energy Astrophysical Phenomena · Physics 2017-02-01 Sarira Sahu , Marco Vladimir Lemus Yáñez , Luis Salvador Miranda , Alberto Rosales de León , Virendra Gupta

Longterm Optical Monitoring of Bright BL Lacertae Objects with ATOM: Spectral Variability and Multiwavelength Correlations

Blazars are the established sources of an intense and variable non-thermal radiation extending from radio wavelengths up to HE and VHE gamma-rays. Understanding the spectral evolution of blazars in selected frequency ranges, as well as…

High Energy Astrophysical Phenomena · Physics 2014-12-24 Alicja Wierzcholska , Michał Ostrowski , Łukasz Stawarz , Stefan Wagner , Marcus Hauser

ROSAT Observations of BL Lacertae Objects

We present soft X-ray spectra of 74 BL Lacertae objects observed with the PSPC detector on board of the ROSAT satellite. The sample contains all BL Lac objects detected during the pointed observation phase as a target or serendipitously. We…

Astrophysics · Physics 2007-05-23 G. Lamer , H. Brunner , R. Staubert

APEX sub-mm monitoring of gamma-ray blazars

So far, no systematic long-term blazar monitoring programs and detailed variability studies exist at sub-mm wavelengths. Here, we present a new sub-mm blazar monitoring program using the APEX 12-m telescope. A sample of about 40 gamma-ray…

High Energy Astrophysical Phenomena · Physics 2012-06-19 S. Larsson , L. Fuhrmann , A. Weiss , E. Angelakis , T. P. Krichbaum , I. Nestoras , J. A. Zensus , M. Axelsson , D. Nilsson , F. Ryde , L. Hjalmarsdotter , J. Larsson , A. Lundgren , F. Mac-Auliffe , R. Parra , G. Siringo

Host galaxy subtraction of TeV candidate BL Lacertae objects

We have derived R-band host galaxy fluxes of 20 TeV candidate BL Lacertae objects as a function of aperture radius and FWHM. The results are given as correction tables, that list the fluxes (in mJy) of all ``contaminating'' sources (host…

Astrophysics · Physics 2009-11-13 K. Nilsson , M. Pasanen , L. O. Takalo , E. Lindfors , A. Berdyugin , S. Ciprini , J. Pforr

ESO VLT optical spectroscopy of BL Lacertae objects. III. An extension of the sample

We present results of an ongoing program at the ESO VLT for spectroscopy of BL Lac objects lacking a firm redshift estimate and here we report on 15 objects. For 11 sources we confirm the BL Lac classification, and we determine new…

Astrophysics · Physics 2008-10-21 B. Sbarufatti , S. Ciprini , J. Kotilainen , R. Decarli , A. Treves , A. Veronesi , R. Falomo

The HST Survey of BL Lacertae Objects: Morphological Properties of Low redshift Host Galaxies

We report on the optical properties of a sample of 30 BL Lac host galaxies in the redshift range $0.03<z<0.2$, as derived from HST observations. All galaxies are fully resolved in the WFPC2 (F702W filter) images, allowing a quantitative…

Astrophysics · Physics 2009-10-31 R. Falomo , R. Scarpa , A. Treves , C. M. Urry