Статья

THE WHOLE EARTH BLAZAR TELESCOPE CAMPAIGN ON THE INTERMEDIATE BL LAC OBJECT 3C 66A IN 2007-2008

M. BöttcherAstrophysical Institute, Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701, USAK. FultzAstrophysical Institute, Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701, USAH. D. AllerDepartment of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109-1042, USAM. F. AllerDepartment of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109-1042, USAJ. ApodacaDepartment of Physics, University of Colorado Denver, Campus Box 157, P.O. Box 173364, Denver, CO 80217-3364, USAA. A. ArkharovPulkovo Observatory, Pulkovskoye Shosse, 65, 196140, St. Petersburg, RussiaU. BachMax-Planck-Institut für Radioastronomie, Radioobservatorium Effelsberg, Max-Planck-Straße 28, D-53902 Bad Münstereifel-Effelsberg, GermanyR. BachevInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd., 1784 Sofia, BulgariaA. BerdyuginTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandC. S. BuemiOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyP. CalcideseOsservatorio Astronomico della Regione Autonoma Valle d'Aosta, ItalyD. CarosatiOsservatorio di Armenzano, Assisi, ItalyP. CharlotCNRS, Laboratoire d'Astrophysique de Bordeaux-UMR 5804, Floirac, FranceS. CipriniOsservatorio Astronomico, Università di Perugia, Via B. Bonfigli, I-06126 Perugia, ItalyA. Di PaolaIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Roma, Via Frascati, Monteporzio Cantone, Roma, ItalyM. DolciIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Teramo, Via Maggini, Teramo, ItalyН. В. ЕфимоваPulkovo Observatory, Pulkovskoye Shosse, 65, 196140, St. Petersburg, RussiaE. Forné ScurratsCode MPC B29, Astronomical Observatory L'Ampolla, Tarragona, SpainA. FrascaOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyAlok C. GuptaAryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital-263 129, IndiaV. A. Hagen‐ThornAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaJ. HeidtD. HiriartInstituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, 22800 Ensenada, B.C., MexicoT. S. KonstantinovaAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaE. N. KopatskayaAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaA. LähteenmäkiMetsähovi Radio Observatory, Helsinki University of Technology TKK, Metsähovintie 114, 02540 Kylmälä, FinlandL. LanteriIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyV. M. LarionovAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaJ.-F. Le CampionCNRS, Laboratoire d'Astrophysique de Bordeaux-UMR 5804, Floirac, FranceP. LetoINAF, Instituto di Radioastronomia, Sezione di Noto, ItalyE. LindforsTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandE. Marilli B. MihovInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd., 1784 Sofia, BulgariaE. NieppolaMetsähovi Radio Observatory, Helsinki University of Technology TKK, Metsähovintie 114, 02540 Kylmälä, FinlandK. NilssonTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandJ. M. Ohlert E. OvcharovSofia University “St. Kliment Ohridski,” Faculty of Physics, 5 James Bourchier Blvd., 1164 Sofia, BulgariaPertti PääkkönenM. PasanenTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandB. RagozzineAstrophysical Institute, Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701, USAC. M. RaiteriIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyJavier RosAgrupaciòn Astronomica de Sabadell, Sabadell 08200, SpainA. C. SadunDepartment of Physics, University of Colorado Denver, Campus Box 157, P.O. Box 173364, Denver, CO 80217-3364, USAA. SánchezGualba Observatory, MPC 442, Barcelona, SpainE. SemkovInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd., 1784 Sofia, BulgariaM. SorciaInstituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, 04510 México, D.F., MexicoA. StrigachevInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd., 1784 Sofia, BulgariaL. O. TakaloTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandM. TornikoskiMetsähovi Radio Observatory, Helsinki University of Technology TKK, Metsähovintie 114, 02540 Kylmälä, FinlandC. TrigilioOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyG. UmanaOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyA. ValchevaInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd., 1784 Sofia, BulgariaM. VillataIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyA. E. VolvachCrimean Astrophysical Observatory, Naunchy, Crimea 98409, UkraineJianghua WuNational Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012, ChinaXin ZhouNational Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012, China

2009en

ABI

Аннотация

Prompted by a high optical state in 2007 September, the Whole Earth Blazar Telescope consortium organized an intensive optical, near-IR (JHK) and radio observing campaign on the intermediate BL Lac object 3C 66A throughout the fall and winter of 2007-2008. In this paper, we present data from 28 observatories in 12 countries, covering the observing season from late 2007 July through 2008 February. The source remained in a high optical state throughout the observing period and exhibited several bright flares on timescales of ~10 days. This included an exceptional outburst around 2007 September 15-20, reaching a peak brightness at R~ 13.4. Our campaign revealed microvariability with flux changes up to |dR/dt|~ 0.02 mag hr–1. Our observations do not reveal evidence for systematic spectral variability in the overall high state covered by our campaign, in agreement with previous results. In particular, we do not find evidence for spectral hysteresis in 3C 66A for which hints were found in an earlier campaign in a somewhat lower flux state. We also did not find any evidence for spectral lags in the discrete correlation functions between different optical bands. We infer a value of the magnetic field in the emission region of B~ 19 e 2/7 B τ–6/7 h D 13/7 1 G, where eB is the magnetic field equipartition fraction, τ h is the shortest observed variability timescale in units of hours, and D 1 is the Doppler factor in units of 10. From the lack of systematic spectral variability, we can derive an upper limit on the Doppler factor, D <= 28 τ–1/8 h e 3/16 B . This is in perfect agreement with superluminal motion measurements with the VLBI/VLBA of βapp <= 27 and argues against models with very high Lorentz factors of Γ gsim 50, required for a one-zone synchrotron-self-Compton interpretation of some high-frequency-peaked BL Lac objects detected at TeV γ-ray energies. The radio-to-optical data presented in this paper are stored in the WEBT archive; for questions regarding their availability, contact the WEBT President Massimo Villata ().

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Идентификаторы

DOI: 10.1088/0004-637x/694/1/174

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