Multiwavelength Observations of 3C 66A during the WEBT campaign of 2003 - 2004

Abstract

The BL Lac object 3C 66A was the target of an extensive multiwavelength monitoring campaign from July 2003 through April 2004, involving observations throughout the electromagnetic spectrum. Radio, infrared, and optical observations were carried out by the WEBT-ENIGMA collaboration. At higher energies, 3C 66A was observed in X-rays (RXTE), and at very-high-energy (VHE) gamma-rays (STACEE, VERITAS). In addition, the source has been observed with the VLBA at 9 epochs throughout the period September 2003 - December 2004, including 3 epochs contemporaneous with the core campaign.The WEBT campaign revealed microvariability with flux changes of ~ 5 % on time scales as short as \~ 2 hr. The source was in a relatively bright state, with several bright flares on time scales of several days. The SED indicates a $\nu F_{\nu }$ peak in the optical regime. A weak trend of optical spectral hysteresis with a trend of spectral softening throughout both the rising and decaying phases, has been found. The 3 - 10 keV X-ray flux of 3C 66A during the core campaign was historically high and its spectrum very soft, indicating that the low-frequency component of the broadband SED extends beyond ~ 10 keV. No significant X-ray flux and/or spectral variability was detected. STACEE and Whipple observations provided upper flux limits at > 150 GeV and > 390 GeV, respectively. The 22 and 43 GHz data from the 3 VLBA epochs between September 2003 and January 2004 indicate a smooth jet with only moderate internal structure. Evidence for superluminal motion (8.5 +/- 5.6 h^{-1} c) was found in only one out of 6 components. The radial radio brightness profile suggests a magnetic field decay $\propto r^{-1}$ and, thus, a predominantly perpendicular magnetic field.

27 pages, including 17 figures. Accepted for publication in ApJ

References in corpus (29)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• A Unifying View of the Spectral Energy Distributions of Blazars
• A theoretical unifying scheme for gamma-ray bright blazars
• BL Lac Objects in the Synchrotron Proton Blazar Model
• A Proton Synchrotron Blazar Model for Flaring in Markarian~501
• Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Superluminal Motion of Gamma-Ray Bright Blazars
• VERITAS: the Very Energetic Radiation Imaging Telescope Array System
• TeV candidate BL Lac objects
• Optical and radio variability of the BL Lac object AO 0235+16: a possible 5-6 year periodicity
• The WEBT BL Lac Campaign 2000
• Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514
• Helical Magnetic Fields Associated with the Relativistic Jets of Four BL Lac Objects
• On the geometrical origin of periodicity in blazar-type sources
• VHE Gamma Rays from PKS 2155-304
• The WEBT BL Lacertae Campaign 2001 and its extension
• Parsec-Scale Blazar Monitoring: Proper Motions
• Survey of Instantaneous 1-22 GHz Spectra of 550 Compact Extragalactic Objects with Declinations from -30deg to +43deg
• The Twin--Jet System in NGC 1052: VLBI-Scrutiny of the Obscuring Torus
• Detection of TeV Gamma Rays from the BL Lac Object 1ES1959+650 with the Whipple 10m Telescope
• Detection of the BL Lac Object H1426+428 at TeV Gamma Ray Energies
• Extragalactic Gamma-ray Absorption and the Intrinsic Spectrum of Mkn 501 During the 1997 Flare
• Spectral Slope Variability of BL Lac Objects in the Optical Band
• Coordinated Multiwavelength Observations of BL Lacertae in 2000
• Infrared Variation of Radio Selected BL Lacertae Objects
• XMM-Newton observations of the hot-gas atmospheres of 3C 66B and 3C 449
• Constraints on the Very High Energy Emission from BL Lacertae Objects
• Observations of the BL Lac Object 3C 66A with STACEE
• The WEBT campaign to observe AO 0235+16 in the 2003-2004 observing season
• A Search for TeV Gamma-Ray Emission from High-Peaked Flat Spectrum Radio Quasars Using the Whipple Air-Cherenkov Telescope

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• Ten-year optical monitoring of PKS 0735+178: historical comparison, multiband behaviour and variability timescales
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• Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38
• XMM-Newton observations of a sample of gamma-ray loud active galactic nuclei
• Multiwavelength behaviour of the blazar 3C279: decade-long study from $\gamma$-ray to radio
• The WEBT Campaign on the Intermediate BL Lac Object 3C66A in 2007-2008
• A Consolidated Framework of the Color Variability in Blazars: Long-Term Optical/Near-Infrared Observations of 3C 279
• Optical Intraday Variability Studies of Ten Low Energy Peaked Blazars
• Multi-frequency monitoring of gamma-ray loud blazars: I. Light curves and spectral energy distributions
• Short Term Flux and Colour Variations in Low-Energy Peaked Blazars
• Swift observations of IBL and LBL objects
• Redshift Limits of BL Lacertae Objects from Optical Spectroscopy
• Multi-color optical monitoring of ten blazars from 2005 to 2011
• Optical Variability of TeV Blazars on long time-scales
• Spectral Energy Distribution variation in BL Lacs and FSRQs
• Modeling the Spectral Energy Distribution and Variability of 3C 66A during the WEBT campaign of 2003 -- 2004
• Multi-wavelength study of flaring activity in HBL 1ES 1959+650 during 2015-16
• Optical intra-day variability in 3C 66A: 10 years of observations
• Multi-epoch VLBA observations of 3C 66A
• MOJAVE -- XXII. Brightness temperature distributions and geometric profiles along parsec-scale AGN jets
• Mechanism of very high energy radiation in BL Lacertae object 3C 66A
• Variability and spectral variation of 3C 66A
• Long-Term X-Ray monitoring of NGC6251: Evidence for a jet-dominated radio galaxy
• Multi-epoch, multi-frequency VLBI study of the parsec-scale jet in the blazar 3C 66A
• VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz
• GLAST Large Area Telescope Multiwavelength Planning