Photometric Calibration of Stars in the Fields of Selected BL Lacertae Objects and Quasars

Smith, Paul S.; Balonek, T. J.

doi:10.1086/316244

Cited by 23 publications

(23 citation statements)

References 26 publications

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“…Instrumental magnitudes are then converted to standard Johnson-Cousins magnitudes using the sequences of stars reported in Fiorucci (1995), , and Fiorucci et al (1998). A comparison with other published sequences shows a general agreement within typical standard deviations (Smith & Balonek 1998;Webb & Malkan 2000;Gonzalez-Perez et al 2001).…”

Section: Observationsmentioning

confidence: 81%

The continuum spectral features of blazars in the optical region

Fiorucci

Ciprini

Tosti

2004

A&A

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Abstract. Many quasi-simultaneous optical observations of 37 blazars were obtained at the Perugia University Observatory over the last ten years. In this paper we analyze the dereddened spectral flux distribution in the optical frequency range, and we compare our results with the overall spectral energy distribution (SED). The implications for existing models of the objects are briefly discussed. In particular, we show how the LBLs have a spectral slope α 1.5, as expected from Synchrotron SelfCompton models, while the optical emission of HBLs and FSRQs is probably contaminated by other components. Moreover, we show evidence of how the spectral index vs. flux plot exhibits a characteristic loop-like pattern that is probably due to changes in the injection of accelerated particles.

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Section: Observationsmentioning

confidence: 81%

The continuum spectral features of blazars in the optical region

Fiorucci

Ciprini

Tosti

2004

A&A

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“…aperture and a sky annulus of inner diameter 24 ′′ and outer diameter 44 ′′ . Star 8 of Smith & Balonek (1998), with a known magnitude of R = 13.10 ± 0.03, was used as the primary comparison star. A faint star ∼ 10 ′′ west of star 8 contributes < 1% to the brightness of star 8, and is ignored.…”

Section: Multi-frequency Light Curvesmentioning

confidence: 99%

The 2016 June Optical and Gamma-Ray Outburst and Optical Microvariability of the Blazar 3C 454.3

Weaver

Balonek

Jorstad

et al. 2019

ApJ

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The quasar 3C454.3 underwent a uniquely-structured multi-frequency outburst in June 2016. The blazar was observed in the optical R band by several ground-based telescopes in photometric and polarimetric modes, at γ-ray frequencies by the Fermi Large Area Telescope, and at 43 GHz with the Very Long Baseline Array. The maximum flux density was observed on 2016 June 24 at both optical and γ-ray frequencies, reaching S max opt = 18.91 ± 0.08 mJy and S max γ = 22.20 ± 0.18 × 10 −6 ph cm −2 s −1 , respectively. The June 2016 outburst possessed a precipitous decay at both γ-ray and optical frequencies, with the source decreasing in flux density by a factor of 4 over a 24-hour period in R band. Intraday variability was observed throughout the outburst, with flux density changes between 1 and 5 mJy over the course of a night. The precipitous decay featured statistically significant quasi-periodic micro-variability oscillations with an amplitude of ∼ 2-3% about the mean trend and a characteristic period of 36 minutes. The optical degree of polarization jumped from ∼ 3% to nearly 20% during the outburst, while the position angle varied by ∼ 120 • . A knot was ejected from the 43 GHz core on 2016 Feb 25, moving at an apparent speed v app = 20.3c ± 0.8c. From the observed minimum timescale of variability τ min opt ≈ 2 hr and derived Doppler factor δ = 22.6, we find a size of the emission region r 2.6 × 10 15 cm. If the quasi-periodic micro-variability oscillations are caused by periodic variations of the Doppler factor of emission from a turbulent vortex, we derive a rotational speed of the vortex ∼ 0.2c.

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“…We used comparison stars in the fields of the AGNs (Smith et al 1985;Smith & Balonek 1998) to calibrate nearly all of the photometry. We determined the V magnitudes of 3C 111 and 3C 120 on 1999 February 13 from the photometric solution provided by observations of equatorial standard stars (Landolt 1983).…”

Section: Optical Polarization Observationsmentioning

confidence: 99%

Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior

et al. 2007

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We report on multifrequency linear polarization monitoring of 15 active galactic nuclei containing highly relativistic jets with apparent speeds from $4c to >40c. The measurements were obtained at optical, 1 mm, and 3 mm wavelengths, and at 7 mm with the Very Long Baseline Array. The data show a wide range in degree of linear polarization among the sources, from <1% to >30%, and interday polarization variability in individual sources. The polarization properties suggest separation of the sample into three groups with low, intermediate, and high variability of polarization in the core at 7 mm (LVP, IVP, and HVP, respectively). The groups are partially associated with the common classification of active galactic nuclei as radio galaxies and quasars with low optical polarization (LVP), BL Lacertae objects (IVP), and highly optically polarized quasars (HVP). Our study investigates correlations between total flux, fractional polarization, and polarization position angle at the different wavelengths. We interpret the polarization properties of the sources in the sample through models in which weak shocks compress turbulent plasma in the jet. The differences in the orientation of sources with respect to the observer, jet kinematics, and abundance of thermal matter external to the jet near the core can account for the diversity in the polarization properties. The results provide strong evidence that the optical polarized emission originates in shocks, most likely situated between the 3 and 7 mm VLBI cores. They also support the idea that the 1 mm core lies at the edge of the transition zone between electromagnetically dominated and turbulent hydrodynamic sections of the jet.

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Photometric Calibration of Stars in the Fields of Selected BL Lacertae Objects and Quasars

Cited by 23 publications

References 26 publications

The continuum spectral features of blazars in the optical region

The continuum spectral features of blazars in the optical region

The 2016 June Optical and Gamma-Ray Outburst and Optical Microvariability of the Blazar 3C 454.3

Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior

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