Related papers: Polarization microvariability of BL Lac objects

We use a continuous wavelet transform to analyze more than two decades of data for the BL~Lac object OJ~287 acquired as part of the UMRAO variability program. We find clear evidence for a persistent modulation of the total flux and…

Here we present highlights from VERITAS observations of high-frequency-peaked BL Lac objects (HBLs). We discuss the key science motivations for observing these sources -- including performing multiwavelength campaigns critical to…

We present measurements of rotations of the optical polarization of blazars during the second year of operation of RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection…

In this paper, we explore the behavior of optical polarization during the multi-wavelength outburst of the blazar Mrk 421 detected in February 2010. We use optical polarization measurements in the wavelength range 500-700 nm from SPOL…

We report results from a 1 week multi-wavelength campaign to monitor the BL Lac object S5 0716+714 (on December 9-16, 2009). In the radio bands the source shows rapid (~ (0.5-1.5) day) intra-day variability with peak amplitudes of up to ~…

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…

The BL Lac object S5 0716+714 was monitored during a multifrequency campaign in 1996. Preliminary analysis of the optical, ROSAT and RXTE data are presented. Strong variability on short time scales was observed. The data suggest an…

Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm…

Among active galactic nuclei, blazars show extreme variability properties. We here investigate the case of the BL Lac object S4 0954+65 with data acquired in 2019-2020 by the Transiting Exoplanet Survey Satellite (TESS) and by the Whole…

We present results from an original observational campaign comprising five epoch optical photopolarimetrical observations of the BL Lac-type AGN OJ287 in the period 2012 November - 2013 April. The data are gathered with the Focal Reducer…

We developed a method to separate a long-term trend from observed temporal variations of polarization in blazars using a Bayesian approach. The temporal variation of the polarization vector is apparently erratic in most blazars, while…

The long-term optical and infrared color variability of blazars has been investigated with the SMARTS monitoring data. The sample in this study consists of 49 flat spectrum radio quasars and 22 BL Lac objects. The fractional variability…

We compare the variability properties of very high energy gamma-ray emitting BL Lac objects in the optical and radio bands. We use the variability information to distinguish multiple emission components in the jet, to be used as a guidance…

We present optical identifications and radio spectra for ten radio sources from two flux-density-complete samples. Radio variability characteristics are presented for four objects. The observations were obtained on the RATAN-600 radio…

We present optical photo-polarimetric observations with high temporal resolution of the blazar AO 0235+164. Our data, the first to test the photo-polarimetric behaviour of this object at very short time-scales, show significant…

We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision…

At present three pulsars are known which clearly show a strongly increasing degree of circular polarization with frequency. As this is accompanied by a smooth decrease of linear polarization, we investigate, if this observation can be…

The BL Lac object Mrk 421 was observed in optical bands from 2009 April to 2012 May with the 1.0 m telescope at Weihai Observatory of Shandong University. Microvariability was analysed by C and F tests, but no significant microvariability…

X-ray astronomy allows study of objects which may be associated with compact objects, i.e. neutron stars or black holes, and also may contain strong magnetic fields. Such objects are categorically non-spherical, and likely non-circular when…

Polarimetry of the narrow-line radio galaxy PKS 0116+082 at the W.M. Keck telescope shows that it has high and variable optical polarization, presumably due to synchrotron radiation. It is not a BL Lac object because it has strong narrow…