Book contents
- Frontmatter
- Contents
- Index of Participants
- Preface
- I Evidence and Implications of Anisotropy in AGN
- II Luminosity Functions and Continuum Energy Distributions
- Radio Luminosity Functions of Active Galaxies
- The Quasar Luminosity Function
- UK ROSAT Deep & Extended Deep Surveys
- Luminosity Dependence of Optical Activity in Radio Galaxies
- Modelling the Quasar Luminosity Function in Hierarchical Models for Structure Formation
- Active Galactic Nuclei in Clusters of Galaxies
- Clustering Properties of AGNs and their Contribution to the X-ray Background
- Energy Distributions of AGN
- Absorption in the ROSAT X-ray Spectra of Quasars
- Dust in AGNs
- First Simultaneous UBVRI Photopolarimetric Observations of a Sample of Normal Quasars
- Intermediate Resolution Spectropolarimetry of Three Quasars
- Active Galaxies which Emit Strongly at 25μm
- III The Broad Line Region: Variability and Structure
- IV X-rays and Accretion Disks
- V Beams, Jets and Blazars
- VI Concluding Talk
First Simultaneous UBVRI Photopolarimetric Observations of a Sample of Normal Quasars
from II - Luminosity Functions and Continuum Energy Distributions
Published online by Cambridge University Press: 04 August 2010
- Frontmatter
- Contents
- Index of Participants
- Preface
- I Evidence and Implications of Anisotropy in AGN
- II Luminosity Functions and Continuum Energy Distributions
- Radio Luminosity Functions of Active Galaxies
- The Quasar Luminosity Function
- UK ROSAT Deep & Extended Deep Surveys
- Luminosity Dependence of Optical Activity in Radio Galaxies
- Modelling the Quasar Luminosity Function in Hierarchical Models for Structure Formation
- Active Galactic Nuclei in Clusters of Galaxies
- Clustering Properties of AGNs and their Contribution to the X-ray Background
- Energy Distributions of AGN
- Absorption in the ROSAT X-ray Spectra of Quasars
- Dust in AGNs
- First Simultaneous UBVRI Photopolarimetric Observations of a Sample of Normal Quasars
- Intermediate Resolution Spectropolarimetry of Three Quasars
- Active Galaxies which Emit Strongly at 25μm
- III The Broad Line Region: Variability and Structure
- IV X-rays and Accretion Disks
- V Beams, Jets and Blazars
- VI Concluding Talk
Summary
Abstract
We present the results from truly simultaneous UBVRI photopolarimetric observations on “normal” quasars at the Nordic Optical Telescope. Some of the observed quasars show no measurable polarization, this being consistent with previous measurements of these objects. On the other hand in PG 1008+133 and PG 1351+64 we detected low (1.5%) polarization. In PG1351+64 this polarization shows also wavelength dependence and in PG 1008+133 the position angle show wavelength dependence. These are the first such observations in these quasars.
Observations
We have selected quasars from the Veron-Cetty & Veron (1991) catalogue. The only selection criteria being: the object is bright enough to be observed in reasonable integration time. In practice this means that Vmag < 16. And that the object can be observed from La Palma, using the Nordic Optical Telescope (Declination > −30°).
The observations were made at the Nordic Optical Telescope during February 1991 and July 1992. We used the Turku photopolarimeter. This instrument gives truly simultaneous results in five (UBVRI) colour bands. A detailed description of the instrument and the observing method can be found from Takalo et al. (1992, and references therein). The total integration time depended on the object brightness, ranging from one to four hours.
Results
The main results are listed in Table 1., where we list the observed objects according to the measured polarization.
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- Chapter
- Information
- The Nature of Compact Objects in Active Galactic NucleiProceedings of the 33rd Herstmonceux Conference, held in Cambridge, July 6-22, 1992, pp. 147 - 149Publisher: Cambridge University PressPrint publication year: 1994