Centimeter Band Observations of Circular Polarization in Flaring Blazars from the Effelsberg and Michigan Programs
Abstract
A program to study the centimeter-band spectral variability in Stokes V with the Michigan 26-meter radio telescope (Astrophys. Sp. Sc., 288, 17, 2003) has provided evidence for polarity changes and wavelength-dependent variability; this work has been restricted to time-averaged data for a small subset of strong sources because of the low levels of circularly polarized emission. A new calibration technique has recently been developed which yields high-accuracy full-Stokes data from measurements obtained with the Effelsberg 100-m radio telescope (Astron. Astrophys., 498, 591, 2009). This capability is important since it permits study of Stokes V emission from a wide range of sources and a search for variations on rapid time scales. As a test of the achieved accuracy, we have compared coeval 5 GHz measurements obtained in 2007 from the two radio telescopes. We present multi-epoch data for three program sources -- 3C84, 3C279, and 2145+067 -- which illustrate that excellent agreement in polarity and amplitude is attained.
UMRAO is supported in part by NSF grant AST-0607523 and by funds from the University of Michigan. E. C. is supported by a grant from the EU Framework 6 Marie Curie Early Training Programme under contract MEST-CT-2005-19669``ESTRELA''.- Publication:
-
American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21543422A