Department of Astronomy
University of Michigan
Ann Arbor, MI, 48109-1042

Phone: 734 / 764-3465
Dept 734 / 764-3440
FAX: 734 /763-6317

Research Areas:

Radio emision from AGNs

Studies of gamma-ray-bright and X-ray bright AGN

Papers describing my work can be found in Selected Publications and Preprints.

My cv in pdf format can be found at CV

Examples from the UMRAO Circular Polarization Program:

Left: Monthly-averaged total flux density and circular polarization for 3C 345. Note the change in polarity in circular polarization during the early 1980s (top panel). Right: Weekly averages of the UMRAO data since 2005.0 for the very bright southern QSO OV-236. The top panel shows fractional circular polarization (Stokes V), the middle two panels show the linear polarization, and the bottom panel shows the total flux density. The amplitude of Stokes V in this source has ranged from 1 percent (unusually high for an AGN) to 0 percent. Contrary to the behavior we are finding in most of our program sources, the same sign of Stokes V (negative) has persisted for more than two decades and throughout many individual outbursts. Gaps in the data trains, most obvious at 4.8 GHz, correspond to times when the source is too near to the sun for observation.

Light curves showing 2-week averages for selected sources are now available on the Department of Astronomy web site under Facilities (Data Sets) If you need data for additional sources, please contact me at

Go to the Astronomy Department homepage.