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J. M. Attridge (MIT Haystack Observatory), A. Greve (IRAM), T. P. Krichbaum (MPIfR)
VLBI polarization observations provide information about the structure, orientation, and evolution of the magnetic field in synchrotron emitting sources such as AGN. VLBI observations at centimeter wavelengths have shown that polarized relativistic shocks in radio jets appear as superluminal knots. In addition, magnetic field structures in the jets of BL Lacertae objects and quasars are quite different (e.g. Wardle et al. 1994, Ap.J., 437, 122; Cawthorne et al. 1993, Ap.J., 416, 519).
Millimeter VLBI observations have the advantage of being relatively unaffected by Faraday rotation and opacity (Wardle et al. 1996, in the proceedings from the Millimeter-VLBI Science Workshop held at MIT). The high angular resolution provided by millimeter VLBI observations will allow new outbursts which feed the radio jets to be observed near to their point of origin.
CMVA data of the quasars 3C273 and 3C279 taken in April 1997 by Krichbaum, et al. are being used to develop and test a data calibration path for dual-polarization data which mimics the one presented for centimeter wavelengths in NRAO's AIPS software package. Here we present the current status of the calibration efforts, as well as preliminary results on 3C273 and/or 3C279.
CMVA research at Haystack is sponsored by the National Science Foundation.