Calibration of VLBI Polarization Data

Scott E. Aaron
Max-Planck-Institut für Radioastronomie & Joint Institute for VLBI in Europe

The technique of imaging the linearly polarized emission from radio sources has long been routine for instruments such as the VLA. However, at VLBI scales, such observing has been historically limited to a small group of scientists, primarily at or associated with Brandeis University. With the advent of the VLBA, interest in polarization observing has dramatically increased, both with the VLBA and with the EVN. Apart from the scientific interest in studying the linearly polarized emission from sources, polarization observing has the additional benefit for EVN observers that the significant baseline errors introduced into the total intensity data by the instrumental polarization (e.g., [Massi et al. 1997]; [Massi & Aaron 1997]) may be removed. This document is intended to provide a guide to the acquisition, processing, and imaging of VLBI polarization data.

 

• Instrumental Polarization
• Linear model
• Ellipticity-Orientation Model
• Limitations on the Correction for Instrumental Polarization
• Observational Considerations
• Instrumental Polarization Calibrator
• Position Angle Calibrator
• Data Processing
• Reading the correlator output
• MarkIII correlator
• VLBA correlator
• Antenna Phase Cal
• Correction for parallactic angle
• Fringe Fitting
• Manual Phase Cal
• Full Fringe Fitting
• Right-Left Delay Difference-CROSSPOL
• Amplitude Calibration
• Bandpass Calibration
• Applying the full calibration
• Polarization Calibration
• Applying the Instrumental Polarization Calibration
• Position Angle Calibration
• Self Calibration and Imaging
• Literatur
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