Instrumental Requirements for AGN Continuum Studies



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Instrumental Requirements for AGN Continuum Studies

The critical instrumental parameters for AGN continuum studies are a combination of the angular resolution to determine the distributions of total and polarized intensity within jets, around hot spots, and in the lobe filaments of powerful sources, combined with enough sensitivity to image the polarized emission. The need for accurate polarimetry of features that may be intrinsically faint or even beamed away from us by relativistic bulk motion drives the demand for sensitivity. Wide bandwidths are not by themselves a panacea for sensitive imaging and polarimetry at the lower frequencies because of bandwidth smearing, Faraday rotation, and RFI. Most wide-band continuum imaging and polarimetry at low frequencies will be done in a spectral-line mode and will need the expanded correlator capabilities.

This arena also benefits greatly from the increased resolution offered at all frequencies by the A+ configuration, and from cross-linking with the VLBA. 0.6 GHz and 2.4 GHz systems will be particularly important for imaging spectral gradients and curvature, and for polarimetry. The E configuration and very low frequencies are relatively less important, though not irrelevant.



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