The interferometric extended source sensitivity

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The interferometric extended source sensitivity

The name of interferometric “extended” source sensitivity can be misleading. Indeed, the notion of noise for an extended source depends on the source shape. For instance, a flat source of infinite extent would be measured through the visibility exactly located the phase center, and all other visibilities would only show noise. In this thought experiment the noise level on the constant brightness would thus be the noise of a single visibility! More generally, if we take a Gaussian source of a given FWHM, only the visibilities located inside a radius of a few time would contribute the the flux measurement of that Gaussian, and the other visibilities would just be noise.

So the only well defined “extended” source sensitivity is the sensitivity for a source that exactly fills the Gaussian synthesized beam. This is what we will derive in this section.

Subsections

- Yielding the interferometric extended source sensitivity
- Interpretation