I am practising some exam questions for a radio interferometry exam, and I am struggling with this question:

The physical size of a single LOFAR station, operating at 150MHz is about 50m. Estimate the number of pixels which would be needed to map the full primary beam if one wished to include all LOFAR stations (maximum baseline ~ 800 km) at full resolution.

OK, so the resolution of the entire array is given by

Wavelength / Baseline Length which is 2m/800km = 2.5 x 10^-6 radians, or 0.52 arcseconds.

I don't know how to relate this angular resolution to the image size which I think is a 50m square.

Can anyone help with this?

  • $\begingroup$ I think you need to know the distance to the 50m square to find its angular dimensions, and divide them by the angular resolution... $\endgroup$
    – Tosic
    Jan 13, 2019 at 14:25


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