RRI Efficient Linear-array Imager: salient aspects

Abstract

Recently, a new optics entitled Efficient Linear-array Imager [1] has been proposed to use radio receivers efficiently for imaging the skies. The new optics demonstrates that it is possible to trade instantaneous sensitivity to instantaneous field-of-view while conserving the $\mathrm{A}\Omega$ product. For a dish of size D fitted with N receivers, this product is $\sim D ^ { 2 } N$. This can be rewritten as $2 \left( D \times \frac { D } { N / 2 } \right) \times ( N / 2 ) ^ { 2 }$. The first part, $2 \left( D \times \frac { D } { N / 2 } \right)$, implies two orthogonal areas of elliptical cross section with an N/2 aspect ratio. The second part, $( N / 2 ) ^ { 2 }$, indicates the number of simultaneous beams formed with N receivers. Thus, the resultant configuration is two telescopes of elliptical cross sections laid in a cross-configuration, each fitted with N/2 receivers. Then, by cross correlating each set of receivers with the orthogonal set of receivers, one obtains the $( N / 2 ) ^ { 2 }$ beams.