Interferometers with Complete Coverage of Rectangular Domains in the U,V-Plane

Abstract

The systems of linear aperture synthesis considered in Chapter 1 enable obtaining full maps of astronomical objects merely when observations of prolonged periods, not shorter than 12 hours, are made. Although these systems provide a high resolution while having a comparatively small number of elements (aerials), they cannot be used in many cases. First, this relates to the study of sources with nonstationary parameters (i.e. altering in time). Second, linear systems are not suitable in the case when observation of many objects in a wide field of view is to be carried out whereas the observing time is limited. Because of the afore-said, the interferometers which allow synthesizing the image of an object in a single exposure (in so-called snapshot regime) are widely employed. Clearly, such systems must be two-dimensional, with a high resolution in the both coordinates. When using two-dimensional (2-D) interferometers, the exposure time is defined by the required signal-to-noise ratio only. If the aerials functioning in the system are sufficiently large and effective, the exposure time may be short enough.