Submillimetre and Millimetre Mapping Using Interference Filters

Abstract

During the last ten years much consideration, especially at conference discussions, has centred on the relative advantages of transform interferometry as opposed to filters for astronomical measurements in the far-infrared wavelength range. The advantages of the use of ground based sites as opposed to balloon or rocket-borne platforms have also been discussed. Of the four possible combinations thus presented, three have recently been used successfully whilst the remaining possibility may well produce results in the very near future. Thus rocket and balloon borne filter instruments have been used by McNutt et al. [1], Harwit et al. [2], and Hoffmann et al. [3] to investigate the microwave background and map the galactic centre. Ade et al. [4] have used filters for solar mapping from ground-based sites. The use of transform interferometry has up to the present been less successful in respect of submillimetre astrophysical results. Nolt, using a ground-based site has detected an emission line centred at 11.7 cm⁻¹ which could be of extraterrestrial origin whilst successful balloon- or rocket-borne transform interferometry is still awaited.