A discussion on infared astronomy - Some problems and instrumental features of submillimetre astronomy

Abstract

Modern astronomy includes optical, ultraviolet, infrared and, in recent years, also radio astronomy,y-ray and X-ray astronomy. Such a classification is justified to a certain degree. In fact, a difference in wavelength ranges necessitates a distinction in methods and techniques of receiving radiation. Also, specific problems need, for their solution, observations in different wavelength regions. In this respect it is possible to speak about a new astronomical branch—-I mean the submillimetre branch. It is known that the submillimetre range is one intermediate between infrared and microwave regions, as it is shown in table 1. The boundaries of this range are not very definite. Some authors include in the submillimetre range wavelengths longer than 50 μm, while others move this border to 100 μm. The long-wave edge of the submillimetre range is also diffuse. Formally it is a wavelength of 1 mm. But in some cases the 2 mm or 4 mm wavelengths are also ascribed to submillimetre range. The measurements of submillimetre receiver performances are sometimes carried out at wavelengths up to 8 mm. The uncertainty of the range boundaries is very understandable: their shifting depend on the methods of generation, transmission and detection of radiation.