On the atmospheric limitations of ground-based submillimetre astronomy using array receivers
نویسندگان
چکیده
The calibration of ground-based submillimetre observations has always been a difficult process. We discuss how to overcome the limitations imposed by the submillimetre atmosphere. Novel ways to improve line-of-sight opacity estimates are presented, resulting in tight relations between opacities at different wavelengths. The submillimetre camera SCUBA, mounted on the JCMT, is the first large-scale submillimetre array, and as such is ideal for combating the effects of the atmosphere. For example, we find that the off-source pixels are crucial for removing sky-noise. Benefitting from several years of SCUBA operation, a database of deep SCUBA observations has been constructed to better understand the nature of sky-noise and the effects of the atmosphere on instrument sensitivity. This has revealed several results. Firstly, there is evidence for positive correlations between sky-noise and seeing and sky-noise and sky opacity. Furthermore, 850-μm and 450-μm sky-noise are clearly correlated, suggesting that 450-μm data may be used to correct 850-μm observations for sky-noise. Perhaps most important of all: if off-source bolometers are used for sky-noise removal, there is no correlation between instrument sensitivity and chop throw, for chop throws out to 180 arcsec. Understanding the effects of submillimetre seeing is also important, and we find that the JCMT beam is not significantly broadened by seeing, nor is there an obvious correlation between seeing and pointing excursions.
منابع مشابه
A worldwide comparison of the best sites for submillimetre astronomy
Over the past few years a major effort has been put into the exploration of potential sites for the deployment of submillimetre (submm) astronomical facilities. Amongst the most important sites are Dome C and Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In this context, we report on measurements of the sky opacity at 200 μm over a period of three years at the French-Italia...
متن کاملAn Optical Array Receiver for Deep-Space Communication through Atmospheric Turbulence
The theoretical foundations of an optical array receiver consisting of relatively small telescopes are developed and analyzed. It is shown that optical array receivers can be designed to perform as well as a large single-aperture receiver on the ground, while enjoying significant advantages in terms of operational reliability, ease of future expansion to achieve greater capacity, and further ad...
متن کاملLarge-eddy simulation of turbulent flow over an array of wall-mounted cubes submerged in an emulated atmospheric boundary-layer
Turbulent flow over an array of wall-mounted cubic obstacles has been numerically investigated using large-eddy simulation. The simulations have been performed using high-performance computations with local cluster systems. The array of cubes are fully submerged in a simulated deep rough-wall atmospheric boundary-layer with high turbulence intensity characteristics of environmental turbulent fl...
متن کاملSite testing for submillimetre astronomy at Dome C, Antarctica
Aims. Over the past few years a major effort has been put into the exploration of potential sites for the deployment of submillimetre astronomical facilities. Amongst the most important sites are Dome C and Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In this context, we report on measurements of the sky opacity at 200 μm over a period of three years at the French-Italian ...
متن کاملSubmillimetre/TeraHertz Astronomy at Dome C with CEA filled bolometer array
Submillimetre/TeraHertz (e.g. 200, 350, 450 μm) astronomy is the prime technique to unveil the birth and early evolution of a broad range of astrophysical objects. A major obstacle to carry out submm observations from ground is the atmosphere. Preliminary site testing and atmospheric transmission models tend to demonstrate that Dome C could offer the best conditions on Earth for submm/THz astro...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2002