Atacama Large Millimeter Array 183 GHz Radiometer

To measure the precipitable water vapour, Onsala Space Observatory and the The Cavendish Astrophysics Group at the University of Cambridge had designed and built two 183 GHz radiometers . These radiometers measure the brightness temperature in three bands close to the 183 GHz water line. These bands are: 1.2 GHz, 4.1 GHz and 7.6 GHz away from the water line centre. During data reduction we iterate on the water vapour density in the radiative transfer equation to obtain the amount of precipitable water vapour producing the sky brightness temperature measured by the 183 GHz radiometer.

The radiometers are located at the ends of the 300 m baseline of the site testing interferometers available in Chajnantor. The idea of installing radiometers at the ends of the interferometer baseline is to compare the radiometric phase correction versus the interferometric phase correction methods.

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Description of the equipment

Victor Belitsky and Denis Urbain, from the Group for Advance Receiver Development (OSO) , have prepared a webpage with a technical description of the 183 GHz radiometers.

Data Available

2002

2001