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Home > Instrumentation > LABOCA > LABOCA Calibration

LABOCA Calibration

On this page we give an overview over the various topics which are covered under "Calibration".

Intensity calibration

Pointing & Focus

Beam shape & angular resolution

From beam maps on Mars the angular size of the telescope beam was measured for individual bolometers. After deconvolution by the planet and pixel size we found:

FWHM = 18.6″ ± 1.0″

The shape of the main beam is an almost circular Gaussian. At intensities below 1% of the peak, the beam starts to deviate from a Gaussian, with the first error beam pattern at a relative intensity of 0.5%. The support structure of the subreflector becomes visible at the 0.1% level.

Array parameters

For a multi-channel receiver, the array parameters include the relative offsets of the individual channels as well as their relative gains. Both can be estimated from fully sampled maps (for all channels) on strong compact objects.
During the commissioning phase, several of these maps (so-called beam maps) were observed on the planets Mars and Saturn. After averaging, a final array parameter file was produced. These parameters are implemented in the APEX control system and in the Boa reduction software. The accuracy in position is below 1.5″ and the gain accuracy better than 5% for each bolometer.