Proceedings of the Particle Physics and Early Universe Conference (PPEUC).
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4 The 96--97 mission 

The observing strategy is studied to obtain a map of CMBR anisotropies in a circular strip around the South Celestial Pole. Details can be found in (Piccirillo et al. (1997)). The main idea is to observe at the local zenith, allowing the sky to move on the experiment in drift-scan mode. The wobbling direction is chosen to scan a region of around each R.A. Raw data are analysed by performing a lock-in deconvolution of the first six harmonics of the modulation frequency. It is therefore possible to obtain a pixelized map of the observed regions. Moreover, one of the high frequency channel is devoted to the subtraction of residual atmospheric emission. This is obtained by comparing its signal to the others, and performing a correlation analysis.

The first observing campaign took place in December 1996--January 1997 at Dome C. The experiment was first assembled at Terra Nova Bay station, where cryogenics fluids were also produced. APACHE96 was then brought at Dome C and assembled, along with the outer solar shield. Calibrations have been obtained in situ and PWV was also monitored during observations.

During this first mission the observed sky region included regions of low galactic latitude, to calibrate observations by correlating our results with the emission of the Galactic plane observed in satellite missions (COBE-DIRBE, Wright (1991); IRAS, IRAS Explanatory Suppl. (1994)). We obtained more than 100 hours of useful observations, with a satisfying behaviour of the experiment. Average temperature was around and average Precipitable Water Vapour .

A first analysis of raw data shows that the sky-noise in the lower frequency channels has a flat power spectrum. This is an interesting indication of the good observing conditions at Dome C (Wilkinson (1997)).

PPEUC Proceedings
Tue Jul 22 18:51:17 BST 1997