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During four years, systematic observations have been conducted in drift scan mode with the Bordeaux automated meridian circle in the declination band $+11\degr \leq \delta \leq +18\degr$. The resulting astrometric catalog includes about $2.3\times 10^6$ stars down to the magnitude limit $V_{\rm M}=16.3$. Nearly all stars (96% ) have been observed at least 6 times, the catalog being complete down to $V_{\rm M}=15.4$. The median internal standard error in position is ${\sim} 35$ mas in the magnitude range $11 α instead of 82 mas deduced from the model-based standard errors given in the catalog.

In this paper, all the light-curves obtained during the PHEMU91 campaign of observations of the mutual phenomena of the Galilean satellites are presented. These observations give accurate astrometric positions of major interest for dynamical studies of the motion of the Galilean satellites. The aim of this work is to give obser- vational data directly usable for theoretical studies. We made 374 observations of 111 mutual events from 56 sites. The corresponding data are given in this paper 1 . The accu- racy of each observation has been deduced from a compar- ison with the theoretical predictions. For each observation, information is given about the telescope, the receptor, the site and the observational conditions.

We present a versatile digital autocorrelation spectrometer designed to suit the needs of HIFI, the sub-millimeter heterodyne instrument of the ESA's FIRST satellite. This spectrometer will offer a set of three observation modes with different `on-line resolution/total band-width' combinations (82 kHz/500 MHz, 163 kHz/1 GHz and 325 kHz/2 GHz). An original architecture based on mixed Gallium Arsenide and Silicon technologies, allowed us to realize a 1024 channel, low power consumption and high speed correlation module: 4 mW per channel at 550 MHz clock frequency. A prototype spectrometer has been developed. It includes a 2 X 250 MHz Image Rejection Mixer, a 500 MHz clock frequency analogue to digital converter, and two 1024 channel digital correlators. This model has been integrated and tested (in laboratory and on telescope). We expose these test results.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A rst CCD 512 512 camera working in scan mode (declination eld 14 0 ) was mounted in 1994 on the Bordeaux CCD meridian circle. After a test- ing period, this camera was installed on the Valinhos CCD meridian circle (near S~ ao Paulo, Brazil), as part of a collaboration between Bordeaux Observatory and the Instituto Astronomico e Geosico of S~ ao Paulo. A sec- ond improved CCD 1024 1024 camera, with a decli- nation eld of 28 0 , was installed on the Bordeaux in- strument in June 1996. The mean internal precision of a single observation is about 0:04 00 in both coor- dinates for 9 V 14. In the same magnitude range, magnitudes can also be obtained with an in- ternal precision of about 0.05 mag. Both instruments can participate eciently in extending the Hipparcos- Tycho frame, during the next decade. Among other du- ties, the Bordeaux CCD meridian circle is being used since January 1997 for completing the M eridien 2000 project. The characteristics of both instruments and some results obtained with them are presented in this paper.