8 Conclusions

By upgrading the Carlsberg Meridian Telescope to have a CCD operating in drift-scan mode, a new lease of life has been breathed into the telescope. It should be pointed out that this will only be useful over the next ten years or so. Then, data from astrometric satellites such as DIVA and GAIA will become generally available and supersede the astrometric accuracy of what can be achieved from the ground. It is thus important that planned upgrades of meridian telescopes are carried out as soon as possible and that the results are published promptly so that the maximum use can be made of the data.

The results shown here demonstrate that using transfer functions it is possible to calibrate the fluctuations caused by atmospheric turbulence using just the Tycho 2 stars. This is a more efficient method than using a subcatalogue since multiple measurements of the sky are not required.

After this calibration, the external accuracy achieved for the brightest stars in the survey is 36 mas in right ascension and declination and 0.025 mag in $r'_{\rm CMT}$ photometry.

The web site of the telescope is at:
http://www.ast.cam.ac.uk/~dwe/SRF/camc.html

Acknowledgements

We thank Bob Argyle, Claus Fabricius, Ole Einicke, Anton Sørensen, Jens Klougart. Niels Michaelsen, Torben Knudsen, Jose Muiños, Fernando Belizón and Miguel Vallejo for useful and helpful discussions and advice.

The Institute of Astronomy personnel are part of the Cambridge Astronomical Survey Unit which is funded by the Particle Physics & Astronomy Research Council of the UK.

The Danish participation in the project has been funded by the Copenhagen University Observatory. The Carlsberg Foundation provided financial support for the initial CCD development.

Thanks are due to Jean-François Le Campion and Michel Rapaport, Bordeaux, and Norbert Zacharias, USNO, for early release of data.