The data from standard stars appearing in this work are the result of the best quality images obtained in April-September 1997 (approximately 54 nights in total, average of 30 observations per window), reduced and processed according to the "global" procedures discussed in Sect. 2. Some stars preliminary selected as standards were in fact eliminated after the end of 1997 campaign because they did not fully satisfy the selection criteria in the long run. We note that all these standards are being observed daily (whenever observational conditions are satisfactory) as a byproduct of our monitoring programme, and therefore the results of our catalogues are continuously being improved. Upgraded versions and the finding charts of the catalogues can be requested electronically.
Acknowledgements
We would like to thanks the financial support by FAPESP, CAPES, CNPq, Bordeaux Observatory and IAG/USP, R.D.D da Costa and the referee, F. Mignard, for useful suggestions that helped to improve the first version of the present work.
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