The direction of the north pole and the control network of asteroid 243 Ida

A control network containing 64 points identified on Galileo images obtained during the August 1993 flyby was used to determine the direction of Ida's north pole. We find the right ascension and declination (in J2000 coordinates) to be [[Alpha].sub.0] = 348.76 [degrees] [+ or -] 7.5 [degrees], [[Delta].sub.0] = 87.10 [degrees] [+ or -] 0.4 [degrees]. This result agrees reasonably well with earlier determinations from groundbased observations of Ida's lightcurve. We confirm that the rotation is retrograde, but we lack the time base to improve the rotation period of 0.1930680 days determined from lightcurve analysis (Binzel, R. P., S. M. Sivan, P. Magnusson, W. Z. Wisniewski, J. Drummond, K. Lumme, M. A. Barucci, E. Dotto, C. Angeli, D. Lazzaro, S. Mottola, M. Gonano-Beurer, T. Michalowski, G. De Angelis, D. J. Tholen, M. Di Martino, M. Hoffmann, E. H. Geyer, and F. Velichko 1993. Icarus 105, 310-325).