The density profile of 47 Tucanae

We have used high-resolution HST-WF/PC images of the core of the globular cluster 47 Tucanae in the U-band to determine its radial density profile. The exceptional photometric quality of the data set ensures highly reliable measurements since no photometric completeness correction is required for stars at and above the turn-off luminosity over the whole field. The position of the center of gravity of the duster is found to agree very well with that provided by previous FOC observations but differs by similar to 6 '' from the position of the luminosity center as measured from the ground. Within the similar to 40 '' radius of the cluster center sampled by this data set, the density distribution of stars with masses greater than or similar to 0.85 M. is well fitted by a King-type profile with r(c) similar or equal to 12.'' 2 +/- 2.'' 1. Values of r(c) larger than similar to 15 degrees are not compatible with the data and therefore are at variance with those obtained by both ground-based (r(c) similar or equal to 25 degrees) or previous WF/PC studies (r(c) similar or equal to 23 ''), We show that the discrepancy with earlier results can be ascribed entirely to the effects of photometric incompleteness.