Optical structure of the core of the dynamically advanced globular cluster NGC 6397

It is noted that the old globular cluster NGC 6397 has a short central relaxation time (2 x 10 to the 7th yr) and is dynamically very advanced. Its proximity to the sun (about 2.4 kpc) makes its core a favorable target for observers. Long focus bidimensional observations at ESO, combined with data that are already available, make possible the detection and photometric study of a central clump of faint stars similar to the central condensation in M 15. It is noted that this luminosity cusp is nearly two times smaller in size and about 10 times fainter than that of M 15. Each cusp corresponds to approximately 0.006 of the total brightness of the entire corresponding cluster. It is thought that the cusps may be related to the 'central singularity' which is expected to occur in globular cluster cores.