We have used an Imaging Fabry-Perot Spectrophotometer with the Sub-arcsecond Imaging Spectrograph on the Canada-France-Hawaii Telescope to measure velocities for 1534 stars in the globular cluster M15 ( NGC 7078 ) with uncertainties between 0.5 and 10 km~ { } s ^ { -1 } .
Combined with previous velocity samples , the total number of stars with measured velocities in M15 is 1597 .
An average seeing of 0.8 \arcsec allowed us to obtain velocities for 144 stars within 10 \arcsec of the center of M15 , including 12 stars within 2 \arcsec .

The velocity dispersion profile for M15 remains flat at a value of 11 km~ { } s ^ { -1 } from a radius of 0.4 \arcmin into our innermost reliable point at 0.02 \arcmin ( 0.06 pc ) .
Assuming an isotropic velocity dispersion tensor , this profile and the previously-published surface brightness profile can be equally well represented either by a stellar population whose M/L varies with radius from 1.7 in solar units at large radii to 3 in the central region , or by a population with a constant M/L of 1.7 and a central black hole of 1000 { M } _ { \odot } .
A non-parametric mass model that assumes no black hole , no rotation , and isotropy constrains the mass density of M15 to better than 30 % at a radius of 0.07 parsecs .
The mass-density profile of this model is well represented by a power law with an exponent of –2.2 , the value predicted by models of cluster core-collapse .
Using the assumption of local thermodynamic equilibrium , we estimate the present-day mass function and infer a significant number of 0.6–0.7 { M } _ { \odot } objects in the central few parsecs , 85 % of which may be in the form of stellar remnants .

Not only do we detect rotation ; we find that the position angle of the projected rotation axis in the central 10 \arcsec is 100 ^ { \circ } different from that of the whole sample .
We also detect an increase in the amplitude of the rotation at small radii .
Although this increase needs to be confirmed with better-seeing data , it may be the result of a central mass concentration .