  In this brief note some comments about the observable used in a recently
published paper on the measurement of the general relativistic Lense-Thirring
in the gravitational field of the Earth are presented. It turns out that, among
other things, the authors might have yielded an optimistic evaluation of the
error budget because of an underestimation of the impact of the secular
variations of the even zonal harmonics of the geopotential. More realistic
evaluations point towards a 15-45% error at 1-3sigma level, respectively.
