A warning on the determination of the halo mass
  We summarize our studies on the determination of the mass of the dark matter halo, based on observations of rotation curves of test particles or of the gravitational lensing. As we show, it is not uncommon that some studies on the nature of dark matter include extra assumptions, some even on the very nature of the dark matter, what we want to determine!, and that bias the studies and the results obtained from the observation and, in some cases, imply an inconsistent system altogether. 
Dario Nunez, Alma X. Gonzalez Morales, Jorge L. Cervantes-Cota,   Tonatiuh Matos
astro-ph.GA gr-qc