Measurements of the distance have elicited much controversy. Results prior to the launch of the "Hipparcos" satellite generally found that the Pleiades were about 135 parsecs (pc) away from Earth. Data from "Hipparcos" yielded a surprising result, namely a distance of only 118 pc by measuring the parallax of stars in the cluster—a technique that should yield the most direct and accurate results. Later work consistently argued that the "Hipparcos" distance measurement for the Pleiades was erroneous. In particular, distances derived to the cluster via the Hubble Space Telescope and infrared color-magnitude diagram fitting (so-called "spectroscopic parallax") favor a distance between 135 and 140 pc; a dynamical distance from optical interferometric observations of the Pleiad double Atlas favors a distance of 133 to 137 pc. However, the author of the 2007–2009 catalog of revised "Hipparcos" parallaxes reasserted that the distance to the Pleiades is ~120 pc and challenged the dissenting evidence. Recently, Francis and Anderson proposed that a systematic effect on "Hipparcos" parallax errors for stars in clusters biases calculation using the weighted mean and gave a "Hipparcos" parallax distance of 126 pc and photometric distance 132 pc based on stars in the AB Doradus, Tucana-Horologium, and Beta Pictoris moving groups, which are all similar in age and composition to the Pleiades. Those authors note that the difference between these results can be attributed to random error.