A mass vs angle from the sky plane (ξ) from three simultaneous images of the same CME, observed on 12 December 2008 at 12:27UT, from SOHO/LASCO-C2 (green), and STEREO-A/COR2 (red) and -B/COR2 (blue) (C. de Koning, private communication, 2014). The failure of these three plots to intersect at a common point (supposedly representing the “true” location and mass of the CME) demonstrates a possible inadequacy in the calibration of one or more of these coronagraphs.