Editing 4 Vesta (section)

==Coordinate systems==
Two longitudinal coordinate systems are used for Vesta, with [[prime meridian]]s separated by 150°. The [[IAU]] established a coordinate system in 1997 based on ''Hubble'' photos, with the prime meridian running through the center of [[Olbers Regio]], a dark feature 200&nbsp;km across. When ''Dawn'' arrived at Vesta, mission scientists found that the location of the pole assumed by the IAU was off by 10°, so that the IAU coordinate system drifted across the surface of Vesta at 0.06° per year, and also that Olbers Regio was not discernible from up close, and so was not adequate to define the prime meridian with the precision they needed. They corrected the pole, but also established a new prime meridian 4° from the center of [[Claudia (crater)|Claudia]], a sharply defined crater 700 meters across, which they say results in a more logical set of mapping quadrangles.<ref name="Claudian"/> All NASA publications, including images and maps of Vesta, use the Claudian meridian, which is unacceptable to the IAU. The IAU Working Group on Cartographic Coordinates and Rotational Elements recommended a coordinate system, correcting the pole but rotating the Claudian longitude by 150° to coincide with Olbers Regio.<ref name="IAUcoordinates"/> It was accepted by the IAU, although it disrupts the maps prepared by the ''Dawn'' team, which had been positioned so they would not bisect any major surface features.<ref name=Claudian/><ref name="Dawncoordinates"/>