The surface of Mercury in the 210-350° W longitude range

New ground based observations of Mercury in the morning elongation were carried out under good meteorological conditions. During 20-24 November 2006, at the SAO observatory of the Russian Academy of Science (Lower Arkhiz, Karachaevo-Circassia, Russia, 41°26′E, 43°39′N), the sector of longitudes 265-350° W of Mercury was observed using the short exposures method. The sector was not covered by imaging from the spacecraft Mariner-10 in 1974-1975 or by MESSENGER at its first flyby of the planet (January 2008). One of the main tasks of new observations was acquiring a full image of the object Basin S, which was investigated earlier only in a fragmentary way due to the illumination conditions. During 20-24 November 2006 Basin S was partly or full on the lit side of the planet. By the processing of the large number of the initial electronic photos a full high resolution image of Basin S was obtained, together with other elements of the surface of Mercury in this longitude sector.