OBSERVATIONS. F. Langenhorst, A. Deutsch, U. Hornemann, B. A. Ivanov and E. Lounejeva Bayerisches Geoinstitut (BGI), University of Bayreuth, D-95440 Bayreuth, Germany, ; Inst. f. Planetologie (IfP), University of Münster, D-48149 Münster, Germany, ; Ernst-Mach-Institut (EMI), Am Klingelberg 1, D-79588 Efringen-Kirchen, Germany, <hornem...