1961 Austria 1.80s Stamp - 75 Years of Sonnblick Observatory

This is a rectangular postage stamp issued by the Republic of Austria ('REPUBLIK ÖSTERREICH') in 1961 to commemorate the 75th anniversary of the Sonnblick Observatory ('75 JAHRE SONNBLICK OBSERVATORIUM'). The stamp features a monochromatic design in slate-blue/grey-blue ink on off-white paper with white borders. The central image illustrates the Hoher Sonnblick peak with the observatory perched at the summit, rendered with fine cross-hatching and dot-pattern engraving. The denomination 'S 1.80' (Schilling) is positioned in the top left. Notable markings include the designer/engraver's name 'H. RANZONI D. J.' at the bottom center. The stamp is presented in a vertical orientation with standard perforations. Regarding condition, it appears to be a used specimen as evidenced by a partial black circular date stamp (CDS) or 'Wien' cancellation mark on the lower right corner. The perforations appear relatively intact, though there is a slight crease or surface mark visible near the top left corner within the dark mounting background. The item is set against a dark philatelic mount, which is placed on a light-colored grid paper. The craftsmanship reflects the mid-20th-century Austrian tradition of high-quality recessed printing (engraving).