Inspector of the Grand Gallery at the Sans Souci Castle in Potsdam from 1757.
Oesterreich waited on Boswell at his lodgings in Potsdam on July 4, 1764, and “carried him in a coach to the Retreat of the Great Frederic [i.e. Sans Souci]”, where he gave him a tour of the castle and its impressive gallery.
Oesterreich compiled several catalogues of the works in the possession of Frederick the Great, some of which are available in various editions via AbeBooks today. These include Beschreibung der Königlichen Bildergallerie und des Kabinets im Sans Souci (1764), Beschreibung der Neuen Kammern in Sanssouci (1775) and Beschreibung und Erklärung der Grupen, Statuen, ganzen und halben Brust- Stücke, Basreliefs, Urnen und Vasen von Marmor, Bronze und Bley, sowohl von antiker als moderner Arbeit, welche die Sammlung Sr. majestät, des Königs von Preußen, ausmachen (1775).