About the Gauss Portrait
The scan shows the best known portrait of Carl Friedrich Gauss. The original of this portrait was painted in 1840 by the Danish artist Christian Albrecht Jensen (1792 - 1870) for the Pulkovo observatory*, where it is still at present.
In 1840 Christian Albrecht Jensen reproduced this painting for Professor B.J. Listing, for Professor W. Weber, and for Professor W.S. von Waltershausen.
The Gauss portrait shown is a scan of the painting copied for Professor Listing. It was bought on December 29, 1883 by the National Gallery Berlin from Mrs. Professor Listing and was donated to the Prussian Academy of Science by the "Ministerium der geistlichen, Unterrichts- und Medicinalangelegenheiten" on October 13, 1888. It is now owned by the Berlin-Brandenburg Academy of Sciences and Humanities (BBAW). The BBAW holds the copyright on the scan of the portrait.
A first restoration of the picture was done in 1945, a major restoration in 1988 by the restorer Bernd Dombrowski, Berlin.
Göttingen University, where Gauss spent most of his scientific life, also owns a copy of the Gauss portrait. It was painted in 1887 by G. Biermann and most likely reproduced from Professor Weber's copy.
The last German 10 DM bill (before the Deutsche Mark was replaced by the EURO) shows an image of Gauss. It is a mirror-inverted and simplified copy of the Jensen portrait. The medal presented to the Gauss Prize awardees has also been modelled after this portrait.
Footnote: *Pulkovo is a village close to St. Petersburg (Russia). Its observatory was opened in 1839; today it hosts the Central Astronomical Observatory of the Russian Academy of Sciences. The first director of this observatory was the well-known astronomer Friedrich Georg Wilhelm Struve who was succeeded by his son Otto Wilhelm, see here. The brains of famous scientists seem to have special appeal. Göttingen University keeps the brain of Carl Friedich Gauss. If you want to learn more about it, please follow this link