Friedrich Wilhelm Bessel was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method of parallax. Certain important mathematical functions were named Bessel functions after Bessel's death, though they had originally been discovered by Daniel Bernoulli before being generalised by Bessel.
C. A. Jensen, Friedrich Wilhelm Bessel, 1839 (Ny Carlsberg Glyptotek)
Königsberg Observatory (1830)
Tabulae Regiomontanae reductionum observationum astronomicarum ab anno 1750 usque ad annum 1850 computatae, 1830
Heinrich Wilhelm Matthias Olbers
Heinrich Wilhelm Matthias Olbers was a German astronomer. He found a convenient method of calculating the orbit of comets, and in 1802 and 1807, discovered the second and the fourth asteroids Pallas and Vesta.
Lithograph by Rudolph Suhrlandt
Olbers monument in Bremen by Carl Johann Steinhäuser (1850)
Abhandlung über die leichteste und bequemste Methode die Bahn eines Cometen zu berechnen, 1797