Hallo Leute,
die Auflösung der Verwirrung findet sich in dieser schönen Arbeit, die eine Zeichnung von Encke aus dem Jahr 1837 wiedergibt:
http://www.astrosurf.com/re/en…ision_saturn_2017_PRe.pdf
Zitat:
"In 1837 Johann Franz Encke, director of the Berlin observatory, using a 246 mm refractor observed a dark “minimum” of intensity on the northern face of ring A and obtained micrometre measures of its position (Figure 6).
William Lassel and William Dawes (1843) observed the Encke minima with a 9-inch refractor and another division near the edge of ring A (Figure 7). Dawes described these observations:
Having obtained a fine adjustment of the focus, I presently perceived the outer ring to be divided into two. This coincided with the impression Mr. Lassell had previously received (...) With 400x the secondary division was perceptible during occasional best views of the planet. occasionally, for several seconds together,I had by far the finest view of Saturn that I was ever favoured with. Theoutlineof the planet was very hard and sharply defined with power 450x and the primary (Cassini’s) division very black and steadily seen all round the southern side. When this was most satisfactorily observed, a dark line was pretty obvious on the outer ring. I was not only perfectly satisfied of its existence, but had time during the best views carefully to estimate its breadth, in comparison with that of the division ordinarily seen (...) It is certainly rather outside the middle of the outer ring, and is broadest at the major axis, being in this respect precisely similar to the primary division. It was equally visible at both ends of the ring. "
Also ist das historische Encke-Minimum - von Encke selbst beobachtet - das Intensitätsminimum in der Mitte des A-Rings.
Die Encke-Teilung dagegen wurde erstmals 1843 von Lassel und Dawes gesichtet.
Gruß Lars
PS: Habe mir gerade in Stellarium die Situation von 1837 angeschaut. Saturn war Anfang Mai in Opposition bei einer Deklination von -13,5 Grad. Das bedeutet, der gute Encke in Berlin hatte kaum Chancen, die später nach ihm benannte Teilung selbst zu entdecken....