Kärnan. Who painted it ?

Here's a really difficult one:

This small painting - oil on canvas, 19.0 cm x 13.8 cm - shows the medieval tower Kärnan in Helsingborg, Sweden. Since there's no flagpole on top of it, the painting must be from the first half of the 19th century. No signatures, no labels, no nothing.

To identify the artist you must know someting about Swedish artists at that time, but I'm sure some of you do just that !