  Follow-up imaging observations of the first detected interstellar comet
2I/Borisov are presented, which were carried out with the
Schmidt-Teleskop-Kamera at the University Observatory Jena in 11 observing
epochs in October and November 2019. The orbital solution of the comet, derived
from the obtained astrometric measurements, confirms its highly eccentric
($e=3.3570 \pm 0.0006$) and inclined ($i=44.0524 \pm 0.0004\,^\circ$) orbit,
that proves the interstellar origin of the comet. According to our best-fitting
orbital solution, comet 2I/Borisov reaches its perihelion on 2019 Dec 8
($q=2.0066$ au) and its closest encounter with Earth on 2019 Dec 28
($\Delta_{\text{min}}=1.9368$ au). The distance corrected brightness of the
nucleus of the comet clearly exhibits a linear correlation with its phase
angle. The slope of this correlation indicates the activity of the comet, which
is also detected in deep imaging data, taken in 5 observing epochs, showing the
coma and the tail of the comet. During our observing campaign the coma of comet
2I/Borisov exhibits on average a diameter of $(4.57\pm0.38) \cdot 10^4$ km, and
the length of the tail of the comet measures $(1.52\pm0.12) \cdot 10^5$ km,
assuming an anti-solar orientation.
