  $Context.$ The YSO Th 28 possesses a highly collimated jet, which clearly
exhibits an asymmetric brightness of its jet lobes at optical and NIR
wavelengths. There may be asymmetry in the jet plasma parameters in opposite
jet lobes (e.g. electron density, temperature, and outflow velocity). $Aims.$
We examined the Th 28 jet in a 3"x3" where the jet material is collimated and
accelerated. Our goal is to map the morphology and determine its physical
parameters to determine the physical origin of such asymmetries. $Methods.$ We
present $JHK$-spectra of Th 28 obtained with the SINFONI on the (VLT, ESO) in
June-July 2015. $Results.$ The [Fe II] emission originates in collimated jet
lobes. Two new axial knots are detected at 1" in the blue lobe and 1".2 in the
red lobe. The H$_2$ radiation is emitted from an extended region with a radius
of $\gtrsim270$ au, which is perpendicular to the jet. The PV diagrams of the
bright H$_2$ lines reveal faint H$_2$ emission along both jet lobes as well.
The compact and faint H I emission (Pa$\beta$ and Br$\gamma$) comes from two
regions, namely from a spherical region around the star and from the jet lobes.
The size of the jet launching region is derived as 0".015 ($\sim$3 au at 185
pc), and the initial opening angle of the Th 28 jet is $\sim28^0$, which makes
this jet substantially less collimated than most jets from other CTTs.
$Conclusions.$ The emission in [Fe II], H$_2$, and H I lines suggests a
morphology in which the ionised gas in the disc appears to be disrupted by the
jet. The resolved disc-like H$_2$ emission most likely arises in the disc
atmosphere from shocks caused by a radial uncollimated wind. The asymmetry of
the [Fe II] photocentre shifts with respect to the jet source arises in the
immediate vicinity of the driving source of Th28 and suggests that the observed
brightness asymmetry is intrinsic as well.
