Context : Kanzelhöhe Observatory for Solar and Environmental Research ( KSO ) provides daily multispectral synoptic observations of the Sun using several telescopes .
In this work we made use of sunspot drawings and full disk white light CCD images .

Aims : The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964 - 2016 , using the KSO sunspot drawings and white light images .
We also compare the differential rotation parameters derived in this paper from the KSO with those collected fromf other data sets and present an investigation of the north - south rotational asymmetry .

Methods : Two procedures for the determination of the heliographic positions were applied : an interactive procedure on the KSO sunspot drawings ( 1964 - 2008 , solar cycles nos .
20 - 23 ) and an automatic procedure on the KSO white light images ( 2009 - 2016 , solar cycle no .
24 ) .
For the determination of the synodic angular rotation velocities two different methods have been used : a daily shift ( DS ) method and a robust linear least-squares fit ( rLSQ ) method .
Afterwards , the rotation velocities had to be converted from synodic to sidereal , which were then used in the least-squares fitting for the solar differential rotation law .
A comparison of the interactive and automatic procedures was performed for the year 2014 .

Results : The interactive procedure of position determination is fairly accurate but time consuming .
In the case of the much faster automatic procedure for position determination , we found the rLSQ method for calculating rotational velocities to be more reliable than the DS method .
For the test data from 2014 , the rLSQ method gives a relative standard error for the differential rotation parameter B that is three times smaller than the corresponding relative standard error derived for the DS method .
The best fit solar differential rotation profile for the whole time period is \omega ( b ) = ( 14.47 \pm 0.01 ) - ( 2.66 \pm 0.10 ) \sin ^ { 2 } b ( deg/day ) for the DS method and \omega ( b ) = ( 14.50 \pm 0.01 ) - ( 2.87 \pm 0.12 ) \sin ^ { 2 } b ( deg/day ) for the rLSQ method .
A barely noticeable north - south asymmetry is observed for the whole time period 1964 - 2016 in the present paper .
Rotation profiles , using different data sets , presented by other authors for the same time periods and the same tracer types , are in good agreement with our results .

Conclusions : The KSO data set used in this paper is in good agreement with the Debrecen Photoheliographic Data and Greenwich Photoheliographic Results and is suitable for the investigation of the long-term variabilities in the solar rotation profile .
Also , the quality of the KSO sunspot drawings has gradually increased during the last 50 years .