Long – term performance evaluation of a fixed and solar follow – up systems with modified astronomical positioning in Polish conditionsArtur Bugała, Grażyna Frydrychowicz – Jastrzębska, Zbyszek Zbytek, Jacek Dach and Damian JanczakMATEC Web of Conferences, 59 (2016) 03004DOI: https://doi.org/10.1051/matecconf/20165903004