Hyperfine structure investigation of spectral lines of the praseodymium atom in the visible spectral region

26 new energy levels (7 of even, 19 of odd parity) of Pr I were discovered using laser induced fluorescence (LIF) spectroscopy. Values of the magnetic hyperfine interaction constants A of these levels are presented. 57 known but up to now unclassified lines could be classified as transitions to the new levels. Moreover, 77 lines which were never mentioned in the literature but could be identified in our FT spectra, are classified. Finally, 62 other lines could be detected either as excitation or fluorescence channels, but too weak to appear in the FT spectra. For some lines the classification given in the literature appeared to be erroneous.