THE MULTI-PERIODIC PULSATING PG-1159 WHITE-DWARF PG-0122+200

PG 0122+200 is a hot pulsating PC 1159 [GW Virginis] star. This paper describes the results of two, bi-site, time-series photometric observa tional campaigns. The observed complex light curve is interpreted as r esulting from a mixture of non radial g-mode pulsations. There appear to be at least ten independent frequencies in the power spectrum. The pulsation periods fall into four groups and are confined to a rather n arrow interval between 336 and 470 seconds. The frequency resolution a chieved (similar or equal to 1.1 mu Hz) reveals a fine structure which is interpreted as rotational splitting of l = 1 modes. This splitting is consistent with a rotational period of 1.8 days for the star. We s uspect that the observed modes are trapped modes separated by 3 or 4 u ndetected normal modes. Average period spacings of 16.70s or 16.16s ar e consistent with the data. However, a luminosity estimate and an irre futable period spacing are necessary to determine PG 0122+200's mass.