Bi-Site Observations of the ZZ Ceti PG2303+243

PG2303+243 is a pulsating DA white dwarf (or ZZ Ceti), located on the cool side of the instability strip. Due to the potential interest of that star for asteroseismologic analysis, we reobserved PG2303+243. The improved time resolution (4 µHz) of this new set of data allows the detection of as many as 22 periods. A preliminary analysis, using the most recently available studies of linear adiabatic non radial pulsations in stratified white dwarfs, is presented. We suggest that 18 of the 22 modes observed, may be identified as g-modes of 1 = 1, 2, 3 and 4, trapped, or partially-trapped in the outer hydrogen envelope. From the data presented in this paper we derive a preliminary value — 8.7 ≤ logQ H ≤— 7.6 for the hydrogen envelope mass.