We present the preliminary results of a survey of the open clusters NGC3532 and NGC2287 for new white dwarf members which can help improve understanding of the form of the upper end of the stellar initial mass-final mass relation .
We identify four objects with cooling times , distances and proper motions consistent with membership of these clusters .
We find that despite a range in age of \sim 100Myrs the masses of the four heaviest white dwarfs in NGC3532 span the narrow mass interval M _ { WD } \approx 0.9 - 1.0M _ { \odot } suggesting that the initial mass-final mass relation is relatively flatter over 4.5M _ { \odot } \mathrel { \hbox { \raise 2.15 pt \hbox { $ < $ } \hbox to 0.0 pt { \lower 2.15 pt \hbox { $ \sim$% } } } } M _ { init } \mathrel { \hbox { \raise 2.15 pt \hbox { $ < $ } \hbox to 0.0 pt { \lower 2.15 pt \hbox { $ \sim$% } } } } 6.5M _ { \odot } than at immediately lower masses .
Additionally , we have unearthed WD J0646-203 which is possibly the most massive cluster white dwarf identified to date .
With M _ { WD } \approx 1.1M _ { \odot } it seems likely to be composed of ONe and has a cooling time consistent with it having evolved from a single star .