PHR 1315-6555 is a rare case of a Galactic Planetary Nebula that is a proven member of the Open Cluster AL 1 .
This allows its distance to be defined with precision and thus the accurate measurement of its physical characteristics along with the parameters of its Central Star ( CS ) .
In this work we use HST to detect this unique CS and constrain the cluster ’ s physical parameters .
Our results suggest that the cluster rests at a distance of \sim 12 kpc , is highly reddened , and has an age of around 0.66 Gyrs and a turn-off mass of \sim 2.2 M _ { \odot } .
Our deep Colour Magnitude Diagram ( CMD ) suggests that the metallicity of the cluster is subsolar ( Z=0.006 ) .
Our photometric measurements indicate that the PN ’ s core is a faint blue star close to the nebular apparent centre , with an observed dereddened visual VEGA magnitude of 21.82 \pm 0.60 .
A significant contribution from any possible binary companion is unlikely but possible .
Our results show that the CS has an effective Zanstra temperature of around 113 kK and a mass of 0.58 M _ { \odot } providing a unique additional point to the fundamental White Dwarf Initial-to-Final-Mass Relation .