  We present a detailed study of a bipolar, possible Type I planetary nebula
(PN), PHR1315-6555 (PN G305.3-03.1), that was discovered as part of the
Macquarie/AAO/Strasbourg H-alpha planetary nebula project (MASH) and that we
considered at the time was an excellent candidate for membership of the
distant, compact, intermediate-age open cluster, ESO 96-SC04. The strong
evidence for this association is presented here making this the only known
example of a PN physically associated with a Galactic open cluster. Cluster
membership is extremely important as it allows for very precise estimates of
the fundamental properties of the PN as the cluster is at a known distance. The
PN was discovered by one of us (QAP) during systematic MASH searches for new
Galactic PNe of the AAO/UKST H-alpha survey and had been missed in earlier
broadband surveys, including specific CCD studies of the host cluster. We
present original discovery images and CTIO 4m MOSAIC-II camera follow-up
narrow-band images that reveal its bipolar morphology. We also present: (i)
low-resolution optical spectra that spectroscopically confirm the PN; (ii)
accurate radial velocities of the PN and cluster stars from high resolution
spectroscopy which show they are consistent; and (iii) a reliable, independent
distance estimate to the PN using a robust PN distance indicator which agrees
with the published cluster distance to within the errors. We also provide
preliminary estimates of basic PN properties and abundance estimates from
deeper spectra that show it to be of possible Type I chemistry. This is also
consistent its estimated turn-off mass. Taken together these findings present a
powerful case for clear physical association between the PN and host cluster.
Results for this association will be of considerable interest to specialists
across differing astrophysical disciplines, including PNe, white dwarfs, and
open clusters.
