Only one certain classical nova eruption has ever been detected inside a
globular cluster - nova 1860 A.D. (T Sco) in M80. During a survey of M87 we
have detected an erupting star coincident (to within 0.08 pixels) with a
globular cluster of that giant elliptical galaxy. We are able to discount
variables in the foreground or background of M87. The light curve and color of
the erupting star match those expected for a nova at the distance of M87. The
chance superposition of an M87 field nova on the globular cluster is very
unlikely but cannot be completely ruled out.Our detection hints at a globular
cluster nova frequency f∼.004 novae/cluster/year, much higher than
previous observations have suggested
