FURTHER OBSERVATIONS OF THE PLANETARY-NEBULA IN THE GLOBULAR-CLUSTER M22

The proper motion of the central star of the newly-discovered planetary nebula in the globular cluster M22 strongly confirms cluster membership, in agreement with radial-velocity data from the discovery group. An accurate optical position of the central star differs by a few arcseconds from the IR source position derived by the discoverers. Photographic photometry of the star on plates spanning nearly a century shows that the star has probably brightened by ∼0.2 mag since 1900, but there is no evidence of variations on shorter timescales. Use of the larger mean cluster reddening and smaller distance found from recent studies has less effect on the central star temperature and luminosity than do other uncertainties. Dust within the nebula is probably responsible for the excess reddening of the background red companion to the central star.