2005ApJ...628L.139M

We present the first integral field spectroscopy observations of the two planetary nebulae NGC 3242 and NGC 4361 with the VIMOS instrument attached to VLT-UT3. By co-adding a large number of spaxels, we reach an emission-line detection limit of 5x10^–18 ergs/cm2/s/arcsec2. In the case of NGC 3242, we succeed in determining some properties of the halo. The radial surface brightness profile in [O III] implies increasing mass loss before the formation of the planetary nebula. Traces of the mysterious ``rings'' are clearly visible. We find for the first time an apparent temperature gradient across a halo: from about 16,000 K close to the shell/halo transition to 20,000 K at the halo's outer edge. No line emission is seen in the suspected halo region of NGC 4361 down to the sensitivity limit.