The compact radio nucleus of the Seyfert galaxy NGC 1068

Abstract

We present a 5-GHz MERLIN map of the central arcsecond of the Seyfert 2 galaxy NGC 1068. We detect the four-component structure reported in earlier observations. The higher angular resolution and sensitivity of the MERLIN measurements show extended emission consistent with a flaring jet which appears to originate from the vicinity of a 100-mas compact double source. One of the components in the 100-mas double has an inverted spectral index, and hence we identify this as a ‘radio core’ at the active nucleus of the galaxy. We have evaluated previous positions, and by use of improved calibrator positions determine the J2000 position of the inverted spectrum core/nucleus to be at RA= 02^h42^m40^s7098, Dec. = − 00°00′47″!938, with an error of ± 20 mas in each coordinate. We compare the MERLIN image with post-COSTAR HST [O iii] and continuum images, and discuss the radio and optical positions for the active nucleus. However, it appears unlikely that much progress can be made until significant improvements are made in the astrometric precision of the HST images.